For low-amperage (10-30A) high voltage-fuses you can use 10x38mm ceramic fuses, also known as solar PV fuses. These are ceramic fuses ... basically a miniature version of a T-class fuse, and typically have an I.R. of 20,000A @ 1000VDC. Note that many people improperly use auto blade fuses and glass fuses in battery systems. These fuses are generally only rated to 32V and have very low IRs, so they are only suitable for use when placed after a breaker or other fuse that breaks/blows below their IR. So blade and glass fuses should never be directly hung off of a battery bus or used in higher-voltage systems. Use 10x38mm ceramic fuses instead. ICC vs IR: You used ICC when you should have used IR in most places in your video: -- ICC (Rated Short-Circuit Current): This value represents the highest current a circuit could experience during a short circuit, and is typically used to ensure the chosen fuse has a sufficient interrupting rating to handle that current safely. IR (Interrupting Rating): This is the maximum current a fuse can safely interrupt without damage or failure, and is usually expressed in kiloamperes (kA). -- You made a mistake on your Class T table. Class T fuses typically have an I.R. in excess of 200,000A (200kA), not 20,000A (20kA). Most BMS's *ARE* designed to properly disconnect on a short-circuit. You need the fuse as an added layer of protection because if the BMS's FETs burn out, they likely burn-out into a crowbar'd state. So the fuse is mandatory, but the BMS is still supposed to be the first line of defense. On a large battery bank, a large wire gauge (i.e. a small wire) may effectively limit the amperage during a dead short and prevent the BMS or the main battery fuse from blowing even as the wire catches fire. Thus, all cabling must be properly sized to ensure that the BMS and/or fuses blow if a short occurs, and proper breakers or fuses must be used when branching into lower-amperage satellite circuits that are using smaller cabling to protect that cabling, since a short on the smaller cabling may not trip the main bus fuses. -Matt
- Yes, you can see these ceramic fuses being used in solar combiner boxes. - Indeed, that's why the voltage rating of a fuse is important. - Yes, I used ICC during the video, I didn't want to confuse people more than i needed to, but you are right. - Class-T have 20 kA @ 125 Vdc and 50 kA @ 160 Vdc so it depends if it's AC or DC. Also depends if it's a JLLS or JLLN (by littlefuse). - I wouldn't trust on electronics to break a short circuit current. Thanks for your constructive feedback Matt. I really appreciate the healthy discussion.
According to test, Winston 40Ah cell produced an initial peak current of about 2200A during a short circuit, exceeding its rated capacity by over 55 times. Therefore, your assumption of 10 times is incorrect, at least for Winston cells. Test video available here: ruclips.net/video/R9xZf4p8PkQ/видео.html
That is a good remark. Generally lower capacity cells have less internal resistance, thus create a higher current. The internal resistance of a 40Ah winston cell is 0.0007ohms. So this becomes: 3.2V/0.0007ohm=4,571A potential short circuit current (more than the shown current). I should have mentioned my tests with my 12V 100Ah and 200Ah battery. You can see the internal resistance is not only the current of one cell. it's the cells + contact resistance + bms internal resistance + lug resistance + cable resistance. In my video about paralleling different capacity batteries my 12.8V 100Ah battery measured 11.4milli ohm or 0.0114ohms. 12.8V/0.0114ohm=1,122A of potential short circuit -> a bit higher than 10x. The 200Ah battery measured 8milli ohms or 0.008ohms. 12.8V/0.008ohm=1,600A -> lower than 10x. So it's incorrect tot measure the short circuit voltage of a single cell because the current has to pass the fuse in order for it to break the circuit, and on the way to the fuse it has to pass trough the bms, lugs, busbars, cables, and the fuse itself. additionally, if we reverse-calculate the internal resistance of the test: 3.2V/2,200A=0.00145ohms or 1.45milli ohms. The resistance is very low because of the huge cables they are using, the single cell,... so the test is not a real world scenario.
Excellent video. Thanks. I have several of these batteries... LiTime 12V 100Ah BCI Group 24 LiFePO4 Battery, 100A BMS Rechargeable Lithium Battery with Up to 15000 Cycles. It purports to handle short circuits. The Amazon product description says "... the battery is protected from overcharging, overdischarging, overcurrent, overheating, and short circuiting by a powerful BMS.". I thought that the BMS's were adequate due to this. "The BMS on lithium batteries disconnects the load/charge by the use of MOSFETs, these MOSFETs are commonly the limit on the continuous current rating of the battery. If the battery is rated for 100A continuous, and you have a 2000VA load, then you will be drawing approximately 167A from the battery and you will destroy the MOSFETs almost immediately.". Does this BMS give inadequate short circuit protection, requiring the additional fuses you discuss? If so, how and why?
Can you make a solar/wind generator/diesel motor alternator setup for sailing boats? Would be much appreciated! Not only based on lithium batteries, but also AGM batteries.
I have several systems in my playlist, go check it out. I don't recommend wind, it's not as good as they make it seem. Why do you want to use AGM batteries? I have a video about it coming soon where i compare the price (AGM=8 times more expensive).
@ TYes, I saw. I thought maybe for sailing there might be other aspects I would have to consider due to the environment. Wind because of the fluctuations? Is there a way to compensate? I want to sail around the world and therefore looking to utilize any means of producing electricity. Solar might sometimes not be an option with bad weather conditions or just less sun. I was also looking at hydrogenerators. I am struggling what kind of batteries. I want the safest option. A fire would be the end of my sailboat.
You must use properly rated fuses/breakers and you see so many people using entirely inappropriate ones. I still see people putting incorrect fuses before the BMS as an additional protection where the SCC will be quite large. The total of all impedances at play soon limit the real world SCC on the outside but that total of all impedances must consider parallel batteries too. If you have 3 x 2kA of SCC coming into your bus bar the outgoing protection has to be able to cope with it.
Of course battery construction comes into this too, and the problem is where is person off the street has no idea of their battery being built from high capacity prismatic cells, a collection of smaller prismatics, or even a large collection of cylindrical and has no understanding of what the SCC actually is assuming they even understand the need for OCP. It's not without reason that I said what I did about SCC and fuse choice on another video.
Hi man. First, thanks for all your videos... I know this question is not related to this video but I need help with something... My inverter only charges the battery with my generator only when is a load of over +/-500w. If there is no load at all the inverter will not charge the battery.
I suspect that your battery is already full or you set the wrong parameters. Do you have a shunt? If not, i recommend adding one, its shows battery capacity correctly. I made a video about it as well. Search for shunt.
@cleversolarpower I dont have a shunt yet, the batteries are fine. The problem is that the generator produces power when is demanded and and inverter takes power when is available, the inverter doesnt trigger the bypass until the load is over 500w and the power from the generator goes to the load and whatever is left to charge the battery, I can not make the inverter to charge the battery only with utility/generator...
@cleversolarpower I been looking for a shunt, I have 8x U-Power UP-TFS250-12, they are 12v 250ah, the are connected as 4x 24v so I think I need a 1000amps shunt?. Thank for your help.
Not sure about the differences. Good brands don't use the term NT00. Maybe NH00 is a protected term only used by good manufacturers and NT00 is used by other sellers. I would only trust NH00 from popular manufacturers listed in the description.
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MEGA: amzn.to/4hWSIJE
MEGA 70V: cleversolarpower.com/go/70VMEGA
ANL: amzn.to/4hYo6Y8
MRBF: amzn.to/4hZOL6T + amzn.to/4hYo96g
Class-T: amzn.to/3CGkRV9
NH00: Siemens, Bussmann, or Eaton
Just bought your book! Received it today. Great information!
For low-amperage (10-30A) high voltage-fuses you can use 10x38mm ceramic fuses, also known as solar PV fuses. These are ceramic fuses ... basically a miniature version of a T-class fuse, and typically have an I.R. of 20,000A @ 1000VDC.
Note that many people improperly use auto blade fuses and glass fuses in battery systems. These fuses are generally only rated to 32V and have very low IRs, so they are only suitable for use when placed after a breaker or other fuse that breaks/blows below their IR. So blade and glass fuses should never be directly hung off of a battery bus or used in higher-voltage systems. Use 10x38mm ceramic fuses instead.
ICC vs IR: You used ICC when you should have used IR in most places in your video:
--
ICC (Rated Short-Circuit Current):
This value represents the highest current a circuit could experience during a short circuit, and is typically used to ensure the chosen fuse has a sufficient interrupting rating to handle that current safely.
IR (Interrupting Rating):
This is the maximum current a fuse can safely interrupt without damage or failure, and is usually expressed in kiloamperes (kA).
--
You made a mistake on your Class T table. Class T fuses typically have an I.R. in excess of 200,000A (200kA), not 20,000A (20kA).
Most BMS's *ARE* designed to properly disconnect on a short-circuit. You need the fuse as an added layer of protection because if the BMS's FETs burn out, they likely burn-out into a crowbar'd state. So the fuse is mandatory, but the BMS is still supposed to be the first line of defense.
On a large battery bank, a large wire gauge (i.e. a small wire) may effectively limit the amperage during a dead short and prevent the BMS or the main battery fuse from blowing even as the wire catches fire. Thus, all cabling must be properly sized to ensure that the BMS and/or fuses blow if a short occurs, and proper breakers or fuses must be used when branching into lower-amperage satellite circuits that are using smaller cabling to protect that cabling, since a short on the smaller cabling may not trip the main bus fuses.
-Matt
- Yes, you can see these ceramic fuses being used in solar combiner boxes.
- Indeed, that's why the voltage rating of a fuse is important.
- Yes, I used ICC during the video, I didn't want to confuse people more than i needed to, but you are right.
- Class-T have 20 kA @ 125 Vdc and 50 kA @ 160 Vdc so it depends if it's AC or DC. Also depends if it's a JLLS or JLLN (by littlefuse).
- I wouldn't trust on electronics to break a short circuit current.
Thanks for your constructive feedback Matt. I really appreciate the healthy discussion.
👍
I just bought your book. Great videos...
Thanks for your support!
According to test, Winston 40Ah cell produced an initial peak current of about 2200A during a short circuit, exceeding its rated capacity by over 55 times. Therefore, your assumption of 10 times is incorrect, at least for Winston cells. Test video available here: ruclips.net/video/R9xZf4p8PkQ/видео.html
That is a good remark. Generally lower capacity cells have less internal resistance, thus create a higher current. The internal resistance of a 40Ah winston cell is 0.0007ohms. So this becomes: 3.2V/0.0007ohm=4,571A potential short circuit current (more than the shown current). I should have mentioned my tests with my 12V 100Ah and 200Ah battery. You can see the internal resistance is not only the current of one cell. it's the cells + contact resistance + bms internal resistance + lug resistance + cable resistance. In my video about paralleling different capacity batteries my 12.8V 100Ah battery measured 11.4milli ohm or 0.0114ohms. 12.8V/0.0114ohm=1,122A of potential short circuit -> a bit higher than 10x. The 200Ah battery measured 8milli ohms or 0.008ohms. 12.8V/0.008ohm=1,600A -> lower than 10x. So it's incorrect tot measure the short circuit voltage of a single cell because the current has to pass the fuse in order for it to break the circuit, and on the way to the fuse it has to pass trough the bms, lugs, busbars, cables, and the fuse itself. additionally, if we reverse-calculate the internal resistance of the test: 3.2V/2,200A=0.00145ohms or 1.45milli ohms. The resistance is very low because of the huge cables they are using, the single cell,... so the test is not a real world scenario.
@@cleversolarpower 👍
valuable information.. thumbs up and appreciated!
Excellent video. Thanks. I have several of these batteries... LiTime 12V 100Ah BCI Group 24 LiFePO4 Battery, 100A BMS Rechargeable Lithium Battery with Up to 15000 Cycles. It purports to handle short circuits. The Amazon product description says "... the battery is protected from overcharging, overdischarging, overcurrent, overheating, and short circuiting by a powerful BMS.". I thought that the BMS's were adequate due to this. "The BMS on lithium batteries disconnects the load/charge by the use of MOSFETs, these MOSFETs are commonly the limit on the continuous current rating of the battery. If the battery is rated for 100A continuous, and you have a 2000VA load, then you will be drawing approximately 167A from the battery and you will destroy the MOSFETs almost immediately.". Does this BMS give inadequate short circuit protection, requiring the additional fuses you discuss? If so, how and why?
Do you have a source for the fuse block for the mega fuses shown in the parallel layout shown at 6:39?
Google victron fuse busbar 😉
So is the BMS not able to stop the short circuit current? My 280 Ah battery's BMS says maximum current discharge is limited to 1000 amps.
It's definitely not designed to do so.
love the videos... what size n type fuse for 280 ah battery.. or a dc breaker
If its 12 or 24V, use an ANL fuse. If it's 48V, Class-T or NH00. You can always use fuses that are rated higher (use Class-T or NH00 instead of ANL).
@@cleversolarpower hi its 12v..... i was wondering what size fuse ??? amps
@@Mmmmmmmiwish I have a video on selecting fuse size, you can search for it on my channel page.
@@cleversolarpower cheers .. will check it out
Can you make a solar/wind generator/diesel motor alternator setup for sailing boats? Would be much appreciated! Not only based on lithium batteries, but also AGM batteries.
I have several systems in my playlist, go check it out. I don't recommend wind, it's not as good as they make it seem. Why do you want to use AGM batteries? I have a video about it coming soon where i compare the price (AGM=8 times more expensive).
@ TYes, I saw. I thought maybe for sailing there might be other aspects I would have to consider due to the environment. Wind because of the fluctuations? Is there a way to compensate? I want to sail around the world and therefore looking to utilize any means of producing electricity. Solar might sometimes not be an option with bad weather conditions or just less sun. I was also looking at hydrogenerators. I am struggling what kind of batteries. I want the safest option. A fire would be the end of my sailboat.
You must use properly rated fuses/breakers and you see so many people using entirely inappropriate ones. I still see people putting incorrect fuses before the BMS as an additional protection where the SCC will be quite large. The total of all impedances at play soon limit the real world SCC on the outside but that total of all impedances must consider parallel batteries too. If you have 3 x 2kA of SCC coming into your bus bar the outgoing protection has to be able to cope with it.
Of course battery construction comes into this too, and the problem is where is person off the street has no idea of their battery being built from high capacity prismatic cells, a collection of smaller prismatics, or even a large collection of cylindrical and has no understanding of what the SCC actually is assuming they even understand the need for OCP. It's not without reason that I said what I did about SCC and fuse choice on another video.
Yes, increasing the internal resistance of the battery slightly will reduce the short circuit current.
Hi can i use a 125 megafuse on a 48 volt system with pylontech 5000 battery on a victron power in ,or do need a class t fuse not quite shore thanks
You need a 70V MEGA fuse, a Class-T, or NH00 fuse. Your battery is 48V at 100Ah.
OK thank you heaps
😮I have NH01 350a fuse 250a circuit breaker in my system.. is quite big. NH00 fuse at 160a in my small system
I have the exact battery and inverter for the portable kit I'm building :)
I already purchased the megafuse but if not correct i will purchased the correct fuse thanks
Hi man.
First, thanks for all your videos...
I know this question is not related to this video but I need help with something...
My inverter only charges the battery with my generator only when is a load of over +/-500w.
If there is no load at all the inverter will not charge the battery.
I suspect that your battery is already full or you set the wrong parameters. Do you have a shunt? If not, i recommend adding one, its shows battery capacity correctly. I made a video about it as well. Search for shunt.
@cleversolarpower I dont have a shunt yet, the batteries are fine.
The problem is that the generator produces power when is demanded and and inverter takes power when is available, the inverter doesnt trigger the bypass until the load is over 500w and the power from the generator goes to the load and whatever is left to charge the battery, I can not make the inverter to charge the battery only with utility/generator...
@cleversolarpower I been looking for a shunt, I have 8x U-Power UP-TFS250-12, they are 12v 250ah, the are connected as 4x 24v so I think I need a 1000amps shunt?.
Thank for your help.
So ANL is for 24v/280Ah?
No, it's in the table.
I have a fuse related question please.
Do you know what the differences are btween nh00 and nt00 fuses?
Not sure about the differences. Good brands don't use the term NT00. Maybe NH00 is a protected term only used by good manufacturers and NT00 is used by other sellers. I would only trust NH00 from popular manufacturers listed in the description.
cool
Когда ролик начинается с наратива "Вы делаете НЕ правильно", это видео получает "палец вниз" и "НЕ рекомендовать этот канал"
Think Elon, use a pyrofuse!
DAM WHY THESE FUSES COST SO MUCH NO WONDER WHY PEOPLE KEEP BUYING THOSE CHEAP CRAP EBAY FUSES BEACUSE WE CANT AFFORD A GOOD FUSE
Checkout my video where I test several mega fuses and see for yourself 😉