I have been trying for over a year and have had various technical guys look at the DC to DC charger..... no one got it installed in my travel trailer (carvan) working correctly. Your video solved the problem. The final missing piece is the grounding of the negative. This allowed the LC to reduce the amps by 50 %. Finally, I can tell Renogy to close their file.... and watch your video.😊. Guess the Aussies are smarter than all the Canadian tekkies.😅
You're welcome! Yes I'm sure that is not well understood and I have often heard of fuses blowing because they have not allowed for the overheads (inefficiencies) of these converters through low voltage input due to cable losses.
I tested this only yesterday while away camping to see what the current draw was at 40A output charge rate and its 50 amps input from the car alternator. This is due to some inefficiencies but also the voltage drop over the cable run from the vehicle alternator/cranking battery to the charger in the van (about 10 meters of 10mm cable). The DCDC charger has to boost the voltage up from say nominally 12 volts input (possibly lower at that current) to 14.6 approx output (the correct bulk & absorption charging voltage for AGM and lithium batteries. So the input current will always be significantly higher than the rated output.
Bit of an update - I was on the road for about 7 weeks in July-August with quite unseasonally hot weather in Northern Australia with 3 weeks of over 35C everyday. We relied on this to maintain the batteries and this charger has done a great job - with one exception- the ignition sense has failed and have contacted Renogy but its a bit hard testing it while we are moving everyday or so. I told them I will look at it when I get home as it really doesn't inconvenience us at all.
I considered the DCC50S but after reading the specs very carefully, I understood that it would only output 25 amps from alternator and 25 from solar. The 50 amp rating looked to be a combination of the two inputs. Like you, I prefer a separate DC to DC charger and a separate solar charge controller rather than a combination unit. I ended up with the Renogy 40 amp DC to DC charger and an Epever 40 amp Triron controller. I'm really happy with the end result, too. I'm running 4S2P 125ah LiFePo4 with 100 amp BMS's and it is rock solid! Your explanation of the constant current charge using to Renogy DC to DC is spot-on as well. Good video. Thanks for putting it out for us to see.
Thanks for your feedback. I'm running a Renogy 30 Amp Epever solar controller in this new setup and very happy with the result. A friend recently had an issue with an "all in one" Projecta PM435 when it failed and that left them with no power at all including the fridge and no way to charge the batteries. Turned out to be a simple issue in the end but highlights the vulnerability with these one stop solutions.
I have been charging with shore power via a server power supply for many months via the Renogy 40amp, and it's perfect, no issues at all and it's consistent and reliable. The PSU was 15 pounds from eBay. If people want to spend 10x that on a victron or a Noco then ok, but the PSU puts out 52amps at 13.2v the dc to dc max is 40amp and the whole thing works very well together. 480 to 510 watts well👍
I was surprised there is no delay when it see's 12v @ the D+. It starts pulling 50+ amps from start batteries. I put mine on a 3 way switch off/20/40, feeding 12v from ignition. gives options and time to start motor without compromising start bank. Why there is not at least a 5-10 sec delay is beyond me. Im on a boat so I need a bit more time to start up motor before this thing pull amps from start batteries. Nice video thanks !
I’ve just bought one of these and I think I’ll put a switch on the current limiter wire so I can easily change to 40amps only when I really need to AND I think (would like) to connect it to my headlights so it only turns on when I have the headlights on. So it’ll only work when there’s no more sun on the panels and if I need it thru the day, I’ll just put the lights on. Dunno if that’s a good idea or not? I do like the voltage drop relay but don’t know how to wire that up. EDIT: my initial thoughts was not the best idea. In the end, I just connected it to a 12v source that isn’t active after the car is turned off as recommended, but also installed a switch to turn it on or off while the car is on as 99% of the time, I don’t need it. At first I thought it was a real hassle having to wire up that 12v wire, but I actually love it. And it works really good so far. 👍
I would be inclined to run it a 20A is you run it when the lights are on as you want to limit the load on the alternator as much as possible. Most alternators are not designed for a constant high load current as is the case with these chargers. I would only run it at 40A if the battery was dead flat and I needed it to recover quickly. I would only run it at 40A is I was driving at highway speed to keep the alternator from overheating.
@@timterry8714 yeah you’re right....after I posted my comment, I realised it’s probably a stupid thing to wire it to the lights. Currently, I’ve just wired it as recommended to a 12v source thats only with the ignition on. I’m then going to wire in 2 switches, 1 to manually control it to 20 or 40 amps, and the other to turn it completely off. I think during full sun days, which is most days, I won’t need it at all.
Yep, have mine on a 3way off/20/40, otherwise this thing pull 50+ amps from start batteries as soon as it see's 12v @ the D+ wire. no delay. I want time for motor to start, and warm up.
@@sr7486 its a separate switch you connect to the terminals. Normally you would have 2 switches. One is the ignition, the other is to go from 40 to 20 amp. If you use a 3 way switch for 20/40/off, you need a diode between center pin and D+
Boost mode, lower voltage in, higher voltage out. Buck, high voltage in, low voltage out. Thanks for the video. This is just what I'm looking for to avoid blowing up my alternator.
Yep the boost function works really well on this model - much better than the DCC50S which doesnt work in the alternator mode unless the voltage in is well above 13 volts to achieve a usable output.
Had a problem with mine, my first 40 amp renogy stop working on just a 400-mile trip, I did notice it was pulsating voltage that was going into my house batteries, they sent me a replacement, check that today and it is still sending a pulsating voltage. 20-amp renogy I had previously, failed after about a year, so I ordered another 20 amp renogy, and now that I've jumped up to the 40 amp renogy I'm using the 20 is a backup. The 20 never pulsated the voltage, does that sound right with the 40 amp
I havent seen that issue so cant comment unless its an equalisation function you are seeing which is for Lead Acid batteries and shouldnt be present for Lithium. Check battery type setup as per manual. Otherwise not aware of that issue.
I bought one of theses, the 20A Renogy DC-DC on board battery charger, model DCC1212-20. I placed a 30A breaker on the pos line from the starter battery to the device, as per the instructions. However, the breaker keeps flipping. I changed it out, but the new one keeps flipping. So this device is not charging my house battery because of this. I have a 150 amp alternator. Before I bought the device, I called Renogy and was told to buy the 20A device. Now, the Renogy customer service number hangs up after it plays the initial introduction message. What do you recommend?
I would have thought you should have a bigger breaker than 30A as the charger can draw about 25 amps from the vehicle battery to output 20A. I would have a 40A breaker. I use a 70A for my 40A charger and 40A for a couple of 20A chargers I have installed. Does it trip instantly? If so thats indicating an issue - if it takes a few seconds it may be that the breaker is to small. Also as the input voltage drops below 12.5 volts the input current will increase to maintain output voltage (see video) the cable maybe a bit undersized causing voltage drop, higher current, breaker trips! Also some breakers have very poor accuracy unless they are properly designed very expensive DC low voltage breakers. I would try a much bigger breaker or better a ANL fuse.
@@timterry8714 Renogy said to use a 30A breaker, but the 30A manual reset breaker I bought, as it turns out, was opening at less than 30 amps. I replaced the breaker with a 30 amp automatic reset circuit breaker...everything is working ok now.
I run it at 20 amps as thats all I need most of the time and importantly to reduce load on the alternator. At 40amps out the alternator has to supply approx 55 amps input continuously and thats not good for it. I only run it at 40 to catchup when the battery is very depleted and I'm highway driving to keep the alternator cool under this continuous high load.
Just wanted to say thanks for this video. I've been looking all over the place for more detailed operation on this unit and you got the job done. Thanks!
I submitted a Q to renogy via their support website : How many amps reach the leisure batteries when 1. Engine running (50amps available ) and 10 amps of Solar are also available 2. Engine not running and 40 amps of Solar is available. A1: DCDC charge controller will attempt to maximize the solar input first. It will take as much power as possible from the solar panel (up to 10 amps in this case) before supplementing it with power from the alternator. So, the leisure batteries will receive up to 10 amps from solar, and the remaining power required to charge the batteries up to their set voltage will come from the alternator (up to 40 amps) A2: If the engine is not running, and you have 40 amps of solar input, the DCDC charge controller will utilize the full 40 amps from the solar panel to charge the leisure batteries.
Hey Tim Once again enjoying another another of your informative well explained clips. Awaiting delivery of my caravan and have decided to organise my own battery/dcdc charger and solar setup rather than factory gear. Intrigued to hear your suggestions on what renogy products to install to support a 12volt compressor fridge (ThetfordT2175) with y given your learnings and experiences. Currently considering 200 amp lithium batter, this 40 amp charger, a separate solar regulator with 200 watts fixed solar and 200 watt solar blanket. Any other suggestions welcomed cheers.
I recently installed a Bushman 190Ltr compressor fridge to replace the disaster Dometic 3 way fridge that came with my caravan. The 200A/h's of Lithium Batteries supported by 2 x 175 watt Renogy Flexible solar panels and a portable folding 300W panel have proven to be more than capable of supporting the Bushman (even without the portable panel being required most of the time). I also now run a Breville Coffee machine via a 2Kw inverter, occasionally the microwave and washing machine. If I had the space on the roof I probably would have opted for a 3rd 175w panel but at this stage it seems unnecessary in most situations. Having said that this years terrible weather has certainly tested the capacity to the limit - but so far so good. I also have the 40A Renogy solar controller which I covered off on another vid here elsewhere. I very happy with this setup and the 40A Renogy DCDC charger (95% of the time it is only ever run at 20A charge rate). So I think you've got it covered off prety well. Cheers Tim
best part of your video is youve done something nobody has done,used a seperate power source to charge another battery bank.I have 2 solar systems on my trailer and I could use the one not used but for lights to help out my other battery ban.
Thank you, sir. I'm setting up my rig with an inverter system for the first time. I was looking at this unit in particular to supply the correct charging voltage for two ≈120 ah marine batteries in a battery box I will fabricate soon. Cheers, brother! 🍻
Tim - A common problem folk have with these units is that folk fit 30amp breakers to 20amp units and they trip on start up - this is due to two phenomina - When the engine starter is engaged the engine battery voltage dips due to the extreem load, causing current to rise as you clearly showed, combined with the inductor & capacitors in the Renogy unit which cause demand to spike - The combination of both can exceed 30a momintarily - I use a 20a unit wired with 7AWG and a 40a Maxi Fuse and the unit has worked flawlessly
@@timterry8714 I still think your marginal on that 30amp breaker especialy when your house battery is at near full and cold thick oil dips your engine battery on a colld morning start up - good luck
Hey there. Great Vid. I just bought one of these. Hooked it just as you have done - it is limiting the charging amps perfectley at 20 amps. Now how do i get the full 40 amps ? I took out the LC wire and amps don't change at all - still sits at 20 amps ? Am i missing something here ? any help would be great - i have contacted renology but havn't heard back from them yet.
Hi Andrew, I had a fault in one of these where it was ignoring the D+ input and working all the time regardless of whether +12 was on that terminal or not. I raised a job ticket with Renogy about this and after a few email back and forth and a short video demonstrating the problem they sent me a replacement - so you may have the same issue. It sounds like its clearly not seeing a change of state from the +12V input to the LC terminal. I fed mine from the +12V input terminal by the way. Cheers Tim
Thanks for a well presented test. May I ask what size alternator is in your vehicle? Would rather charge at 40A than 20A, if my 160A alternator has enough spare capacity.
Not sure but at least 100A. Its the constant load that's the issue. Being able to deliver Hi current for a short time is normal in a vehicle but its the continuous hi current load for hours thats the issue.
The start battery is protected by installing a VCR to isolate the charger after engine shutdown, or installing an ignition sense wire to D+ terminal. But this one does charge properly.
Yes, definitely but remember its a vehicle charger only does not have a solar input. I prefer to have separate chargers to provide redundancy. Dedicated solar controllers have lower overheads (lower internal power consumption) also thereby providing greater efficiency.
@@timterry8714 yes on my ctek I only use it for alternater charging because max amps are only 20 with solar or no solar so I wanted 20 from alternator and what ever I can get from seperate solar charger.
He probably ran it at half amps because as he turned voltage down the amp pull would have exceeded his power supply. Just a guess. I do wish you would have measured output voltage too.
Hi Oliver, I run it at 20 amps to decrease the load on the car alternator and I dont need the higher capacity at the moment as I only have a 100Ah battery. I purchased a 40 amp in thinking that I may increase the battery storage at sometime in the future and would the look at utilising the extra capacity. It seems to keep the battery fully charged even while running the 3 way fridge while driving.
I very recently decided to upgrade to 200A/h of lithium as its quite reasonably priced now and I will add a switch to the current limit input port so I can select either 20A or the full 40Amps if I need to really boost the battery after several days of no sun which I recently experienced. I will normally only run at 20A to minimise load on the alternator.
Yes C5turbo, it does output a full 40A and I demonstrated that in the video. It achieved full output all the way down to around 9.5 Volts at the input terminals which is very impressive. With the current limited it sat at approx 19.5A output over the voltage operating range specification.
Just a light gauge wire and yes I have a switch in line to enable/disable the charger. I actually tied the D+ to the +12v input via a switch so it starts as soon as I connect it to the vehicle. The switch is actually a voltage controlled relay so it shuts down the charger at 12.8V.
Omg!!! I have been watching these videos for months to understand!! I finally understand ! Thank you so much ! I have a qustion can I hook it up to my started battiery ? Or dose it have to be from my alternator?
Glad it was helpful. The input to a DCDC charger is from the starter battery positive and a solid connection to the chassis (for the negative). Do not connect the negative to the battery negative. Cheers Tim.
Holy s you just convunce me to get 40amp dcdc charger .i was wonder wich ine to get that would work good .and man you showed me exactly what i wanted to know.thank you so much ..i was going to make a small generator out of weedwaker engine.might still do it but u helped me decide greatly....
It gives you options. I have mine installed with a 3 way switch. off/20/40, this way you can pull only 20 if you are running the engine at low RPM's or if you just want to slowly charge the bank, or if you want to put less stress on the alternator. Without the switch, and set for 40 amps, the unit pulls about 50+ amps from your start battery as soon as it see's 12v at the D+ wire. There is little to no delay (should have been a 10 sec.. delay in my opinion, to get the motor running). I switch mine on at 20amps once the motor is well under way, then switch to 40amps once at cruising speed if needed. installed on a yanmar 15hp w 80 amp alternator. Cheers
I agree completely with the above comment - the alternator load is an issue unless the vehicle has had a high current or heavy duty alternator installed. I have only run mine at 40 amps once when my battery bank was totally depleted after I left my 3 way fridge on DC all night. I was traveling at highway speed 100kms/hr the entire time so the alternator was able to stay cool - definitely would not run it at 40 amps if I was driving in the city at low speed and stop/start or in high summer temps.
I always thought that Renogy was squarely aimed at the American RV market so caravans and voltage drop probably isn’t something they care about so much.
I had one of these things I found the fans to be very low quality and they started making a noise after about a year it just kept getting worse and worse
I havent heard the fans running and making any excessive noise as yet. Not sure that would be an issue really as this charger is only running when we are driving and as its in a caravan no one is in the van when its being towed.
These are designed for both smart and dumb alternators. They work down to about 10 volts input (smart alternators run around 12.5 volts). You need to install an ignition sense wire to shut it down when the vehicles is stopped and that is connected to the D terminal on the charger.
@@timterry8714 The only downside on that dc-to-dc charger That I can think of is It is Drawing current as soon as you start your vehicle . If you could put in a programmable time delay relay You could program it so it wouldn't start charging Until you know your starting battery is charged up . I installed one on my side by side . For some reason the manufacturer thought it was a good idea That the radio should turn off after 1 minute When the ignition key was turned off . Not so great if you want to listen to the radio When you are parked The one I bought you can set It up for all kinds of programs . You can set it for whether the ignition is cycled off or when it's cycled on it starts Counting . I have it set for an half hour Then it turns off the radio I can program it for however many hours I Want it to run . If it turns off all's I have to do is cycle the ignition key and give it a 12-volt trigger It comes with a built-in 10 amp relay . It's a neat little device and I think it was only $20
@@bucket1249 What does it matter ????Who cares if its drawing current ( I presume you mean Main battery charging current) as engine is running.......The reason people want me to instal these devices is for exactly that reason..........Your Main battery is still going to come up to charge , probably long before the Aux battery will because the starting discharge generally bugger all re its capacity....
@@grahamhastie896 I'm just thinking about people who have puny alternators in little cars and trucks it it'll charge but it's going to take a toll on your alternators after a while
Do not buy this product! The warranty and customer support is the worse I have ever seen. Did not work from day one. Thank God for Amazon, they helped, but Renogy did nothing. Very poor customer service.
Hello I recently bought and installed a renogy dc-dc 40A according to the instructions. Why does the 60amp fuse blow? after 10-15 minutes The cables are 35mm2
@@timterry8714 I installed automatic fuses from Amazon Do you think I should put 100amps? I'm afraid that something will burn Thank you for your quick response👍
@@jaca2107when u say automatic fuse,do u mean a resettable circuit breaker? If so, then yeah, go to a 80A-100A circuit breaker, especially if under bonnet as the extra engine heat can cause these CB’s to trigger earlier than specified and the cheaper versions can also be out of spec & trigger under much lower current usage than specified. Ive had a 300A CB cut out at about 170A a few times now, so they can be way out of spec. Hope this helps.
Good demonstration of the capabilities of this dc -dc converter. However, you mentioned the term ‘buck’ a few times whereas you should have used the term ‘boast’. Buck decreases the output voltage compared to the input. Whereas boast increases it, as demonstrated in your video. en.wikipedia.org/wiki/Buck-boost_converter
Brilliant, can’t believe I haven’t found you before. Brilliant information brilliant test.
Glad you found it helpful. Cheers Tim
I have been trying for over a year and have had various technical guys look at the DC to DC charger..... no one got it installed in my travel trailer (carvan) working correctly. Your video solved the problem. The final missing piece is the grounding of the negative. This allowed the LC to reduce the amps by 50 %.
Finally, I can tell Renogy to close their file.... and watch your video.😊.
Guess the Aussies are smarter than all the Canadian tekkies.😅
Thanks. The clearest explanation I’ve seen about how a dc to dc charger works. I didn’t understand how a 40 amp dc to dc could need up to 60 amps
You're welcome! Yes I'm sure that is not well understood and I have often heard of fuses blowing because they have not allowed for the overheads (inefficiencies) of these converters through low voltage input due to cable losses.
I tested this only yesterday while away camping to see what the current draw was at 40A output charge rate and its 50 amps input from the car alternator. This is due to some inefficiencies but also the voltage drop over the cable run from the vehicle alternator/cranking battery to the charger in the van (about 10 meters of 10mm cable). The DCDC charger has to boost the voltage up from say nominally 12 volts input (possibly lower at that current) to 14.6 approx output (the correct bulk & absorption charging voltage for AGM and lithium batteries. So the input current will always be significantly higher than the rated output.
Bit of an update - I was on the road for about 7 weeks in July-August with quite unseasonally hot weather in Northern Australia with 3 weeks of over 35C everyday. We relied on this to maintain the batteries and this charger has done a great job - with one exception- the ignition sense has failed and have contacted Renogy but its a bit hard testing it while we are moving everyday or so. I told them I will look at it when I get home as it really doesn't inconvenience us at all.
Hi Tim, interesting video mate - did you get a solution or a response from Renogy on this? (ignition sense?) - Thanks Mate
I contacted Renogy when I got back sent a short video showing the problem and the sent me a replacement so can't fault that service.
I considered the DCC50S but after reading the specs very carefully, I understood that it would only output 25 amps from alternator and 25 from solar. The 50 amp rating looked to be a combination of the two inputs. Like you, I prefer a separate DC to DC charger and a separate solar charge controller rather than a combination unit. I ended up with the Renogy 40 amp DC to DC charger and an Epever 40 amp Triron controller. I'm really happy with the end result, too. I'm running 4S2P 125ah LiFePo4 with 100 amp BMS's and it is rock solid! Your explanation of the constant current charge using to Renogy DC to DC is spot-on as well. Good video. Thanks for putting it out for us to see.
Thanks for your feedback. I'm running a Renogy 30 Amp Epever solar controller in this new setup and very happy with the result. A friend recently had an issue with an "all in one" Projecta PM435 when it failed and that left them with no power at all including the fridge and no way to charge the batteries. Turned out to be a simple issue in the end but highlights the vulnerability with these one stop solutions.
Thanks so much for this, I was wondering if these units had buck/boost converters, now I know!
I have been charging with shore power via a server power supply for many months via the Renogy 40amp, and it's perfect, no issues at all and it's consistent and reliable. The PSU was 15 pounds from eBay. If people want to spend 10x that on a victron or a Noco then ok, but the PSU puts out 52amps at 13.2v the dc to dc max is 40amp and the whole thing works very well together. 480 to 510 watts well👍
I was surprised there is no delay when it see's 12v @ the D+. It starts pulling 50+ amps from start batteries. I put mine on a 3 way switch off/20/40, feeding 12v from ignition. gives options and time to start motor without compromising start bank. Why there is not at least a 5-10 sec delay is beyond me. Im on a boat so I need a bit more time to start up motor before this thing pull amps from start batteries. Nice video thanks !
Yes you would expect some delay. Thanks for the feedback. Cheers Tim
I’ve just bought one of these and I think I’ll put a switch on the current limiter wire so I can easily change to 40amps only when I really need to AND I think (would like) to connect it to my headlights so it only turns on when I have the headlights on.
So it’ll only work when there’s no more sun on the panels and if I need it thru the day, I’ll just put the lights on. Dunno if that’s a good idea or not? I do like the voltage drop relay but don’t know how to wire that up.
EDIT: my initial thoughts was not the best idea. In the end, I just connected it to a 12v source that isn’t active after the car is turned off as recommended, but also installed a switch to turn it on or off while the car is on as 99% of the time, I don’t need it. At first I thought it was a real hassle having to wire up that 12v wire, but I actually love it. And it works really good so far. 👍
I would be inclined to run it a 20A is you run it when the lights are on as you want to limit the load on the alternator as much as possible. Most alternators are not designed for a constant high load current as is the case with these chargers. I would only run it at 40A if the battery was dead flat and I needed it to recover quickly. I would only run it at 40A is I was driving at highway speed to keep the alternator from overheating.
@@timterry8714 yeah you’re right....after I posted my comment, I realised it’s probably a stupid thing to wire it to the lights.
Currently, I’ve just wired it as recommended to a 12v source thats only with the ignition on. I’m then going to wire in 2 switches, 1 to manually control it to 20 or 40 amps, and the other to turn it completely off.
I think during full sun days, which is most days, I won’t need it at all.
Yep, have mine on a 3way off/20/40, otherwise this thing pull 50+ amps from start batteries as soon as it see's 12v @ the D+ wire. no delay. I want time for motor to start, and warm up.
@@sailingsinequanoneuc5265 Is the 3 way option part of the charger or a separate switch one must install? Thanks
@@sr7486 its a separate switch you connect to the terminals. Normally you would have 2 switches. One is the ignition, the other is to go from 40 to 20 amp. If you use a 3 way switch for 20/40/off, you need a diode between center pin and D+
Boost mode, lower voltage in, higher voltage out. Buck, high voltage in, low voltage out. Thanks for the video. This is just what I'm looking for to avoid blowing up my alternator.
Yep the boost function works really well on this model - much better than the DCC50S which doesnt work in the alternator mode unless the voltage in is well above 13 volts to achieve a usable output.
Had a problem with mine, my first 40 amp renogy stop working on just a 400-mile trip, I did notice it was pulsating voltage that was going into my house batteries, they sent me a replacement, check that today and it is still sending a pulsating voltage. 20-amp renogy I had previously, failed after about a year, so I ordered another 20 amp renogy, and now that I've jumped up to the 40 amp renogy I'm using the 20 is a backup. The 20 never pulsated the voltage, does that sound right with the 40 amp
I havent seen that issue so cant comment unless its an equalisation function you are seeing which is for Lead Acid batteries and shouldnt be present for Lithium. Check battery type setup as per manual. Otherwise not aware of that issue.
I bought one of theses, the 20A Renogy DC-DC on board battery charger, model DCC1212-20. I placed a 30A breaker on the pos line from the starter battery to the device, as per the instructions. However, the breaker keeps flipping. I changed it out, but the new one keeps flipping. So this device is not charging my house battery because of this. I have a 150 amp alternator. Before I bought the device, I called Renogy and was told to buy the 20A device. Now, the Renogy customer service number hangs up after it plays the initial introduction message.
What do you recommend?
I would have thought you should have a bigger breaker than 30A as the charger can draw about 25 amps from the vehicle battery to output 20A. I would have a 40A breaker. I use a 70A for my 40A charger and 40A for a couple of 20A chargers I have installed. Does it trip instantly? If so thats indicating an issue - if it takes a few seconds it may be that the breaker is to small. Also as the input voltage drops below 12.5 volts the input current will increase to maintain output voltage (see video) the cable maybe a bit undersized causing voltage drop, higher current, breaker trips! Also some breakers have very poor accuracy unless they are properly designed very expensive DC low voltage breakers. I would try a much bigger breaker or better a ANL fuse.
@@timterry8714 Renogy said to use a 30A breaker, but the 30A manual reset breaker I bought, as it turns out, was opening at less than 30 amps. I replaced the breaker with a 30 amp automatic reset circuit breaker...everything is working ok now.
Renogy recommends fuses not breakers. Most breakers are rubbish, should be using anl or midi fuses with a dcdc charger
Why did you reduce it in half and not the full 40amp. By reducing and it's like you have the 20 version??? Or am I missing something here?
I run it at 20 amps as thats all I need most of the time and importantly to reduce load on the alternator. At 40amps out the alternator has to supply approx 55 amps input continuously and thats not good for it. I only run it at 40 to catchup when the battery is very depleted and I'm highway driving to keep the alternator cool under this continuous high load.
Just wanted to say thanks for this video. I've been looking all over the place for more detailed operation on this unit and you got the job done. Thanks!
Glad I could help. Cheers Tim
I submitted a Q to renogy via their support website : How many amps reach the leisure batteries when 1. Engine running (50amps available ) and 10 amps of Solar are also available 2. Engine not running and 40 amps of Solar is available. A1: DCDC charge controller will attempt to maximize the solar input first. It will take as much power as possible from the solar panel (up to 10 amps in this case) before supplementing it with power from the alternator. So, the leisure batteries will receive up to 10 amps from solar, and the remaining power required to charge the batteries up to their set voltage will come from the alternator (up to 40 amps) A2: If the engine is not running, and you have 40 amps of solar input, the DCDC charge controller will utilize the full 40 amps from the solar panel to charge the leisure batteries.
Hey Tim
Once again enjoying another another of your informative well explained clips.
Awaiting delivery of my caravan and have decided to organise my own battery/dcdc charger and solar setup rather than factory gear. Intrigued to hear your suggestions on what renogy products to install to support a 12volt compressor fridge (ThetfordT2175) with y given your learnings and experiences. Currently considering 200 amp lithium batter, this 40 amp charger, a separate solar regulator with 200 watts fixed solar and 200 watt solar blanket.
Any other suggestions welcomed cheers.
I recently installed a Bushman 190Ltr compressor fridge to replace the disaster Dometic 3 way fridge that came with my caravan. The 200A/h's of Lithium Batteries supported by 2 x 175 watt Renogy Flexible solar panels and a portable folding 300W panel have proven to be more than capable of supporting the Bushman (even without the portable panel being required most of the time). I also now run a Breville Coffee machine via a 2Kw inverter, occasionally the microwave and washing machine. If I had the space on the roof I probably would have opted for a 3rd 175w panel but at this stage it seems unnecessary in most situations. Having said that this years terrible weather has certainly tested the capacity to the limit - but so far so good. I also have the 40A Renogy solar controller which I covered off on another vid here elsewhere. I very happy with this setup and the 40A Renogy DCDC charger (95% of the time it is only ever run at 20A charge rate). So I think you've got it covered off prety well. Cheers Tim
best part of your video is youve done something nobody has done,used a seperate power source to charge another battery bank.I have 2 solar systems on my trailer and I could use the one not used but for lights to help out my other battery ban.
Thanks for the review. I am looking for this 40amp charger for my car. Will see how reliable they are.
Have installed quite a few and all working well to date.
Thank you, sir.
I'm setting up my rig with an inverter system for the first time. I was looking at this unit in particular to supply the correct charging voltage for two ≈120 ah marine batteries in a battery box I will fabricate soon.
Cheers, brother!
🍻
Glad I could help
Tim - A common problem folk have with these units is that folk fit 30amp breakers to 20amp units and they trip on start up - this is due to two phenomina - When the engine starter is engaged the engine battery voltage dips due to the extreem load, causing current to rise as you clearly showed, combined with the inductor & capacitors in the Renogy unit which cause demand to spike - The combination of both can exceed 30a momintarily - I use a 20a unit wired with 7AWG and a 40a Maxi Fuse and the unit has worked flawlessly
Mine did have a fault and after Renogy replaced it and I installed it hasnt missed a beat with no other changes.
@@timterry8714 I still think your marginal on that 30amp breaker especialy when your house battery is at near full and cold thick oil dips your engine battery on a colld morning start up - good luck
Hey there. Great Vid. I just bought one of these. Hooked it just as you have done - it is limiting the charging amps perfectley at 20 amps. Now how do i get the full 40 amps ? I took out the LC wire and amps don't change at all - still sits at 20 amps ? Am i missing something here ? any help would be great - i have contacted renology but havn't heard back from them yet.
Hi Andrew, I had a fault in one of these where it was ignoring the D+ input and working all the time regardless of whether +12 was on that terminal or not. I raised a job ticket with Renogy about this and after a few email back and forth and a short video demonstrating the problem they sent me a replacement - so you may have the same issue. It sounds like its clearly not seeing a change of state from the +12V input to the LC terminal. I fed mine from the +12V input terminal by the way. Cheers Tim
@@timterry8714 Hi thanks - I have fed mine from the 12voly input as well. I'll have to go back to Renogy ; what a hassle though !!
Thanks for a well presented test. May I ask what size alternator is in your vehicle? Would rather charge at 40A than 20A, if my 160A alternator has enough spare capacity.
Not sure but at least 100A. Its the constant load that's the issue. Being able to deliver Hi current for a short time is normal in a vehicle but its the continuous hi current load for hours thats the issue.
Looks like the problem with this charger is it will run your start battery flat. While
the 50amp you tested before prioritised the start battery
The start battery is protected by installing a VCR to isolate the charger after engine shutdown, or installing an ignition sense wire to D+ terminal. But this one does charge properly.
Beautiful explanation, you advise you to buy?
Yes, definitely but remember its a vehicle charger only does not have a solar input. I prefer to have separate chargers to provide redundancy. Dedicated solar controllers have lower overheads (lower internal power consumption) also thereby providing greater efficiency.
@@timterry8714 Thank you for your response, I really want to charge from the car generator just don't want solar power thank you so much brother 🙏
@@timterry8714 yes on my ctek I only use it for alternater charging because max amps are only 20 with solar or no solar so I wanted 20 from alternator and what ever I can get from seperate solar charger.
Hi, thanks for the info. Can I ask why you run it at half the 40Amps? I don’t understand. Thanks
That's the real question here is can it actually output it's rated 40A?
He probably ran it at half amps because as he turned voltage down the amp pull would have exceeded his power supply. Just a guess. I do wish you would have measured output voltage too.
Hi Oliver, I run it at 20 amps to decrease the load on the car alternator and I dont need the higher capacity at the moment as I only have a 100Ah battery. I purchased a 40 amp in thinking that I may increase the battery storage at sometime in the future and would the look at utilising the extra capacity. It seems to keep the battery fully charged even while running the 3 way fridge while driving.
I very recently decided to upgrade to 200A/h of lithium as its quite reasonably priced now and I will add a switch to the current limit input port so I can select either 20A or the full 40Amps if I need to really boost the battery after several days of no sun which I recently experienced. I will normally only run at 20A to minimise load on the alternator.
Yes C5turbo, it does output a full 40A and I demonstrated that in the video. It achieved full output all the way down to around 9.5 Volts at the input terminals which is very impressive. With the current limited it sat at approx 19.5A output over the voltage operating range specification.
I bought the charger but is the trigger (D+) wire just a regular flexible 18awg 12v wire?? Can I put an on/off switch in the line?
Just a light gauge wire and yes I have a switch in line to enable/disable the charger. I actually tied the D+ to the +12v input via a switch so it starts as soon as I connect it to the vehicle. The switch is actually a voltage controlled relay so it shuts down the charger at 12.8V.
yep, have mine on a 3 way, off/20/40.
Omg!!! I have been watching these videos for months to understand!! I finally understand ! Thank you so much ! I have a qustion can I hook it up to my started battiery ? Or dose it have to be from my alternator?
Glad it was helpful. The input to a DCDC charger is from the starter battery positive and a solid connection to the chassis (for the negative). Do not connect the negative to the battery negative. Cheers Tim.
Holy s you just convunce me to get 40amp dcdc charger .i was wonder wich ine to get that would work good .and man you showed me exactly what i wanted to know.thank you so much ..i was going to make a small generator out of weedwaker engine.might still do it but u helped me decide greatly....
Hi Tim glad that helped - this is what RUclips is great at I think! Cheers Tim
How hot it is while operating on full ?
Gets pretty warm but it has an internal fan and its designed to do it.
Very well put
Thanks
What is the reason for dropping the output in half to 20 Ams?
It gives you options. I have mine installed with a 3 way switch. off/20/40, this way you can pull only 20 if you are running the engine at low RPM's or if you just want to slowly charge the bank, or if you want to put less stress on the alternator. Without the switch, and set for 40 amps, the unit pulls about 50+ amps from your start battery as soon as it see's 12v at the D+ wire. There is little to no delay (should have been a 10 sec.. delay in my opinion, to get the motor running). I switch mine on at 20amps once the motor is well under way, then switch to 40amps once at cruising speed if needed. installed on a yanmar 15hp w 80 amp alternator. Cheers
I agree completely with the above comment - the alternator load is an issue unless the vehicle has had a high current or heavy duty alternator installed. I have only run mine at 40 amps once when my battery bank was totally depleted after I left my 3 way fridge on DC all night. I was traveling at highway speed 100kms/hr the entire time so the alternator was able to stay cool - definitely would not run it at 40 amps if I was driving in the city at low speed and stop/start or in high summer temps.
I always thought that Renogy was squarely aimed at the American RV market so caravans and voltage drop probably isn’t something they care about so much.
The 20, 40 and 60 amp DCDC chargers do work properly the 50A on the other hand has a design flaw which they may have sorted out by now.
good on you mate
Thanks mate,
I had one of these things I found the fans to be very low quality and they started making a noise after about a year it just kept getting worse and worse
Buy some new 40mm fans from ebay, cheap easy replacement.
I havent heard the fans running and making any excessive noise as yet. Not sure that would be an issue really as this charger is only running when we are driving and as its in a caravan no one is in the van when its being towed.
R these ok for smart alternators or just dumb ones?
These are designed for both smart and dumb alternators. They work down to about 10 volts input (smart alternators run around 12.5 volts). You need to install an ignition sense wire to shut it down when the vehicles is stopped and that is connected to the D terminal on the charger.
Many thanks, tim
That pack got a 100amp BMS?
Yep
thank you very much 👍👍👍👍👍
Welcome!
Dont forget to hook up the trigger wire or your starting battery will be dishcharged it wont know that you have shut the engine off
I'm going to fit a low voltage dropout relay.
@@timterry8714 Isn't that what the trigger wire does inside the dc-to-dc charger
@@timterry8714 The only downside on that dc-to-dc charger That I can think of is It is Drawing current as soon as you start your vehicle . If you could put in a programmable time delay relay You could program it so it wouldn't start charging Until you know your starting battery is charged up . I installed one on my side by side . For some reason the manufacturer thought it was a good idea That the radio should turn off after 1 minute When the ignition key was turned off . Not so great if you want to listen to the radio When you are parked The one I bought you can set It up for all kinds of programs . You can set it for whether the ignition is cycled off or when it's cycled on it starts Counting . I have it set for an half hour Then it turns off the radio I can program it for however many hours I Want it to run . If it turns off all's I have to do is cycle the ignition key and give it a 12-volt trigger It comes with a built-in 10 amp relay . It's a neat little device and I think it was only $20
@@bucket1249 What does it matter ????Who cares if its drawing current ( I presume you mean Main battery charging current) as engine is running.......The reason people want me to instal these devices is for exactly that reason..........Your Main battery is still going to come up to charge , probably long before the Aux battery will because the starting discharge generally bugger all re its capacity....
@@grahamhastie896 I'm just thinking about people who have puny alternators in little cars and trucks it it'll charge but it's going to take a toll on your alternators after a while
Do not buy this product! The warranty and customer support is the worse I have ever seen. Did not work from day one. Thank God for Amazon, they helped, but Renogy did nothing. Very poor customer service.
Yes they have a very chequered history in customer service!
Hello
I recently bought and installed a renogy dc-dc 40A according to the instructions. Why does the 60amp fuse blow? after 10-15 minutes
The cables are 35mm2
The 40A dcdc charger draws about 55 amps or so due to conversion inefficiencies. So depends how good your fuses are. You should have a 100A fuse.
@@timterry8714 I installed automatic fuses from Amazon
Do you think I should put 100amps? I'm afraid that something will burn
Thank you for your quick response👍
You should nearly double the expected maximum for a fuse.
@@jaca2107when u say automatic fuse,do u mean a resettable circuit breaker? If so, then yeah, go to a 80A-100A circuit breaker, especially if under bonnet as the extra engine heat can cause these CB’s to trigger earlier than specified and the cheaper versions can also be out of spec & trigger under much lower current usage than specified. Ive had a 300A CB cut out at about 170A a few times now, so they can be way out of spec. Hope this helps.
@@evil17 This junk destroyed and burned my ECU
Good demonstration of the capabilities of this dc -dc converter. However, you mentioned the term ‘buck’ a few times whereas you should have used the term ‘boast’. Buck decreases the output voltage compared to the input. Whereas boast increases it, as demonstrated in your video. en.wikipedia.org/wiki/Buck-boost_converter
You made a mistake as well. It's a "boost" converter, not a "boast". =)
Ha ha, too true. I don’t want to boast that it’s a boost converter. The difference one letter makes!
Your right Steve I got that wrong it is a boost not a "boast" or buck, cheers.
@@timterry8714 hey Tim absolute novice here. Thanks for your explanation. Any chance of advice through messenger or a phone call. Thanks Paul.
Yep I keep getting buck and boost back the front.