Fuses are important for any battery system, regardless of age or type. Here's why: Wiring is the weak point: Even older batteries can deliver enough current to overheat wiring if there's a short circuit or overload. The fuse protects the wiring, not the battery itself. It's crucial to have fuses on all cables connected to your lithium-ion battery. These fuses primarily protect the wiring, not the appliances themselves. If a fault occurs and the cable starts to overheat, the fuse will blow, preventing a potential fire. While lithium-ion batteries have built-in safety mechanisms (a Battery Management System or BMS), it's unwise to rely solely on these. A BMS can fail, and fuses provide an additional layer of protection. Remember to choose a fuse with an appropriate rating for the cable it's protecting. This ensures the fuse will blow before the cable overheats.
Thank you for pointing this out . A BMS IS NOT FOOLPROOF and they do fail . The whole thing about this video is added saftey and a lot don’t get it cos they think the bms Is 100% safe
@ Not all battery management systems are made equal I've just got the eco warrior 12v 280ah battery But the shutdown amperage is about 800 amps which is insane I would imagine it were overheat and shut down anyway before it reached 800 amps But I'm not willing to put that to the test. lol
@@UrbanVanlife yes mate I agree. Safer is better. I think some people took it as fogstar are selling something that is dangerous. This is incorrect, It is not and these batteries are safe to drop in. Adding the t fuse makes it safer. This is not a bad thing.
Hi both. Excellent advice. When I changed to lithium on my motorhome, I installed the T type fuse. Surprising how many people aren't aware of the problems that could arise. Very well explained 👍
Ashamed to say I was such an A##hole making unnecessary childish remarks. I was wrong and apologise. You are good people, giving a huge gift to other vanlifers. I ordered a class T holder and Fuse, I have only 300 ah but that is enough, it is my first build. Waited three years saving up and now finally I change from dreaming to doing. Thank you very much for this critical information, best regards!
Oh my friend I’m also guilty of doing it as well so not a problem at all . We don’t take much to heart here budddy . But appreciate your comment and good luck with the build hope to see you on the road sir
I think it's great that you are trying to inform people of safer ways to protect yourself and your installation, but the HRC fuse you fitted will not stop thermal runaway if the battery has a fault and catches fire. LIFEP04 lithiun are the safest of the lithium batteries as they are less suseptable to thermal runaway if you have a fault . I am in Australia and use a brand called Enerdrive which has an internal BMS and built in short circuit protection etc ect. We also have electrical standards about battery location and where they are installed in a habitable location. P.S I am an Electrician and work with DC power supplies and very large battery Banks.
Thanks for mentioning T-fuses. As of respect to the high amperage my safety aproach is 3 way: 1) BMS - which should detect overcurrent. But if Mosfets burn thru 2) high amp DC-Breaker switch which should break by magnetic overcurrent detection, and if this fails 3) Class-T fuse or similar that consists of 20kAmps breaking capabilities for last row of defence.
most people that are sold these lithium batteries are told nothing and are sold to them as a replacement to lead acid batteries with devastating consequences, replacing lead acid with lithium means adding a lot more than a fuse to their current charging setup...lead acid or calcium batteries will tolerate an over charge, but lithium will not.
The 20K amps breaking capability is the stand out feature of the T-Class fuse - absolutely no argument from me. It should contain any high amperage arcing. Out of my experience with a group of more than 2.5K van builders (and DIYs!) I have not heard of ONE instance, where a van blew up or even caught fire caused by a short circuit situation on a LiFePO4 battery. It is just not a common occurance. Yes, I can distrust the BMS. Yes, I can distrust my DC breaker. And add a T-Class fuse. But that's like distrusting your brakes, your seat belt and then buying a helmet. I'd be more afraid of poor crimps, miscalculated cable sizes, fusing and improper connections.
them mosfets and capacitors have a high fail rate, i fix electronic devices often, they short and on a battery they can be devastating, shorts are the last thing you want on a lithium battery.
I've watched so many videos over the years regarding van electricity, and most videos are similar and sometimes inaccurate. This video was refreshing and depressing at the same time; refreshing that I still can learn something valuable and depressing that it took so many hours of viewing other videos to find it. What's the lesson here? No matter how repetitive, keep watching these videos because everybody knows a little something worthwhile that may not have been expressed before. Cables, switches, fuses, etc... may seem mundane when compared to charge controllers, inverters, and batteries, but their selection makes for a healthy, happy system when done with purpose. Who'da thunk.
most camper and caravan chargers are not made for lithium-ion batteries, when charging from car, most cars these days have 150amp+ alternators and at least 32amps of that will go to the caravan battery, if lead acid it may boil a little but a lithium cannot tolerate overcharging.
@KarenSmith-ef9kk the chargers designed for lithium shut off when charged as do the batteries so they can’t be over charged . Don’t fit lead acid it’s not the 80a
@@KarenSmith-ef9kk lithium batteries have BMS built in to them short circuit and thermal protection controlling charging rate Fuses are to prevent wiring overload . If your blowing a 200A fuse (24kw) you have a serious short circuit
@@UrbanVanlife electronics fail a lot, these days, just because we are in 2025 doesn't make old tech obsolete, cars had fuel injection and turbo's and self adjusting tappets back in 1959, well before electronics/computers were needed and they were reliable and cheap to repair, these days, you got sensors that fail and finding a real fault on a car is trial and error, unless you are a real mechanic and not a technician that uses a computer to try and find faults which could be multiple as the code could be skewed, if a sensor malfunctions....so get the idea that tech is better, out of your head, tech is there complicate things and make it more expensive and harder to repair, ie when it breaks buy another.....making everything you buy disposable.
every bit of power for a lithium battery needs to go through a different charger to make it safe, most caravans and motor-homes charge from vehicle or from mains supply on site, ie from control panel in both instances, even then the battery could be charging at between 4 and 8ah depending on what the size of battery it was designed to charge, the alternator could be sending as little as 16 to 32 amps per hour depending on relays...not hard see it could be devastating, with so little information about new technologies, companies will sell, because even they haven't got a clue what they are selling to the customer, the fuse that was talked about on here is nothing more than a band aid and will not stop an overcharge. ( welcome to the world of physics in layman’s terms ).
Dramatic ? Yes, overly? No. You’re absolutely correct in what you have done to raise a very important issue. You may only get one chance to buy right !
Hi thanks for the kind comments - I’m sorry it’s an expensive upgrade. So the next thing to blow your minds … inverters … they are now being used to supply very high current items such as hobs …. Because you can with modern batteries. Victron supply inverters that work with ‘trip’ switches similar to what’s in your house and will sense a short circuit and cut off the power so your electric shock you receive shouldn’t kill you. Other (I believe vast majority) of inverters can’t be used with trip switches. So think grandmas house in the 1970’s type circuit protection. Not ideal in a van that’s been home made and perhaps some reassurance is placed on a fuse saving you. So annoyingly you need to research ‘centre tapped inverters’ and why they are different from non centre tapped. You can still add trip switches …. RCBs and others but it’s complicated and I don’t think anyone is doing it. You can find some info on RUclips about it but it’s not ‘advertised’ or explained by the inverter manufacturers at all from what I have experienced. Sorry to be annoying again.
Just my 2p worth: Lithium as in LIpo4 batteries are actually very safe compared to alternative lithium batteries. Usually when shorted / abused they will get hot and vent but wont go on fire as such... I believe they do get hot enough to set wood on fire so worth keeping in mind when planning. The larger fuse you are using in this video is no doubt a better fuse to a mega fuse. The arcing should really be an issue as its not high voltage so is not enough to jump across gaps. Not saying the fuse upgrade is not a good thing but I think people watching that might not have the money for the type of fuse and will now worry about it IMO its all bit scaremongering how it was represented. Something not mentioned that really should have been is the BMS in the battery. This is actually what stops your battery from going "boom" . The BMS will go into short and over current protection in no time not to mention potential to sacrifice itself if something really messed up happened. Anyways no hate I like your videos I just thought it was worth noting for other to see yes this is a good upgrade but thats all it is an upgrade... You should always fuse ANY live feed IMO and if it all goes wrong you have the BMS.
But all I’d say is no bms I’d flawless and they can fail . And for the cost it’s added saftey that could save your whole van And we appreciate your comment and thank you . We think it’s allwsys best to fuse your battery and fuse it with the correct fuse as well
Kudos Neil for raising this with such honesty, despite having 7 years experience (with formal training) in marine electrics, I followed this guy for placing mega, ANL and class T in my lifepo4 system… ‘EXPLORIST life Mobile Marine & Off-Grid Electrical’. He has a great video called ‘DIFFERENT TYPES OF DC FUSES (for a DIY Camper Electrical system)’. As well as explaining the ratings & reasoning for all to understand, he sheds some light on why class T was not used / heard of much in the last 5 years.
I'm glad this video prompted me to do some research, but it does need to be said that a Class T fuse isn't going to be the right solution for every install. I have a 300Ah 12v system and a MBRF terminal fuse (£11) plus a fuse holder (£24) is more than adequate. The fuse needs to be rated to lower amps than the cable from my battery is. Cheaper MBRFs are available, those prices are what I've found for Blue Sea Systems which are not the cheapest, but they're a well respected high end brand. At that sort of price I can even afford to carry a spare fuse! You may well want a Class T for your inverter and you're requirements might not match mine depending on a number of factors... The key takeaway is that it's really worth getting some advice that's relevant to your install and not to be put off by the 'high' price of Class T. £35 to protect my system really is extremely affordable.
I truly didn't know this but have the other fuse options you showed. Think I'll upgrade before my install is complete. Massively appreciate it. If I ever see you guys out and about, I owe you an irn bru
Hi Neil, that really surprises me that you guys were not aware of these fuses. They are mentioned on some of the Facebook groups. Before I knew of these I had bought MRBF fuses for the batteries. Mine are not fitted as yet. I'm still considering changing to the T rated, infact your video Might have convinced me to do so. Anyway I have 2 300A MRBF fuses and holders to sell you😊 What was your fuses rated at.
Yep not a single person has a class t fitted or the other kind that Darren Tony fitted that we mentioned in the video . And don’t worry it shocked me as well
The MRBF fuses should be fine. One 300A MRBF fuse will allow you to safely draw up to 3600W @ 12vdc, 7200W @ 24vdc, or 14400W at 48vdc if you have the battery capacity to handle such loads. If you use both fuses from seperate battery setups, you can double those figures. Hope this helps.
Having been in close proximity to large industrial fuses when they go bang, I would not be mounting the fuse so close to the battery as to possibly cause damage to the battery when it goes bang. At least put it in a thermal battery box or put some asbestos sheet between the fuse and the plastic wall of the battery housing. 💥 👍
Loving your vids and your journey s. Plus your little dogs. Just be safe out there. Keep it Real, to all van people and everyone living on the road or streets. Be safe stay safe.
Darn proper advice from a Sparky here, in our modern worlds, we have breakers in our homes and businesses which can trip and you can reset. They are just really a modern convenience, fuses on the other hand and that depends which hand you’re looking at ha ha, fuses always blow in my 50 years of being an electrician and a large building and facility maintenance engineer. I’ve never not seen a fuse, not fail and do its job at protecting you. And it’s important to learn there are a wide variety in flavor of fuses, it’s just not a simple element that will go poof when you need it sometimes they can hold their pooping for a little bit because that’s a necessary part of the circuit so yeah excellent information proper installation large wiring always with this kind of stuff 👍👏👏👏
Nice video and should make some DIY installers think about installing a fuse perhaps. I think there are two issues with why people do not install fuses. 1) They do not understand how to work out what size fuse they need. 2) They think they do not need one because another part of the system already has a fuse and they can save money / don't need it (battery isolators, inverters, batteries bms and busbars have limits / fuses). My view is I would prefer to replace a fuse than replace an inverter or a battery as they are cheaper. My own rule is go with the highest thickness cable you can and the fuse installed should be lower than everything else in the system to protect them. I always use 2awg or 35mm cables for my battery and inverter setup which can handle 210 amps. Always remember 12v systems pull more amps the higher the watts you pull compared to a 24v system. When I build out systems if your total watts is going to exceed 1000 watts then its time to look at a 24v system to be safe.
Correct me if I am wrong but higher volts = greater risk to humans. And that's why high-voltage systems require certified people to work on them, and why generally speaking something "small" like 12v systems are considered much more safe and popular in DIY communities. In fact, I would like to go with a 1v system as long as I could afford them thick copper cables lol. I am just baffled a little bit why you say "[rather than 12v] look at a 24v system to be safe". Like no no no, properly and adequately size the fuses and cables to whatever amps you have running, but all other things equal, LOWER voltage is better "to be safe". Or am I wrong?
Great tip. Have you had to remove all the other fuses?. I think all the companies that sell the lithium batteries should've said something about the fuses when you bought the battery... But still a good shout on you're part. Let's hope other vanlifers have done the same as your good selves😊
More than happy to rely on my built in BMS after consultation with the professional Battery and vehicle electrical company that retro fitted it for me.
Not that professional if there not fitting a t class fuse or a mrbf fuse to your System mate . Also the BMS is a computer . Question Do you own a computer Has it ever crashed or failed ?? That’s what I’d ask Cos if it dose that’s all your van wireing going up in flames . Also I’m guessing if them cables are in your van then that’s gone as well
@KevSmith-v4u Can you please argue your case with factual statements? So far all you have contributed with is a baseless opinion, which is wasting people's time.
All UK mains plug tops Fuses 3-13 amp (BS1362) Are of this type with sand inside to quench the arc from inductive loads so current will not flow via the arc after it blows!
that will not stop the battery catching fire/exploding, the arc has nothing to do with thermal runaway, can be from overcharge, too high of charge rate or cell failure causing short circuits within the battery, all will result in same out come. search for ev and e-bike fires in china the results are frightening.
Every so often I come across a real gem of a RUclips post. This one stopped me in my tracks and really made me think. I have LiFePO4 batteries with what I hope are good BMS units designed to prevent this type of rapid extreme discharge. But hope isn’t enough. I ordered the T Class fuses, it made no sense to me not to add this protection. Thanks for your post, I wish you both well.
The problem is to ensure it’s all safe the necessary calculations must be applied. It is possible that the delay in the fuse allows your cable to melt, switch to melt and a fire.
I’ve got a mega fuse set up on my leisure batteries and I’ve only got 140 amp/h setup. Especially important when you’ve got massive cables feeding a 3kw inverter. Well done for highlighting the safety issue :)
I'm ¾ way into my van build. I had no idea about this . Thankyou so much for the info. I will definitely be fitting the the fuse to my battery . Cheers guys brilliant vlog 👍
Canadian, here. I've come to expect the un-earned confidence from my neighbours below. It's refreshing to watch someone 'own' their issues (thanks, Brits!). Comments ought to be helpful in this building context. 100% correct concerning an appropriate fuse. Cheap ones will simply weld together causing all manner of chaos. Quality doesn't cost - it pays. Keep having fun!
This is why i always tell people to get electrical systems fitted by a qualified engineer. i recently had a camper in that had inverter and tripping issues, after doing an initial check over , the install wasn't bad but needed improvement. The big problem arose when doing an insulation resistance test, it failed . the cable looked new and the owner showed me receipts, but turns out the cable was cheap fake of a branded cable. While i understand budget constraints etc, you spend all the cash on fancy inverters, charge controllers and batteries, yet miss the thing that ultimately keeps you safe . Good video and it will help the DIY'ers to keep a little bit safer
You have made a very good and interesting point Granted a class t fuse is far superior to a mega fuse and as you correctly stated you can get ark flash within the fuse this is why a mega fuse is rated to a maximum of 48 volts If you have a 12 v system there isn’t enough voltage potential to cause ark flash so on the lower voltage systems a mega is fine personally anything over 24 v system I use type t Thankyou again for an very informative video
One can not be superior to another if they have different areas of application. An apple is not in an absolute sense superior to a peanut. One may feed a human and one may feed a mouse. Or maybe you load up your petrol car with rocket fuel because rocket fuel is "superior"?
MRBFs (the alternative that you showed), are cheaper and fine for 12v & 24v systems using Lithium chemistry batteries. Once you get to 48v and above I fully agree with using a Class T fuse and holder. Both are rated for marine use, so their use in a van is fine - subject to the voltage limits noted above. Spares for both are available at most chandlers (marine things shop), but carrying a spare fuse is always a good idea. Hopefully you have something better than just gaffer/duct tape covering the positive battery terminal 8:55, since anything metal shorting this out is before the fuse. I’d also cover the red cable with some corrugated cable sheathing to prevent physical damage - a few quid on Fleabay delivered, and you can get a split version so you don’t have to remove anything to fit it.
@alanhat5252 If that's a problem, you already need a larger gauge of wire - especially low voltage DC. Mechanical damage leading to a short will be a LOT hotter!
Excellent, iv been banging on about these fuses for some time. Everyone thought i did not know what i was on about .but it doesn't protect your battery, but it will stop your wires from melting.
Emma here not Neil. We have always had fuses on our system, however we did not have the correct type of fuse for the lithium battery, which shocked us as when we first got our very first lithium battery installed by professionals I will add and they checked our electrical system, they did not advise us on this type of fuse or inform us of them, so it’s more about awareness than anything as other people we spoke to also did not have the correct fuses.
Great video, just ordered the same parts as you, I went down the mega fuse route as I’d never heard of these ! Cheers you could have saved my life and van 😅
Thanks for sharing, I got MRBF fuse for mine in addition as all helps make sure if something goes wrong doesn’t it. I remember your video on the circuit breakers, always good of you to share, as you buy things which are rated on paper correctly, in practice if they aren’t made to cope with the job in hand, you get a problem don’t you. Hope you’re both good and didn’t get too many problems from the storm. All the best, David 🙌
That's some good info. It's a shame that the battery suppliers aren't pushing this! I know it isn't their problem, but as you've stated, not many are using suitable fuses
You dont need High Voltage Rated fuses on Low voltage 12v circuits as arching the gap cannot occur at this voltage , standard 200A fuses as used with 12v lead acid batteries are sufficent . Its there to prevent cable and wiring current faults not the battery. ( + Circuit breakers ) The BMS , inside well designed ! lithium batteries has short circuit and thermal runaway prevention built in
I agree on this, but also mounted on the positive terminal a mbrf fuse. It cost not much and can help you if the others fail. Take a mbrf fuse for the correct voltage, I use 24 volt on my system, so my fuses are for max 48 volt.
@CanarianCamperBuild By all means , its just that lithium batteries get a bad press , due mostly to electric bikes and scooters fires ,(mostly chinease) these do not have the level of BMS safety features ,and use rudamentry chargers. The fuse /circuit breakers are there to prevent overheating of the wiring causing a fire situation no matter what the power source ...
@@johnwalker5366 ok then, I'm not 1 to jump on the band wagon, I research everything and for at least 5 years before committing to anything, (better safe than sorry), to see the long term results....if not give us your findings 5 years from now?.....I'll be keen to see your conclusions.
@@KarenSmith-ef9kk I do understand your concerns But the fact remains fuses/circuit breakers are there to stop overloading the wiring and cables causing fires ,not to protect the Battery. My concern with is that Industral HV fuses rated at 415v a/c designed to withstand arc rupturing are not required at 12v DC no arching can take place at this low voltage. They are not fast type blow either as there designed to carry there rated current at 415v a/c for at least 6seconds per there manufactured spec. ie not designed or tested for 12v or DC use! Are the cables in RVs able to withstand this 6sec overcurrent ? If your concerned battery BMS is unreliable or unsafe , then just use leisure lead acid AGM batteries, ie reliable , predictable tech and a 1/4 of the cost to purchase . Seems in China there going back to Acid AGM batteries ,on scooters etc ,becuase cheap lithium batteries have cuased so many fires !
I spoke with fogstar when fitting my 300ah and yes, they did recommend a T class fuse. I described my installation and that I planned on using an MRBF fuse and they advised that this is also sufficient.
Well highlighted issue ! First came across advice on MRBF fuses on the group I belong to, SBMCC, and subsequently fitted them. I find technical info on responsible and informed sites to be very useful if, as I am, you are inexperienced or technically unsure. Why wouldn’t you spend a few extra quid to protect £000s invested in your van / boat. Thank you, from them who didn’t know😅
I have watched this vlog now twice and I get what your saying Neil and glad your on top of it now but surly fogstar should of known this and should of put you right on this matter. If not that's pretty bad as a company as your now living full time what if it did go up while asleep in your van you could be no more my mate. Not digging at the company at all or you guys what so ever but surely they would know this yea ?? All the best and glad your on it now mate love the vlogs and you guys
This isn’t a fault of fogstar at all, and they do recommend the correct fuses to customers, our issue was we already had lithium in the van prior to getting the fogstar so we didn’t ask if we needed anything else as we had had it put in by someone else and assumed our system was correct going off what we had previously been advised, so it’s a user error on our part in that sense.
Very interesting...I was just thinking about these the other day, and wondering if I should be getting one...I already have terminal fuses installed...so am not sure if I did to triple up (megafuse, terminal fuse, and T-class)
To be pedantic, I would also add that it is safer to have the shutoff switch on the negative terminal. Electricity actually flows from negative to positive, not from positive to negative as most wiring diagrams show. This continues from a convention when real electrical flow was not understood as well, in the past. The long and short is that there is always a greater potential for an arc to occur when breaking the positive lead to the terminal, compared to the negative terminal, due to the greater energy potential from negative to positive real flow. This is also why you are advised in manuals to disconnect the negative terminal first, when disconnecting or replacing your starter battery, and reconnecting positive first, then negative, when installing a new battery. You can do it either way, but you probably notice the chance of a large spark is greater if you connect negative then positive on your new starter battery. Obviously, the much lower impedance of a lithium battery increases this risk, if there are any weak components in the wiring system. It's a small risk, but that's why the advice is negative-positive to disconnect, positive-negative to connect a battery. The cutoff switch is effectively the same thing, except most people follow the convention of cutoff to positive terminal. It makes earthing isolation easier, but strictly it increases the risk of sparking or arcing.
Consider + to be positive for electron flow -> so you are testing for electrons. Disconnecting the negative first in vehicles is because any exposed metal areas of the vehicle is 'Negative', and it is easier to contact the positive to negative (vehicle chassis for example) with metal tools and causing high discharge and heat, if negative isn't on the battery terminal then the electrons cannot flow through the battery. There is nothing wrong with what you have said these are just foot notes :)
That is not true. You should put the fuse on the terminal(+ or -) that is Not connected to the chassis. So Positive is almost always the correct pole to installa the fuse.
@@sudosu4133 No it's not. Research it, and the reasons why this is the case. It'll come up even on a simple Google search. Don't play with electricity, if you're not sure. -ve off switch is the standard but +ve has become a convention for non-professionals, as it's easier to discount energised nodes from downstream grounding. The only thing you need to be careful of on a self build electrical system is your negative side grounding into a fuse box, junction, or connected devices like B2Bs or Solar controllers, so that you don't leave branches of the system energised. As you normally install separate breakers and fuses around these elements, it should not be an issue, but going around each node with a multimeter after install will confirm you are not energised.
fair play for the install of the fuse i feel the supplyer or manafactue need to educate thair coustomers on safe practices for lithium batteries people realydont understand. the amount of energy these attabatteries contain great video very Well explained safe and happy adventures all the best gav keep up the good videos
I think it’s more end user to be honest mate . There are plenty of dangers and we have to take our selves accountable . I mean you can buy a Stanley blade in B&M but no one tells you to be careful with it . And we all have cuts to prove that lol
Mate hands up we didn’t know any thing about it as well . So hence a humble we made a mistake and didn’t know and here’s what we found out video was needed . And new pants after doing the research
I don't think he did any lol. The whole narrative that "regular" fuses are confined to an operating interval, which is totally unspecified (?), and then there's these other special "higher grade" fuses that somehow doesn't have the same limitation (i.e. follows the same physical laws), smells like a scam to me. If it really is true that fuses only work as expected from X amps to Y amps then this interval should be well specified, and my logical processor tells me that should be equally true for all fuses. Maybe the RUclipsr will take these things more seriously in the future when he posts videos and instead of asking us to just "believe him", present some real facts and rationale. Oh the irony that he began this video bashing down on an unsubstantiated comment and then he does the very same thing except in the form of a video lol.
@@themartinanderssonHis knowledge is laughable but I'm sure it's nothing to do with the money. He'll be doing a review next on the new mind-blowing solar generator 🙃
@ According to other comments, arcing can't even happen on 12v systems. So sad that you can't trust what you see on RUclips these days. They are all crooked and corrupt.
I got to give it a thumbs up on this one. Well done guys for bringing such an important safety characteristic, associated with large lithium battery banks, specially paralleled batteries. The mega fuse is good for max 2kA fault current. A lithium bank can exceed 5-6kA fault current. Class T is a very wise and safe route, also there is OutBack DC breakers that are rated at 10kA fault current interruption, and cost about £60.
As another commenter has pointed out, the interrupt rating of some fuses may depend on voltage. The linked class T fuses are rated to 20kA across the whole voltage range (125V or 160V, depending on the make), but the MRBF fuses' interrupt rating varies between 10kA at 14V and only 2kA at 58V. Unfortunately, battery manufacturers such as Fogstar do not specify the maximum fault current in their datasheets. This information should be provided by a reliable manufacturer so that the appropriate protection may be correctly selected.
Great info guys ,another point to note ,I wonder if everyone has bonded there AC consumer units earth to the chassis correctly to a separate earth point than the negatives earth on the DC side they Must be on separate points on the chassis even though they both go to earth ,take care 👍🚐👍🚐
@@UrbanVanlifeI think what he's saying is that the clips in the early part of the video show a different type of chemistry to what your fogstar uses. Lifepo4 is very stable. You are right about the fuse situation though. I have mega fuses, proper DC breakers and then the BMS cut off rated to my application. I doubt at 12v there would be sufficient energy to arc across a mega fuse but 48v would be abit more of a worry.
@@Marks-GarageAn arc welder will work quite well with 12v. Using the specified very low internal resistance for the cells used in these batteries, a simple calculation shows that several thousand amps could flow into a short circuit.
This has got me thinking about all the portable power stations that have flooded the market over the last couple of years and what their technologies and protection are like. Most now seem to be the LiPo technology but are they fused internally like this?
Not lipo (lithium polymer), lifepo4 (lithium iron phosphate). Lipo's are used for things like drones and RC models where you need massive current from a tiny battery. They like to go on fire. Lifepo4 or lfp are used for energy storage and electric vehicles as they are cheap and stable. They can still fail and vent flammable toxic gas which is why they should probably be contained and vented to outside any living/sleeping areas. They don't generally spontaneously go on fire though.
What I find mildly confusing is that either people are ignoring the safety advice given by the companies that sell the batteries and associated hardware or the companies are also not aware. As an electrician I have always panicked a little, sometimes prompting comment, at certain installs, where smaller sized cables are used, possibly because some may assume that if something is 12V you only need small sized cables. Whereas in reality you would need a bigger sized cables for a lower voltage serving equipment of a particular load (wattage), because the load remains the same if it was run from 240v or 12v, therefore if the voltage drops then the ampage increases. Cables have a definitive current carrying capacity irrespective of voltage and you could end up overloading your cables, which in turn heat up and worse case scenario catch fire. I was also concerned about safety in vans because they are not fixed like a building, so looking at what the marine industry has in place is such a no brainer, as they say a little knowledge can be dangerous so always get advice from a specialist or do a course of some description. When ever I get to the point of building a van I will definitely get advise on protection and safety of electrical systems and oversize all my cables too. Well done for putting this out there and well done for the person who gave you the advise, maybe the first comment could have been a bit more useful had it come with some information, If it is not constructive, criticism should be limited.
nobody from Fogstar mentioned the thing Neil has. Basically they want to sell you the batteries but they just cant be bothered giving you sound safety advice to fit it. Theres a whole spec sheet on Fogstar's site that accompanies each battery and literally NOWHERE on those spec sheet has anything covered by Neil's video. I find that very bad. Fogstar and other lithium battery firms need to pull their fingers out and give proper safety advice.
Blimey 😳 sorry for not reading the comments but I have read up on the fuses they do blow quicker than the normal mega fuses you obviously know more than me so big respect but I also respect Neil's knowledge and experience for thinking of others ❤️.
Hi guys, surely the battery manufacturer should provide this information to the buyer regarding safe and proper installation. Did you ask Fogstar regarding these fuses? All the best guys
They do if you ask all the correct questions, however we had lithium in the van prior to getting our fogstar batteries and thought we had the right systems in place so didn’t ask if we needed anything else as we had been running off lithium for a few years. Someone who has bought from fogstar has all answers your question in the comments and they where given the correct advice and information
Having this type of fuse is a good idea, will have a look at my 270ah lithium setup in my van. You do seem to be talking about lithium ion which is far more volatile than lithium LifePO4 which will not explode like you said. But I'm sure you are using LifePO4 lithium batteries. I do agree, be as safe as you can. But I do get a little tied, OMG, you have lithium batteries in your caravan, aren't you scared they will blow up, no. Even had this talking to the builders of our new 12M marine rescue boat. We had in our specs, 300ah of lithium house batteries, they put in AGM, oh we are still on the fence with the safety of lithium. I just about hit the roof, lithium are just as safe or even safer than AGM when using quality batteries, quality hardware and installed by qualified people. Quality lithium batteries have a BMS and I'm sure you know what this is and this is first line of defense with any major faults with your battery system. Sorry for the long rant, but I do agree, a class T fuse is a good idea, but where do you stop.
Emma here. We agree LifePO4 are safer and the BMS is the first line of safety but for us we just want to be as safe as possible, we didn’t know about these fuses for lithium as many others didn’t who we spoke to, but again that is down to user error (ie us not doing enough research when we had them first put in the van) to which we held our hand up, but also have learnt that BMS’s can also fail, so for us it’s about having another added protection. Many people fit things into their vans and do not know enough to be doing it so we wanted to raise some awareness for people to look into things.
Haha , Niel I'm in the process of as a beginner setting up and installing all my victron setup in my camper conversion. I have thankfully done the correct research and have purchased one of these a 350amp T class with 400amp fuse holder( it's a beast). Thought I was going overboard as as you said people were going its not a space ship . I told them that just as you said when using lithium a short could weld up and jump or arc on a mega fuse as a tremendous amount of amps more than the system could handle would happen if there was a short. The sand will suppress and prevent that. £100 for that in my mind is worth the the time and investment in your tin house. So Niel I must be in the weirdo area for fitting one ages ago 😂😂
Not all Lithium is made the same. LiFePO4 Prismatic Cells are very safe the don't just explode or set on fire like lithium-ion cells that scare the crap out of me every time I have to replace them. Plus the BMS if set properly just cuts off power anytime something happens out of spec, that being said I can't argue with having a proper fused system so I'll probably get one of these too.
Some commenters have mentioned that Fogstar has recommended additional fusing - If the manufacturer doesn't trust their own BMS, why should anyone else? Also, if we ignore the BMS (Which would apply to any chemistry if we could trust it) - The chemistry doesn't really make it any safer. Here's a scenario: 1) You short out your LiFePO4 battery, the high fault current (6kA?) exceeds the interrupt rating of your fuse and welds it closed. 2) The battery heats and the fault current reduces, let's say 4-600A. The chemistry is "safe" so the battery itself doesn't combust. 3) You now have a continuous 4-600A flowing through your main battery cables, your failed fuse, your isolator and whatever else up until the short. We're talking about 240mm² to 500mm² cable needed to survive this without becoming a heater. (Sizes may vary depending on where you look, but it's big) You're still going to end up with a major fire risk either way, just at different speeds.
A lot of people build their own vans & that’s why more campsites are saying no self build vans. Not everyone has your expertise in building your own van. Love your channel.
Iv never known any one being refused on a camp site to be honest . And I hope I never come across a site that dose that cos I’ll be telling them strait
Lol. Thata so funny and a drama. 1. They use victron... Victron use mega fuses. 2. There lithium-ion batteries.. There not, theyre lithium fe-ion.. no blow up... 3. Could have got a ketto which is much less. 4. A battery Has a bms with current protection. 5 a full short will, blow a fuse and trip the bms. The bms will likely go back on, but the fuse will break the circuit. It wont come back on with a short and welded fuse. Now if you habe a lithium battery ... And you get a battery short (fairly common) you get a fire ball, but as they are internal no fuse is going to help you. 😢 If you do by chance, wire, fuse/breaker, correctly, then your unlikely to have any issues... Now this can be fairly rare from what ive seen 😊
@UrbanVanlife bms can and they do, but usually its a lower level of fault rendering the thing useless. The new code is that batteries have breakers on them or in them. I did mention cable fuses. But people can often put them in the wrong place... Far from the battery. Fuses work and what you described with arching is higher voltage. There is a table online
@campervancodgers124 VIDEO FOR CHEAPER FUSE ALTERNATIVE ruclips.net/video/tTtGNUk07ro/видео.html 12VOLT PLANET LINKS FUSE HOLDER - www.12voltplanet.co.uk/blue-sea-systems-5007100-class-t-fuse-block-110-200a.html T CLASS FUSE - www.12voltplanet.co.uk/class-t-fuses.html
I was nearly gutted when you showed the class T as they had gone completely under my radar on van build and on my boat rewire. Then you dropped in the quick pic of the terminal cube fuses which I fitted on all my pos terminals. So now I don't feel quite so bad, although being belts an braces I may well fit a class t on the main feed off the battery bank. Really glad you put this video out thanks
Not just what you have written.. A proper voltage drop calculation for each cable run.. Cable ventilation and no bundling etc.. Not just size but type of cable.. not AluCu and use copper lugs with copper cable particularly on heavy stuff. The Boat Safety Standards might be an interesting read.. eg... no soldering is a big one.. cables crossing fuel and gas ... also hot and cold.. and wear and sharp things. Question is (which I'm going to put in a main comment) What and why that size of fuse 😻 ... too big? Why only one etc. Yep a little can be dangerous.. Why is their fuse, switch and battery exposed to impact? Switch could be accessed from inside.. safer. A full design is key.
the fogstar battery you have and 99% of current lithium batterys are in fact lifep04.. which is a completly different chemistry to old style lithium batterys which are quite volatile if treated wrongly ..lithium ion phosphate or lifepo4 for short batterys are far far safer they don't burst into flames when damaged like the old style lithium batterys ..the battery in your phone and laptop is more of a danger that the fogstar lifep04 battery..
Well explained Neil, did not know the massive current outage from a battery when at fault. This should protect the equipment in the van, some comments were saying they rely on the BMS built into the battery, well if that things melting then it will not help. Its important to realise that if the battery goes into meltdown, this fuse only protects the 12V circuits. Suggest some sort of heat or smoke detector near the battery in the garage. Another thing i do not understand is normally the output from solar panels is not fused at the solar panel, ask Daz as a short in the cable caused him nearly to lose his van. Why are they not fused?.
Solar wiring (I suspect) isn't fused on the outdoor part because it's extra connections to rot & potentially cause fires. There should be a fuse (or reliable circuit breaker) in the circuit somewhere though!
@@alanhat5252it would appear not, Daz aka urban motorhome made a video after nearly burning his van down, drilled a hole, caught the wiring. And the voltage from the solar panels shorted out.
You need to work out what current your system draws, (wattage)then divide by the volts ie your battery 12v, then go a bit higher, I had a friend work mine out but believe 12 volt planet would help if you buy from them x
@ I have the correct size normal fuse on my system, but I’m hearing that you kneed some kind of huge fuse, which would not protect the cables, just stop the welding of the fuse holder, I’m conFUSED, to pardon the pun 😁
@@michaelwilliams3861 I didn't use the massive same fuse a Neil ours was a Mrbf, basically as I have much less stuff but, it made sense to me as from the battery to the fuse there was no protection if the fuse failed. I just went with my guy no harm In a extra safety which is why I'm attending a workshop in Hull on van electric safety on Saturday if your interested let me know and I'll give you the details I do know there is still places.
It depends on the spec of the BMS in the battery, if you want to draw 3000W for a 3kwh inverter, you would need a 250A-300A fuse to run that load and the batteries BMS would have to be able to supply that 250A of current or more to run it without dropping the BMS out on overcurrent protection. IE: 12v x 250A = 3000W. If for instance your batteries BMS can only discharge at a maximum of 200A for say 20-30 seconds or more, it could still run a 3000W inverter with a microwave up to 2400W, ie 12v x 200A = 2400W. Hope this helps.
once again an informative vlog. , something i have noticed and wondered when seeing people upgrading to larger batteries is how many upgrade their kill switches to as they also have a maximum current load
It's hard to tell from the video but it looks like your disconnect switch is just a switch and not a fuse or breaker so yeah not having a fusing in line would be pretty bad.
I just came across this video. Well explained. I recently upgraded to two 460AH Roamer batteries . By shere luck. I went with the MRBF fuses, rated to the max draw if my circuit. I will look at the T-Class fuse, If I can find room. Thank you.
This is very well known in the boating world, is unfortunate that this has not got to the van world, the use of MRBF fuse is good for 12v, this was confirmed by Eaton who manufactures many industrial fuses. Much easier to install and actually protect cable from battery terminals. Also easier to get than T fuses. Bluesea also make buss bars for these like make installation simpler
Hi I put a comment on Sam’s video when he fitted his Fogstar about these fuses and he said he’d look into it hopefully he did as he comes across as a guy who same as a lot of us does it right to the best of our knowledge at the time. I have two 280Ah fogstars in parallel so capable of delivering a lot more current (500A) than through one BMS so luckily bumped into the right guy when I was installing mine. Thanks for highlighting it and saving someone’s van and possibly lives.
The latest here in Australia is the lipo batteries on new builds have to be housed in a metal sealed compartment with gas venting to the exterior , if the the RV is able to connect to mains power . Toxic smoke is a concern with a battery fault fire . The linked supplier have run out of stock , interesting .
For us it’s another layer of protection, and the correct fuse that should be used, there are other less expensive types which are just as safe but we couldn’t fit that in our set up due to space constraints but more safety in our opinion is never a bad thing!
I'm going to be that smug git now and tell you i did it right first time... I use high breaking capacity fuses from the forklift industry. They operate under the same principle as the t class fuses you show, ie, they are filled with sand. The ones I have are rated for 10000 amps at 96v and I am using them at "48v nominal" which for me works out to be around 54v give or take... In theory the BMS inside the battery should give you an amount of protection, but the fuse is a last resort in case the MOSFETs fail. I wish battery manufacturers had the forethought to include fuse protection to their BMS systems, but there we go...
Hi. So are u saying that you’ve NEVER used fuses on your batteries system in the past OR you have but not the correct type and relied on the BMS? I have inline fuses on my lithium LiFePO4 set up, just not the one you mention, as I have never heard or had it recommended in the past. Thanks
Hi we have always had fuses on our system, we where unaware that we needed to have the additional fuse for the lithium battery installed as we had previously had our lithium battery prior to the fogstar ones installed by professionals and these fuses where not mentioned when they fitted and installed it.
If you use lifepo4 batteries with a built in BMS, in the event of a short circuit the BMS will reach its maximum output and shut down, so a mega fuse should be ample as the fuse would faail and the BMS shut off the power. There arent many people fitting the expensive fast blow fuses.
If your happy with the built in bms that you can’t see and don’t know if it will or will not break the flow then that’s ok . Personally for the money we have spent on our van a little extra level of saftey for under £100 then I’ll take it . Guess it’s each to their own . And there arnt many people fitting these fuses that’s correct . But there are also people still fitting Amazon breakers and not mega fuses . I just know when it comes to saftey I’ll feel a lot happier with more than less
Remember the class t has two used, 1) protect from an overload of the rated amps - so in this vid its rated at 200amp. 2) Protect from a short somewhere after the class t as if this happens the battery will dump its entire contents in a split second, this fuse will not only blow because it goes over is rating but then stop an arc happening which could very well in a bms unless its been potted (Victron?). Not only does it protect you if faffing on the electrical system and you're waving leads around, but what about in an accident who knows whats going to get damaged etc. Its food for thought, so like UV I designed my system with one in place and its connected about 10cm from the battery positive before then connecting to the bms etc.
As an idiot who has accidently ( clumsily ) shorted out his 12 volt LifePo4 , it never caused an Arc but instead blew the spanner apart in one big bang before I knew what was happening , so my mega fuse "spanner" saved my battery going boom 🤣
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Fuses are important for any battery system, regardless of age or type. Here's why:
Wiring is the weak point: Even older batteries can deliver enough current to overheat wiring if there's a short circuit or overload. The fuse protects the wiring, not the battery itself. It's crucial to have fuses on all cables connected to your lithium-ion battery.
These fuses primarily protect the wiring, not the appliances themselves. If a fault occurs and the cable starts to overheat, the fuse will blow, preventing a potential fire.
While lithium-ion batteries have built-in safety mechanisms (a Battery Management System or BMS), it's unwise to rely solely on these. A BMS can fail, and fuses provide an additional layer of protection.
Remember to choose a fuse with an appropriate rating for the cable it's protecting. This ensures the fuse will blow before the cable overheats.
Thank you for pointing this out . A BMS IS NOT FOOLPROOF and they do fail . The whole thing about this video is added saftey and a lot don’t get it cos they think the bms Is 100% safe
Iv also pinned this comment
@ Not all battery management systems are made equal I've just got the eco warrior 12v 280ah battery But the shutdown amperage is about 800 amps which is insane I would imagine it were overheat and shut down anyway before it reached 800 amps But I'm not willing to put that to the test. lol
@@UrbanVanlife yes mate I agree. Safer is better.
I think some people took it as fogstar are selling something that is dangerous. This is incorrect, It is not and these batteries are safe to drop in.
Adding the t fuse makes it safer. This is not a bad thing.
Hi both. Excellent advice. When I changed to lithium on my motorhome, I installed the T type fuse. Surprising how many people aren't aware of the problems that could arise. Very well explained 👍
We were not aware of it and many others we spoke to weren’t either so if it helps people be safer it’s good to put it out there!
Ashamed to say I was such an A##hole making unnecessary childish remarks. I was wrong and apologise. You are good people, giving a huge gift to other vanlifers. I ordered a class T holder and Fuse, I have only 300 ah but that is enough, it is my first build. Waited three years saving up and now finally I change from dreaming to doing. Thank you very much for this critical information, best regards!
Oh my friend I’m also guilty of doing it as well so not a problem at all . We don’t take much to heart here budddy . But appreciate your comment and good luck with the build hope to see you on the road sir
I think it's great that you are trying to inform people of safer ways to protect yourself and your installation, but the HRC fuse you fitted will not stop thermal runaway if the battery has a fault and catches fire. LIFEP04 lithiun are the safest of the lithium batteries as they are less suseptable to thermal runaway if you have a fault . I am in Australia and use a brand called Enerdrive which has an internal BMS and built in short circuit protection etc ect. We also have electrical standards about battery location and where they are installed in a habitable location. P.S I am an Electrician and work with DC power supplies and very large battery Banks.
The "built in short circuit protection" works how? Sounds like a battery with this protection is 100% safe or no?
Spot on.
Thanks for mentioning T-fuses.
As of respect to the high amperage my safety aproach is 3 way:
1) BMS - which should detect overcurrent. But if Mosfets burn thru
2) high amp DC-Breaker switch which should break by magnetic overcurrent detection, and if this fails
3) Class-T fuse or similar that consists of 20kAmps breaking capabilities for last row of defence.
most people that are sold these lithium batteries are told nothing and are sold to them as a replacement to lead acid batteries with devastating consequences, replacing lead acid with lithium means adding a lot more than a fuse to their current charging setup...lead acid or calcium batteries will tolerate an over charge, but lithium will not.
The 20K amps breaking capability is the stand out feature of the T-Class fuse - absolutely no argument from me. It should contain any high amperage arcing.
Out of my experience with a group of more than 2.5K van builders (and DIYs!) I have not heard of ONE instance, where a van blew up or even caught fire caused by a short circuit situation on a LiFePO4 battery. It is just not a common occurance.
Yes, I can distrust the BMS. Yes, I can distrust my DC breaker. And add a T-Class fuse.
But that's like distrusting your brakes, your seat belt and then buying a helmet.
I'd be more afraid of poor crimps, miscalculated cable sizes, fusing and improper connections.
them mosfets and capacitors have a high fail rate, i fix electronic devices often, they short and on a battery they can be devastating, shorts are the last thing you want on a lithium battery.
What size is your battery cable? Thanks 🙏
I've watched so many videos over the years regarding van electricity, and most videos are similar and sometimes inaccurate. This video was refreshing and depressing at the same time; refreshing that I still can learn something valuable and depressing that it took so many hours of viewing other videos to find it.
What's the lesson here? No matter how repetitive, keep watching these videos because everybody knows a little something worthwhile that may not have been expressed before. Cables, switches, fuses, etc... may seem mundane when compared to charge controllers, inverters, and batteries, but their selection makes for a healthy, happy system when done with purpose. Who'da thunk.
most camper and caravan chargers are not made for lithium-ion batteries, when charging from car, most cars these days have 150amp+ alternators and at least 32amps of that will go to the caravan battery, if lead acid it may boil a little but a lithium cannot tolerate overcharging.
@KarenSmith-ef9kk the chargers designed for lithium shut off when charged as do the batteries so they can’t be over charged . Don’t fit lead acid it’s not the 80a
@@KarenSmith-ef9kk lithium batteries have BMS built in to them short circuit and thermal protection controlling charging rate Fuses are to prevent wiring overload . If your blowing a 200A fuse (24kw) you have a serious short circuit
@@UrbanVanlife electronics fail a lot, these days, just because we are in 2025 doesn't make old tech obsolete, cars had fuel injection and turbo's and self adjusting tappets back in 1959, well before electronics/computers were needed and they were reliable and cheap to repair, these days, you got sensors that fail and finding a real fault on a car is trial and error, unless you are a real mechanic and not a technician that uses a computer to try and find faults which could be multiple as the code could be skewed, if a sensor malfunctions....so get the idea that tech is better, out of your head, tech is there complicate things and make it more expensive and harder to repair, ie when it breaks buy another.....making everything you buy disposable.
@@johnwalker5366That would be 2.4kw not 24kw, ie 12v x 200A = 2400W. Cheers
Thanks guys keeping us all safe 🙏 love you guys
You guys are so right that you can not skimp especially on safety. Thanks for sharing awesome vid...Ray
every bit of power for a lithium battery needs to go through a different charger to make it safe, most caravans and motor-homes charge from vehicle or from mains supply on site, ie from control panel in both instances, even then the battery could be charging at between 4 and 8ah depending on what the size of battery it was designed to charge, the alternator could be sending as little as 16 to 32 amps per hour depending on relays...not hard see it could be devastating, with so little information about new technologies, companies will sell, because even they haven't got a clue what they are selling to the customer, the fuse that was talked about on here is nothing more than a band aid and will not stop an overcharge. ( welcome to the world of physics in layman’s terms ).
Dramatic ? Yes, overly? No. You’re absolutely correct in what you have done to raise a very important issue. You may only get one chance to buy right !
Hi thanks for the kind comments - I’m sorry it’s an expensive upgrade. So the next thing to blow your minds … inverters … they are now being used to supply very high current items such as hobs …. Because you can with modern batteries. Victron supply inverters that work with ‘trip’ switches similar to what’s in your house and will sense a short circuit and cut off the power so your electric shock you receive shouldn’t kill you. Other (I believe vast majority) of inverters can’t be used with trip switches. So think grandmas house in the 1970’s type circuit protection. Not ideal in a van that’s been home made and perhaps some reassurance is placed on a fuse saving you. So annoyingly you need to research ‘centre tapped inverters’ and why they are different from non centre tapped. You can still add trip switches …. RCBs and others but it’s complicated and I don’t think anyone is doing it. You can find some info on RUclips about it but it’s not ‘advertised’ or explained by the inverter manufacturers at all from what I have experienced. Sorry to be annoying again.
Just my 2p worth:
Lithium as in LIpo4 batteries are actually very safe compared to alternative lithium batteries. Usually when shorted / abused they will get hot and vent but wont go on fire as such... I believe they do get hot enough to set wood on fire so worth keeping in mind when planning.
The larger fuse you are using in this video is no doubt a better fuse to a mega fuse. The arcing should really be an issue as its not high voltage so is not enough to jump across gaps. Not saying the fuse upgrade is not a good thing but I think people watching that might not have the money for the type of fuse and will now worry about it IMO its all bit scaremongering how it was represented.
Something not mentioned that really should have been is the BMS in the battery. This is actually what stops your battery from going "boom" . The BMS will go into short and over current protection in no time not to mention potential to sacrifice itself if something really messed up happened.
Anyways no hate I like your videos I just thought it was worth noting for other to see yes this is a good upgrade but thats all it is an upgrade... You should always fuse ANY live feed IMO and if it all goes wrong you have the BMS.
But all I’d say is no bms I’d flawless and they can fail .
And for the cost it’s added saftey that could save your whole van
And we appreciate your comment and thank you . We think it’s allwsys best to fuse your battery and fuse it with the correct fuse as well
Kudos Neil for raising this with such honesty, despite having 7 years experience (with formal training) in marine electrics, I followed this guy for placing mega, ANL and class T in my lifepo4 system… ‘EXPLORIST life Mobile Marine & Off-Grid Electrical’. He has a great video called ‘DIFFERENT TYPES OF DC FUSES (for a DIY Camper Electrical system)’. As well as explaining the ratings & reasoning for all to understand, he sheds some light on why class T was not used / heard of much in the last 5 years.
Thanks mate I’ll check him out . So many ppl rely on the bms . At the end of ther day there a computer and can fail
A mbrf terminal fuse at the right voltage rating does the job much cheaper!
I'm glad this video prompted me to do some research, but it does need to be said that a Class T fuse isn't going to be the right solution for every install. I have a 300Ah 12v system and a MBRF terminal fuse (£11) plus a fuse holder (£24) is more than adequate. The fuse needs to be rated to lower amps than the cable from my battery is.
Cheaper MBRFs are available, those prices are what I've found for Blue Sea Systems which are not the cheapest, but they're a well respected high end brand. At that sort of price I can even afford to carry a spare fuse!
You may well want a Class T for your inverter and you're requirements might not match mine depending on a number of factors...
The key takeaway is that it's really worth getting some advice that's relevant to your install and not to be put off by the 'high' price of Class T.
£35 to protect my system really is extremely affordable.
Wow didn't know that how many vans are running about as a fire Risk thanks for sharing and helping others
I truly didn't know this but have the other fuse options you showed. Think I'll upgrade before my install is complete.
Massively appreciate it.
If I ever see you guys out and about, I owe you an irn bru
I believe ALOT of people,including myself had No idea!!!Thanks for the wonderfully informative video!!
We didn’t know about it . But I’m glad we do
Respect for passing on the information as soon as you got it . Without people like yourselves a lot of people could have lost their vehicles.
Hi Neil, that really surprises me that you guys were not aware of these fuses. They are mentioned on some of the Facebook groups. Before I knew of these I had bought MRBF fuses for the batteries. Mine are not fitted as yet. I'm still considering changing to the T rated, infact your video Might have convinced me to do so. Anyway I have 2 300A MRBF fuses and holders to sell you😊
What was your fuses rated at.
Yep not a single person has a class t fitted or the other kind that Darren Tony fitted that we mentioned in the video . And don’t worry it shocked me as well
The MRBF fuses should be fine.
One 300A MRBF fuse will allow you to safely draw up to 3600W @ 12vdc, 7200W @ 24vdc, or 14400W at 48vdc if you have the battery capacity to handle such loads.
If you use both fuses from seperate battery setups, you can double those figures.
Hope this helps.
Makes Sense ,as You said not Seen other Builders use a Similar thing .
A Incident Waiting to Happen
Good Vid Son
Ohhh but I think your going to see a few more videos about these fuses from people who can explain it a little bit better than me
One of the best recommendations you have done, at best all batteries should be fused, Regards
Thank you sir
Great information Neil 👍I don't have lithium but its well worth knowing👍
This was a new one to us mate as it seems to be to a lot of people . But obviously all the smart ases seemed to know about it tho
Having been in close proximity to large industrial fuses when they go bang, I would not be mounting the fuse so close to the battery as to possibly cause damage to the battery when it goes bang. At least put it in a thermal battery box or put some asbestos sheet between the fuse and the plastic wall of the battery housing. 💥 👍
We ok with this one mate there in no risk of a bang with these fuses
Loving your vids and your journey s. Plus your little dogs. Just be safe out there. Keep it Real, to all van people and everyone living on the road or streets. Be safe stay safe.
Thank you! Will do hope you are well!!!
Darn proper advice from a Sparky here, in our modern worlds, we have breakers in our homes and businesses which can trip and you can reset. They are just really a modern convenience, fuses on the other hand and that depends which hand you’re looking at ha ha, fuses always blow in my 50 years of being an electrician and a large building and facility maintenance engineer. I’ve never not seen a fuse, not fail and do its job at protecting you.
And it’s important to learn there are a wide variety in flavor of fuses, it’s just not a simple element that will go poof when you need it sometimes they can hold their pooping for a little bit because that’s a necessary part of the circuit so yeah excellent information proper installation large wiring always with this kind of stuff 👍👏👏👏
"I've never not seen a fuse, not fail". My head hurts. Can you please rephrase?
Nice video and should make some DIY installers think about installing a fuse perhaps. I think there are two issues with why people do not install fuses. 1) They do not understand how to work out what size fuse they need. 2) They think they do not need one because another part of the system already has a fuse and they can save money / don't need it (battery isolators, inverters, batteries bms and busbars have limits / fuses). My view is I would prefer to replace a fuse than replace an inverter or a battery as they are cheaper. My own rule is go with the highest thickness cable you can and the fuse installed should be lower than everything else in the system to protect them. I always use 2awg or 35mm cables for my battery and inverter setup which can handle 210 amps. Always remember 12v systems pull more amps the higher the watts you pull compared to a 24v system. When I build out systems if your total watts is going to exceed 1000 watts then its time to look at a 24v system to be safe.
Correct me if I am wrong but higher volts = greater risk to humans. And that's why high-voltage systems require certified people to work on them, and why generally speaking something "small" like 12v systems are considered much more safe and popular in DIY communities. In fact, I would like to go with a 1v system as long as I could afford them thick copper cables lol.
I am just baffled a little bit why you say "[rather than 12v] look at a 24v system to be safe". Like no no no, properly and adequately size the fuses and cables to whatever amps you have running, but all other things equal, LOWER voltage is better "to be safe". Or am I wrong?
@themartinandersson not wrong but the amps and the power in this battery could kill you
Great tip. Have you had to remove all the other fuses?. I think all the companies that sell the lithium batteries should've said something about the fuses when you bought the battery... But still a good shout on you're part. Let's hope other vanlifers have done the same as your good selves😊
No we where just advised to have it before the feed goes in to the vans main system
@UrbanVanlife Thanks for the update.... top peeps
More than happy to rely on my built in BMS after consultation with the professional Battery and vehicle electrical company that retro fitted it for me.
Not that professional if there not fitting a t class fuse or a mrbf fuse to your System mate . Also the BMS is a computer .
Question
Do you own a computer
Has it ever crashed or failed ??
That’s what I’d ask
Cos if it dose that’s all your van wireing going up in flames . Also I’m guessing if them cables are in your van then that’s gone as well
@@UrbanVanlife As I said I'm happy to rely on my BMS
@KevSmith-v4u Can you please argue your case with factual statements? So far all you have contributed with is a baseless opinion, which is wasting people's time.
retro fitted is classed as best we can do ( bodge) where I come from.
@@themartinandersson I'm satisfied with my BMS protection, that's not a baseless opinion......it's a fact
All UK mains plug tops Fuses 3-13 amp (BS1362) Are of this type with sand inside to quench the arc from inductive loads so current will not flow via the arc after it blows!
that will not stop the battery catching fire/exploding, the arc has nothing to do with thermal runaway, can be from overcharge, too high of charge rate or cell failure causing short circuits within the battery, all will result in same out come. search for ev and e-bike fires in china the results are frightening.
Every so often I come across a real gem of a RUclips post. This one stopped me in my tracks and really made me think. I have LiFePO4 batteries with what I hope are good BMS units designed to prevent this type of rapid extreme discharge. But hope isn’t enough. I ordered the T Class fuses, it made no sense to me not to add this protection. Thanks for your post, I wish you both well.
Well when we found out it worried us as we didn’t realise, and when we spoke to many other people they also didn’t know, hence the video.
The problem is to ensure it’s all safe the necessary calculations must be applied. It is possible that the delay in the fuse allows your cable to melt, switch to melt and a fire.
Thank you for sharing this. I will definitely be adding this to my system. Thanks again, safe travels. All the best. 👍🚐🐾🐾😎
I’ve got a mega fuse set up on my leisure batteries and I’ve only got 140 amp/h setup. Especially important when you’ve got massive cables feeding a 3kw inverter. Well done for highlighting the safety issue :)
I'm ¾ way into my van build. I had no idea about this . Thankyou so much for the info. I will definitely be fitting the the fuse to my battery . Cheers guys brilliant vlog 👍
Canadian, here. I've come to expect the un-earned confidence from my neighbours below. It's refreshing to watch someone 'own' their issues (thanks, Brits!). Comments ought to be helpful in this building context. 100% correct concerning an appropriate fuse. Cheap ones will simply weld together causing all manner of chaos. Quality doesn't cost - it pays. Keep having fun!
Thank you, we didn’t know so we held our hands up, every day is a school day!!
This is why i always tell people to get electrical systems fitted by a qualified engineer. i recently had a camper in that had inverter and tripping issues, after doing an initial check over , the install wasn't bad but needed improvement. The big problem arose when doing an insulation resistance test, it failed . the cable looked new and the owner showed me receipts, but turns out the cable was cheap fake of a branded cable. While i understand budget constraints etc, you spend all the cash on fancy inverters, charge controllers and batteries, yet miss the thing that ultimately keeps you safe . Good video and it will help the DIY'ers to keep a little bit safer
You have made a very good and interesting point
Granted a class t fuse is far superior to a mega fuse and as you correctly stated you can get ark flash within the fuse this is why a mega fuse is rated to a maximum of 48 volts
If you have a 12 v system there isn’t enough voltage potential to cause ark flash so on the lower voltage systems a mega is fine personally anything over 24 v system I use type t
Thankyou again for an very informative video
One can not be superior to another if they have different areas of application. An apple is not in an absolute sense superior to a peanut. One may feed a human and one may feed a mouse. Or maybe you load up your petrol car with rocket fuel because rocket fuel is "superior"?
MRBFs (the alternative that you showed), are cheaper and fine for 12v & 24v systems using Lithium chemistry batteries. Once you get to 48v and above I fully agree with using a Class T fuse and holder. Both are rated for marine use, so their use in a van is fine - subject to the voltage limits noted above.
Spares for both are available at most chandlers (marine things shop), but carrying a spare fuse is always a good idea.
Hopefully you have something better than just gaffer/duct tape covering the positive battery terminal 8:55, since anything metal shorting this out is before the fuse. I’d also cover the red cable with some corrugated cable sheathing to prevent physical damage - a few quid on Fleabay delivered, and you can get a split version so you don’t have to remove anything to fit it.
I'm not convinced about sheathing as it will thermally insulate the cable, possibly leading to a different set of problems.
@alanhat5252 If that's a problem, you already need a larger gauge of wire - especially low voltage DC. Mechanical damage leading to a short will be a LOT hotter!
Excellent, iv been banging on about these fuses for some time. Everyone thought i did not know what i was on about .but it doesn't protect your battery, but it will stop your wires from melting.
@@zummerzetwoodsman1067 bms will stop your wires melting faster than the fuse
any normal fuse will stop your wire from melting. was he saying he didnt have any fuse in his cicuit or did he replace a #20 fuse for a #60 fuse?
@danny323dee especially when it arcs(aic) over and continues to deliver many thousands of amps
You just figured out why you need fuses on your DC side but you are giving advice on how to do installs?
Emma here not Neil. We have always had fuses on our system, however we did not have the correct type of fuse for the lithium battery, which shocked us as when we first got our very first lithium battery installed by professionals I will add and they checked our electrical system, they did not advise us on this type of fuse or inform us of them, so it’s more about awareness than anything as other people we spoke to also did not have the correct fuses.
Great video, just ordered the same parts as you, I went down the mega fuse route as I’d never heard of these ! Cheers you could have saved my life and van 😅
A extremely worth whole video giving out very great worth while information Thank you.
Thanks for sharing, I got MRBF fuse for mine in addition as all helps make sure if something goes wrong doesn’t it. I remember your video on the circuit breakers, always good of you to share, as you buy things which are rated on paper correctly, in practice if they aren’t made to cope with the job in hand, you get a problem don’t you. Hope you’re both good and didn’t get too many problems from the storm. All the best, David 🙌
That's some good info. It's a shame that the battery suppliers aren't pushing this! I know it isn't their problem, but as you've stated, not many are using suitable fuses
You dont need High Voltage Rated fuses on Low voltage 12v circuits as arching the gap cannot occur at this voltage , standard 200A fuses as used with 12v lead acid batteries are sufficent . Its there to prevent cable and wiring current faults not the battery. ( + Circuit breakers )
The BMS , inside well designed ! lithium batteries has short circuit and thermal runaway prevention built in
I agree on this, but also mounted on the positive terminal a mbrf fuse. It cost not much and can help you if the others fail. Take a mbrf fuse for the correct voltage, I use 24 volt on my system, so my fuses are for max 48 volt.
@CanarianCamperBuild By all means , its just that lithium batteries get a bad press , due mostly to electric bikes and scooters fires ,(mostly chinease) these do not have the level of BMS safety features ,and use rudamentry chargers. The fuse /circuit breakers are there to prevent overheating of the wiring causing a fire situation no matter what the power source ...
@@johnwalker5366 ok then, I'm not 1 to jump on the band wagon, I research everything and for at least 5 years before committing to anything, (better safe than sorry), to see the long term results....if not give us your findings 5 years from now?.....I'll be keen to see your conclusions.
@johnwalker5366 yep
@@KarenSmith-ef9kk I do understand your concerns But the fact remains fuses/circuit breakers are there to stop overloading the wiring and cables causing fires ,not to protect the Battery.
My concern with is that Industral HV fuses rated at 415v a/c designed to withstand arc rupturing are not required at 12v DC no arching can take place at this low voltage.
They are not fast type blow either as there designed to carry there rated current at 415v a/c for at least 6seconds per there manufactured spec. ie not designed or tested for 12v or DC use!
Are the cables in RVs able to withstand this 6sec overcurrent ?
If your concerned battery BMS is unreliable or unsafe , then just use leisure lead acid AGM batteries, ie reliable , predictable tech and a 1/4 of the cost to purchase . Seems in China there going back to Acid AGM batteries ,on scooters etc ,becuase cheap lithium batteries have cuased so many fires !
I spoke with fogstar when fitting my 300ah and yes, they did recommend a T class fuse. I described my installation and that I planned on using an MRBF fuse and they advised that this is also sufficient.
Yer they do recomend it . And both systems are great thank you for pointing this out
What size class t fuse did you use for your 300ah set up😊
Well highlighted issue ! First came across advice on MRBF fuses on the group I belong to, SBMCC, and subsequently fitted them. I find technical info on responsible and informed sites to be very useful if, as I am, you are inexperienced or technically unsure. Why wouldn’t you spend a few extra quid to protect £000s invested in your van / boat. Thank you, from them who didn’t know😅
I have watched this vlog now twice and I get what your saying Neil and glad your on top of it now but surly fogstar should of known this and should of put you right on this matter. If not that's pretty bad as a company as your now living full time what if it did go up while asleep in your van you could be no more my mate. Not digging at the company at all or you guys what so ever but surely they would know this yea ?? All the best and glad your on it now mate love the vlogs and you guys
This isn’t a fault of fogstar at all, and they do recommend the correct fuses to customers, our issue was we already had lithium in the van prior to getting the fogstar so we didn’t ask if we needed anything else as we had had it put in by someone else and assumed our system was correct going off what we had previously been advised, so it’s a user error on our part in that sense.
Very interesting...I was just thinking about these the other day, and wondering if I should be getting one...I already have terminal fuses installed...so am not sure if I did to triple up (megafuse, terminal fuse, and T-class)
To be pedantic, I would also add that it is safer to have the shutoff switch on the negative terminal. Electricity actually flows from negative to positive, not from positive to negative as most wiring diagrams show. This continues from a convention when real electrical flow was not understood as well, in the past.
The long and short is that there is always a greater potential for an arc to occur when breaking the positive lead to the terminal, compared to the negative terminal, due to the greater energy potential from negative to positive real flow.
This is also why you are advised in manuals to disconnect the negative terminal first, when disconnecting or replacing your starter battery, and reconnecting positive first, then negative, when installing a new battery. You can do it either way, but you probably notice the chance of a large spark is greater if you connect negative then positive on your new starter battery.
Obviously, the much lower impedance of a lithium battery increases this risk, if there are any weak components in the wiring system. It's a small risk, but that's why the advice is negative-positive to disconnect, positive-negative to connect a battery. The cutoff switch is effectively the same thing, except most people follow the convention of cutoff to positive terminal. It makes earthing isolation easier, but strictly it increases the risk of sparking or arcing.
Right well looks like we are buying a second breaker . Thanks for the advice
Consider + to be positive for electron flow -> so you are testing for electrons. Disconnecting the negative first in vehicles is because any exposed metal areas of the vehicle is 'Negative', and it is easier to contact the positive to negative (vehicle chassis for example) with metal tools and causing high discharge and heat, if negative isn't on the battery terminal then the electrons cannot flow through the battery. There is nothing wrong with what you have said these are just foot notes :)
That is not true. You should put the fuse on the terminal(+ or -) that is Not connected to the chassis. So Positive is almost always the correct pole to installa the fuse.
@@sudosu4133 No it's not. Research it, and the reasons why this is the case. It'll come up even on a simple Google search. Don't play with electricity, if you're not sure. -ve off switch is the standard but +ve has become a convention for non-professionals, as it's easier to discount energised nodes from downstream grounding.
The only thing you need to be careful of on a self build electrical system is your negative side grounding into a fuse box, junction, or connected devices like B2Bs or Solar controllers, so that you don't leave branches of the system energised. As you normally install separate breakers and fuses around these elements, it should not be an issue, but going around each node with a multimeter after install will confirm you are not energised.
@@UrbanVanlife And you need do a video 📹 too so we all can be kept updated 😊 Thank you ❤️
fair play for the install of the fuse i feel the supplyer or manafactue need to educate thair coustomers on safe practices for lithium batteries people realydont understand. the amount of energy these attabatteries contain great video very Well explained safe and happy adventures all the best gav keep up the good videos
I think it’s more end user to be honest mate . There are plenty of dangers and we have to take our selves accountable . I mean you can buy a Stanley blade in B&M but no one tells you to be careful with it . And we all have cuts to prove that lol
@ verry true
Or even document it within there fitting instructions would possibly be a solution.
Well done to Boatman ! for high lighting .....in first place...always somebody about with better way of explaining things ...Doh !
Massive shout out thank you I didn't know about this ordered one just now😊
Mate hands up we didn’t know any thing about it as well . So hence a humble we made a mistake and didn’t know and here’s what we found out video was needed . And new pants after doing the research
Many thanks.
Can you post links to the reseach you done?
I don't think he did any lol. The whole narrative that "regular" fuses are confined to an operating interval, which is totally unspecified (?), and then there's these other special "higher grade" fuses that somehow doesn't have the same limitation (i.e. follows the same physical laws), smells like a scam to me.
If it really is true that fuses only work as expected from X amps to Y amps then this interval should be well specified, and my logical processor tells me that should be equally true for all fuses.
Maybe the RUclipsr will take these things more seriously in the future when he posts videos and instead of asking us to just "believe him", present some real facts and rationale.
Oh the irony that he began this video bashing down on an unsubstantiated comment and then he does the very same thing except in the form of a video lol.
@@themartinanderssonHis knowledge is laughable but I'm sure it's nothing to do with the money. He'll be doing a review next on the new mind-blowing solar generator 🙃
@ According to other comments, arcing can't even happen on 12v systems. So sad that you can't trust what you see on RUclips these days. They are all crooked and corrupt.
Hi thanks for the video my battery is 280amp fogstar do you know the size of fuze thanks
Your best speaking to 12v planet bud and seeing what they advise for your system . We got told 200amp
I got to give it a thumbs up on this one. Well done guys for bringing such an important safety characteristic, associated with large lithium battery banks, specially paralleled batteries. The mega fuse is good for max 2kA fault current. A lithium bank can exceed 5-6kA fault current. Class T is a very wise and safe route, also there is OutBack DC breakers that are rated at 10kA fault current interruption, and cost about £60.
As another commenter has pointed out, the interrupt rating of some fuses may depend on voltage. The linked class T fuses are rated to 20kA across the whole voltage range (125V or 160V, depending on the make), but the MRBF fuses' interrupt rating varies between 10kA at 14V and only 2kA at 58V. Unfortunately, battery manufacturers such as Fogstar do not specify the maximum fault current in their datasheets. This information should be provided by a reliable manufacturer so that the appropriate protection may be correctly selected.
Great info guys ,another point to note ,I wonder if everyone has bonded there AC consumer units earth to the chassis correctly to a separate earth point than the negatives earth on the DC side they Must be on separate points on the chassis even though they both go to earth ,take care 👍🚐👍🚐
I think we have to stop using word lithium and use the lithium chemistry names instead e.g., li-on, lifepo4, etc. because the differences are massive
may be just take the advice in this video and know ur safe reguardless of what ou want to call things
@@UrbanVanlifeI think what he's saying is that the clips in the early part of the video show a different type of chemistry to what your fogstar uses. Lifepo4 is very stable. You are right about the fuse situation though. I have mega fuses, proper DC breakers and then the BMS cut off rated to my application. I doubt at 12v there would be sufficient energy to arc across a mega fuse but 48v would be abit more of a worry.
@@Marks-Garage
It doesn't matter what the voltage is...
@@Marks-GarageAn arc welder will work quite well with 12v. Using the specified very low internal resistance for the cells used in these batteries, a simple calculation shows that several thousand amps could flow into a short circuit.
@@UrbanVanlife😂 well no. Calling 2 different things the same thing isn’t how it works is it. I wouldn’t take your advice unless I wanted to die
This has got me thinking about all the portable power stations that have flooded the market over the last couple of years and what their technologies and protection are like. Most now seem to be the LiPo technology but are they fused internally like this?
Not lipo (lithium polymer), lifepo4 (lithium iron phosphate). Lipo's are used for things like drones and RC models where you need massive current from a tiny battery. They like to go on fire. Lifepo4 or lfp are used for energy storage and electric vehicles as they are cheap and stable. They can still fail and vent flammable toxic gas which is why they should probably be contained and vented to outside any living/sleeping areas. They don't generally spontaneously go on fire though.
What I find mildly confusing is that either people are ignoring the safety advice given by the companies that sell the batteries and associated hardware or the companies are also not aware.
As an electrician I have always panicked a little, sometimes prompting comment, at certain installs, where smaller sized cables are used, possibly because some may assume that if something is 12V you only need small sized cables. Whereas in reality you would need a bigger sized cables for a lower voltage serving equipment of a particular load (wattage), because the load remains the same if it was run from 240v or 12v, therefore if the voltage drops then the ampage increases. Cables have a definitive current carrying capacity irrespective of voltage and you could end up overloading your cables, which in turn heat up and worse case scenario catch fire.
I was also concerned about safety in vans because they are not fixed like a building, so looking at what the marine industry has in place is such a no brainer, as they say a little knowledge can be dangerous so always get advice from a specialist or do a course of some description.
When ever I get to the point of building a van I will definitely get advise on protection and safety of electrical systems and oversize all my cables too.
Well done for putting this out there and well done for the person who gave you the advise, maybe the first comment could have been a bit more useful had it come with some information, If it is not constructive, criticism should be limited.
nobody from Fogstar mentioned the thing Neil has. Basically they want to sell you the batteries but they just cant be bothered giving you sound safety advice to fit it. Theres a whole spec sheet on Fogstar's site that accompanies each battery and literally NOWHERE on those spec sheet has anything covered by Neil's video. I find that very bad. Fogstar and other lithium battery firms need to pull their fingers out and give proper safety advice.
Wow scary 😮 Thanks Neil and Emma for putting this out to us all 👏 just ordered mine and again thanks for keeping us save ❤
lol maybe you should have read the comments first. The video is scaremongering.
Blimey 😳 sorry for not reading the comments but I have read up on the fuses they do blow quicker than the normal mega fuses you obviously know more than me so big respect but I also respect Neil's knowledge and experience for thinking of others ❤️.
I had a gel battery with a acid battery and the gel battery caused a fire
Hi guys, surely the battery manufacturer should provide this information to the buyer regarding safe and proper installation. Did you ask Fogstar regarding these fuses?
All the best guys
They do if you ask all the correct questions, however we had lithium in the van prior to getting our fogstar batteries and thought we had the right systems in place so didn’t ask if we needed anything else as we had been running off lithium for a few years. Someone who has bought from fogstar has all answers your question in the comments and they where given the correct advice and information
Maybe an idea to advise including some sort of fact/info sheet when supplying a unit. Just a thought
Having this type of fuse is a good idea, will have a look at my 270ah lithium setup in my van.
You do seem to be talking about lithium ion which is far more volatile than lithium LifePO4 which will not explode like you said. But I'm sure you are using LifePO4 lithium batteries. I do agree, be as safe as you can.
But I do get a little tied, OMG, you have lithium batteries in your caravan, aren't you scared they will blow up, no. Even had this talking to the builders of our new 12M marine rescue boat. We had in our specs, 300ah of lithium house batteries, they put in AGM, oh we are still on the fence with the safety of lithium.
I just about hit the roof, lithium are just as safe or even safer than AGM when using quality batteries, quality hardware and installed by qualified people.
Quality lithium batteries have a BMS and I'm sure you know what this is and this is first line of defense with any major faults with your battery system.
Sorry for the long rant, but I do agree, a class T fuse is a good idea, but where do you stop.
Emma here. We agree LifePO4 are safer and the BMS is the first line of safety but for us we just want to be as safe as possible, we didn’t know about these fuses for lithium as many others didn’t who we spoke to, but again that is down to user error (ie us not doing enough research when we had them first put in the van) to which we held our hand up, but also have learnt that BMS’s can also fail, so for us it’s about having another added protection. Many people fit things into their vans and do not know enough to be doing it so we wanted to raise some awareness for people to look into things.
Haha , Niel I'm in the process of as a beginner setting up and installing all my victron setup in my camper conversion. I have thankfully done the correct research and have purchased one of these a 350amp T class with 400amp fuse holder( it's a beast). Thought I was going overboard as as you said people were going its not a space ship . I told them that just as you said when using lithium a short could weld up and jump or arc on a mega fuse as a tremendous amount of amps more than the system could handle would happen if there was a short. The sand will suppress and prevent that. £100 for that in my mind is worth the the time and investment in your tin house. So Niel I must be in the weirdo area for fitting one ages ago 😂😂
Not all Lithium is made the same. LiFePO4 Prismatic Cells are very safe the don't just explode or set on fire like lithium-ion cells that scare the crap out of me every time I have to replace them. Plus the BMS if set properly just cuts off power anytime something happens out of spec, that being said I can't argue with having a proper fused system so I'll probably get one of these too.
A BMS is a computer & we all know how reliable computers are !
@@alanhat5252 Your brain is a computer and we all know how reliable computers are
Some commenters have mentioned that Fogstar has recommended additional fusing - If the manufacturer doesn't trust their own BMS, why should anyone else?
Also, if we ignore the BMS (Which would apply to any chemistry if we could trust it) - The chemistry doesn't really make it any safer. Here's a scenario:
1) You short out your LiFePO4 battery, the high fault current (6kA?) exceeds the interrupt rating of your fuse and welds it closed.
2) The battery heats and the fault current reduces, let's say 4-600A. The chemistry is "safe" so the battery itself doesn't combust.
3) You now have a continuous 4-600A flowing through your main battery cables, your failed fuse, your isolator and whatever else up until the short. We're talking about 240mm² to 500mm² cable needed to survive this without becoming a heater. (Sizes may vary depending on where you look, but it's big)
You're still going to end up with a major fire risk either way, just at different speeds.
A lot of people build their own vans & that’s why more campsites are saying no self build vans. Not everyone has your expertise in building your own van. Love your channel.
Iv never known any one being refused on a camp site to be honest . And I hope I never come across a site that dose that cos I’ll be telling them strait
@@UrbanVanlifeRick & Keira found one 😢
Thanks for sharing ❤ the day that you think you know everything is the day you die. l hope to keep learning for a long time 😊
Neil But is it as safe as thay say it is and how safe is it,
Arcing is from the voltage
Lol. Thata so funny and a drama.
1. They use victron...
Victron use mega fuses.
2. There lithium-ion batteries..
There not, theyre lithium fe-ion.. no blow up...
3. Could have got a ketto which is much less.
4. A battery Has a bms with current protection.
5 a full short will, blow a fuse and trip the bms. The bms will likely go back on, but the fuse will break the circuit.
It wont come back on with a short and welded fuse.
Now if you habe a lithium battery ... And you get a battery short (fairly common) you get a fire ball, but as they are internal no fuse is going to help you.
😢
If you do by chance, wire, fuse/breaker, correctly, then your unlikely to have any issues... Now this can be fairly rare from what ive seen 😊
Soooooo !!!!!! What happens if the BMS fails ???
1 cos they do
2 cables that are not fused will go on fire
Extra saftey is never a bad thing
@UrbanVanlife bms can and they do, but usually its a lower level of fault rendering the thing useless.
The new code is that batteries have breakers on them or in them.
I did mention cable fuses. But people can often put them in the wrong place... Far from the battery.
Fuses work and what you described with arching is higher voltage.
There is a table online
Nice one guys I’ve just ordered one!! Only fitted our new 628ah today too
@campervancodgers124 VIDEO FOR CHEAPER FUSE ALTERNATIVE
ruclips.net/video/tTtGNUk07ro/видео.html
12VOLT PLANET LINKS
FUSE HOLDER - www.12voltplanet.co.uk/blue-sea-systems-5007100-class-t-fuse-block-110-200a.html
T CLASS FUSE - www.12voltplanet.co.uk/class-t-fuses.html
I was nearly gutted when you showed the class T as they had gone completely under my radar on van build and on my boat rewire. Then you dropped in the quick pic of the terminal cube fuses which I fitted on all my pos terminals. So now I don't feel quite so bad, although being belts an braces I may well fit a class t on the main feed off the battery bank. Really glad you put this video out thanks
Not just what you have written..
A proper voltage drop calculation for each cable run..
Cable ventilation and no bundling etc..
Not just size but type of cable.. not AluCu and use copper lugs with copper cable particularly on heavy stuff.
The Boat Safety Standards might be an interesting read..
eg...
no soldering is a big one.. cables crossing fuel and gas ... also hot and cold.. and wear and sharp things.
Question is (which I'm going to put in a main comment)
What and why that size of fuse 😻
... too big?
Why only one etc.
Yep a little can be dangerous..
Why is their fuse, switch and battery exposed to impact?
Switch could be accessed from inside.. safer.
A full design is key.
the fogstar battery you have and 99% of current lithium batterys are in fact lifep04.. which is a completly different chemistry to old style lithium batterys which are quite volatile if treated wrongly ..lithium ion phosphate or lifepo4 for short batterys are far far safer they don't burst into flames when damaged like the old style lithium batterys ..the battery in your phone and laptop is more of a danger that the fogstar lifep04 battery..
Well explained Neil, did not know the massive current outage from a battery when at fault. This should protect the equipment in the van, some comments were saying they rely on the BMS built into the battery, well if that things melting then it will not help. Its important to realise that if the battery goes into meltdown, this fuse only protects the 12V circuits. Suggest some sort of heat or smoke detector near the battery in the garage. Another thing i do not understand is normally the output from solar panels is not fused at the solar panel, ask Daz as a short in the cable caused him nearly to lose his van. Why are they not fused?.
Solar wiring (I suspect) isn't fused on the outdoor part because it's extra connections to rot & potentially cause fires.
There should be a fuse (or reliable circuit breaker) in the circuit somewhere though!
@@alanhat5252it would appear not, Daz aka urban motorhome made a video after nearly burning his van down, drilled a hole, caught the wiring. And the voltage from the solar panels shorted out.
Does anyone know what fuse size I would need for a 280ahc lithium battery?
You need to work out what current your system draws, (wattage)then divide by the volts ie your battery 12v, then go a bit higher, I had a friend work mine out but believe 12 volt planet would help if you buy from them x
@ I have the correct size normal fuse on my system, but I’m hearing that you kneed some kind of huge fuse, which would not protect the cables, just stop the welding of the fuse holder, I’m conFUSED, to pardon the pun 😁
@@campervancodgers124 looking at the battery specifications, it quotes all the protection needed for theses issues
@@michaelwilliams3861 I didn't use the massive same fuse a Neil ours was a Mrbf, basically as I have much less stuff but, it made sense to me as from the battery to the fuse there was no protection if the fuse failed. I just went with my guy no harm In a extra safety which is why I'm attending a workshop in Hull on van electric safety on Saturday if your interested let me know and I'll give you the details I do know there is still places.
It depends on the spec of the BMS in the battery, if you want to draw 3000W for a 3kwh inverter, you would need a 250A-300A fuse to run that load and the batteries BMS would have to be able to supply that 250A of current or more to run it without dropping the BMS out on overcurrent protection.
IE: 12v x 250A = 3000W.
If for instance your batteries BMS can only discharge at a maximum of 200A for say 20-30 seconds or more, it could still run a 3000W inverter with a microwave up to 2400W, ie 12v x 200A = 2400W.
Hope this helps.
once again an informative vlog. , something i have noticed and wondered when seeing people upgrading to larger batteries is how many upgrade their kill switches to as they also have a maximum current load
It's hard to tell from the video but it looks like your disconnect switch is just a switch and not a fuse or breaker so yeah not having a fusing in line would be pretty bad.
It’s an isolation swich
Hi guys got my work van what is the best set up just to run a kettle/ microwave and charge up my power tools many thx 👍🇬🇧
Thanks for the heads up lad just ordered one 👍
I'm over the water I'd appreciate you having a look over my set up sometime when ur not busy... Andy 👍
I just came across this video. Well explained. I recently upgraded to two 460AH Roamer batteries . By shere luck. I went with the MRBF fuses, rated to the max draw if my circuit. I will look at the T-Class fuse, If I can find room. Thank you.
Thank you buddy
This is very well known in the boating world, is unfortunate that this has not got to the van world, the use of MRBF fuse is good for 12v, this was confirmed by Eaton who manufactures many industrial fuses. Much easier to install and actually protect cable from battery terminals. Also easier to get than T fuses. Bluesea also make buss bars for these like make installation simpler
I didn’t know this either 😢 which fuse range should you order? Great video❤
We got told 200amp fuse but I’d recomend talking to 12v plannet and see what they recommend
@ ok thank you ☺️ 🤗🤗💪
Hi I put a comment on Sam’s video when he fitted his Fogstar about these fuses and he said he’d look into it hopefully he did as he comes across as a guy who same as a lot of us does it right to the best of our knowledge at the time. I have two 280Ah fogstars in parallel so capable of delivering a lot more current (500A) than through one BMS so luckily bumped into the right guy when I was installing mine. Thanks for highlighting it and saving someone’s van and possibly lives.
Yer Iv spoken to Sam about them and he’s getting one fitted to his system
The latest here in Australia is the lipo batteries on new builds have to be housed in a metal sealed compartment with gas venting to the exterior , if the the RV is able to connect to mains power . Toxic smoke is a concern with a battery fault fire . The linked supplier have run out of stock , interesting .
Great safety video, I know zip about electrics, that's why I use ecoflow generator, found your last video about battery's interesting
Thanks for sharing
Emma yes safe is best but is it as safe as thay say,
For us it’s another layer of protection, and the correct fuse that should be used, there are other less expensive types which are just as safe but we couldn’t fit that in our set up due to space constraints but more safety in our opinion is never a bad thing!
I'm going to be that smug git now and tell you i did it right first time...
I use high breaking capacity fuses from the forklift industry. They operate under the same principle as the t class fuses you show, ie, they are filled with sand. The ones I have are rated for 10000 amps at 96v and I am using them at "48v nominal" which for me works out to be around 54v give or take...
In theory the BMS inside the battery should give you an amount of protection, but the fuse is a last resort in case the MOSFETs fail. I wish battery manufacturers had the forethought to include fuse protection to their BMS systems, but there we go...
Good to know! Thanks. But. I'm going to use a Bluetti- like set up for my electrics.
I had tried to find T ratted fuses but was coming up blank.
Thanks for the information.
All the links are in the description mate
It’s called a class t fuse not t rated
Completing merc vario build and all I’ve read never heard of this. It will now be included in the system. Great vid and advice 👍
Most modern vehicles are fitted with a Pyrofuse to protect the multiple electric circuits and management systems.
True story ,
Wow a big big thank you Like you said we could lose the lot thanks
Hi. So are u saying that you’ve NEVER used fuses on your batteries system in the past OR you have but not the correct type and relied on the BMS? I have inline fuses on my lithium LiFePO4 set up, just not the one you mention, as I have never heard or had it recommended in the past. Thanks
Hi we have always had fuses on our system, we where unaware that we needed to have the additional fuse for the lithium battery installed as we had previously had our lithium battery prior to the fogstar ones installed by professionals and these fuses where not mentioned when they fitted and installed it.
If you use lifepo4 batteries with a built in BMS, in the event of a short circuit the BMS will reach its maximum output and shut down, so a mega fuse should be ample as the fuse would faail and the BMS shut off the power. There arent many people fitting the expensive fast blow fuses.
If your happy with the built in bms that you can’t see and don’t know if it will or will not break the flow then that’s ok . Personally for the money we have spent on our van a little extra level of saftey for under £100 then I’ll take it . Guess it’s each to their own . And there arnt many people fitting these fuses that’s correct . But there are also people still fitting Amazon breakers and not mega fuses . I just know when it comes to saftey I’ll feel a lot happier with more than less
Remember the class t has two used, 1) protect from an overload of the rated amps - so in this vid its rated at 200amp. 2) Protect from a short somewhere after the class t as if this happens the battery will dump its entire contents in a split second, this fuse will not only blow because it goes over is rating but then stop an arc happening which could very well in a bms unless its been potted (Victron?). Not only does it protect you if faffing on the electrical system and you're waving leads around, but what about in an accident who knows whats going to get damaged etc. Its food for thought, so like UV I designed my system with one in place and its connected about 10cm from the battery positive before then connecting to the bms etc.
Safer Emma & Neil knowing that you both sleep above it to during the night ❤
As an idiot who has accidently ( clumsily ) shorted out his 12 volt LifePo4 , it never caused an Arc but instead blew the spanner apart in one big bang before I knew what was happening , so my mega fuse "spanner" saved my battery going boom 🤣
Great info. I appreciate it. On a side note, what's the projector behind your head
lol it’s the wimius k9 buddy
Good video. What amp size fuze did you buy please? 😎
We were advised a 200amp but that’s for our system . I’d ask 12v plannet that are great for advice