Mate, best look at van power and dc-dc's I've seen. Based on checked facts, rather than someone's opinions. Good stuff. I've had dc-dc's for a few years now, even in my boat. Definitely improve performance and get around a lot of issues. The wiring in the Jayco is puny. Well worth wiring your veh. with 6b&s to an anderson plug at the towbar, then run 6 b&s from there (with an anderson) into your van, replacing the power wires on your 12 pin. If you run it to your fridge and charger in the van you'll see another big jump in performance. Also, if you have a 3 way fridge, run the heavy cable to it as well. You'll be amazed how much better a 3 way runs on 12v with heavy cable from the alternator. Voltage drop is really the big issue with 3 ways on 12v. Anyways, subbed and keen to see your stuff. Keep 'em coming, cheers PP
Thanks mate, glad you found it useful! Yeah I reckon the stock wiring isn't really designed for what we put into it these days. I already have thick wiring on the car but could do with upgrading the van wiring. Cheers!
Very useful Australian video covering DC to DC Charger basics. I've been looking for this information for a couple of years and you have delivered. Thanks.
Great to hear Al! Glad to know it was useful. Let me know if there's anything else related you might be interested in and I'll see if I can include it in a future video!
Hi Greg. Great video. I have similar problem as you , which is not even getting close to the rated current. Redarcs answer was 'too much voltage drop, cable size it too small', they said you need a input voltage of about 13 volts at the Redarc to achieve the rated output (in your case 25 amps) which makes the Redarc fairly close to useless unless you spend more on cable than you do on the Redarc. Even with under size cable I admit that the battery will still get fully charged as when the current comes down, the performance will increase. Your 2 1/2 flat AGM's would have easily consumed 25 amps if it was available to them. I assume the right hand voltage meter was the voltage coming into the redarc, not the battery voltage.
Hi Hamish, Glad you found it helpful! Are you saying you're having this problem WITH the Redarc DC-DC charger installed, or on the standard setup WITHOUT the charger? I had the issue of low voltage at the batteries on my standard setup before installing the charger, and yes thicker cable might have alleviated that a bit, but it would never solve the problem completely because the input voltage is just too low. After I installed the Redarc charger I had no issues at all getting decent charging rates with my standard wiring because the charger's able to apply more load to the alternator than a battery does, and thus the charger pulls far more current through than the battery on its own could. Yes the right hand voltage meter was measuring the voltage coming into the charger, and as current increased this dropped (due to cable voltage drop). However that is a pretty irrelevant reading, because what really matters is what the Redarc charger does with whatever voltage and current it gets. As you saw at about 5:12, with the Redarc charger I was getting about 14A flowing INTO the batteries (bottom right read-out) with a voltage of about 13V (top left read-out). With standard wiring. You'd struggle to get that reliably on a standard setup even with thick wiring. Let me know if I've misunderstood something. Cheers, Greg
@@TheMusingGreg Hi Greg. yes I was having the issue with the charger, but mine is a BCDC40 which just makes the small cable size more of a problem. You are also having the issue, although it may not be as evident. When you have 2 x 1/2 flat agm batteries, the BCDC will be in Boost mode (constant current) At this time you should be getting 25 amps into the batteries, with the voltage rising until it gets to about 14.5 v , then the charger will switch to absorption (constant voltage) Redarc appear to have built in a self presentation delimiting factor to roll back the output when the input voltages gets below 12.5 volts. People could say 'well use the recommended size cable them' which is fine, but it somewhat defeats the purpose of a DC-DC charger. I don't believe Redarc are alone in their omission of the devices true performance.
Hi mate, Yes if you're trying to draw 40A through factory cables that were probably only designed for 10-15A, you're likely to get reduced performance. Mine would have been down probably for a similar reason, as I was only getting about 18A into my batteries when in Boost mode. The unit's 25A rating would I guess be a bit like what I've found with solar blankets - it's what it's capable of producing in ideal environments, but there are many factors that can limit what they actually produce. But 18A through my factory cables was still a huge improvement over what ended up being only a couple of amps once the van battery was about 3/4 full. I get how you've come to your statement that thicker cables somewhat defeats the purpose of a DCDC - if you've got to put in thicker cables anyway, wouldn't that remove the need for a DCDC? However thicker cables are not *necessary* for a DCDC charger, they would just mean it would charge faster. But even with the original cables, a DCDC will draw a lot more current than your batteries would get without the DCDC, and without the DCDC you'd only get about 3/4 of a charge. If you put thicker cables in, you're still not going to get the same amount of charging current going into the batteries because you might have 14.4V at the alternator but there has to be some voltage drop through several metres of even quite thick wiring, whereas with a DCDC you've got your 14.4V right there at the batteries. Plus of course it can do the Boost, Absorption and Float which an alternator can't do. The DCDC charger can put a much heavier electrical load on the system than the battery on its own can draw, which means it will always be able to suck through more power than the battery, be that through thick or thin cables.
I have just managed to get a hold of a REDARC BCDC 1250 DC-DC battery charger for my 4WD. I already have a REDARC isolator in the 4WD when I got it but wanted to add the charger to the system. The 4WD already has a dual battery system in it but I would like to add a deep cycle battery in the rear. The question I need to ask is would mounting the charger at the front of the 4WD be ok with the dual battery system and also the deep cycle battery I want to install in the rear of the 4WD ?
So to confirm, the existing dual battery system will be unchanged, while the BCDC is going to be mounted at the front of the vehicle and its output connect to the new battery at the rear? And that new rear battery isn't going to be connected to the original two in any way (other than sharing an earth)? If that's the case I can't see a problem with it, just make sure the wiring to the rear battery is thick enough as 50A is a lot of current. I'm not sure what purpose the 3rd battery serves but I assume you've got your reasons. I just wasn't sure if your new battery was going to be run in parallel with one of the two existing batteries, in which case the answer is a bit more complicated.
Pls help. I have this charger in a duel battery system with an Anderson plug out near the tow bar. CAN I just plug solar into that Anderson plug and leep my battery topped up? If so do i need the solar regulated?
It depends if that Anderson plug is connected 1) straight to one of the batteries, or 2) to the solar input of the Redarc charger, or 3) to the output of the Redarc charger. Anderson plugs near the tow bar are usually designed as a 12v OUTPUT to a caravan, so I doubt it's option 2 (but if it is then yes you could connect a solar panel straight into that connector with no regulator). If it's option 1, yes you could connect a solar panel but you would definitely need to run it through a solar regulator to bring the voltage down, otherwise you'll fry your battery and vehicle electrics. If it's option 3, then no you wouldn't be able to connect a solar panel to it, however there would probably be a separate solar input to the Redarc unit somewhere which you need to locate, and then you can plug a panel straight into that. If you have a multimeter, switch it to Volts and measure the battery voltage on each battery with the engine turned off. Then measure the voltage onto the two terminals of the Anderson plug and see if it matches either of the first two readings. If it does, chances are the Anderson plug is connected directly to that battery in which case it's option 1. That's about the best I can do from what you've told me but let me know if you have any more questions and I'll do my best to help
Glad it was helpful mate! It completely depends on how you've got it wired up, but not usually. This charger is really designed to keep a second battery properly charged and conditioned independently of the main battery, as the main vehicle battery should always be being kept charged by the alternator. If the main vehicle battery needed extra charge, it would be more efficient for that charge to come straight from the alternator, rather than through the charger and then back to the battery.
@@TheMusingGreg ah yeah I didn’t think it would. I was thinking along the lines of a camper van that could be parked up for a month not getting used. Cheers mate.
This unit only has two power inputs: alternator and solar (the Redarc Manager30 has a 240v input too). The alternator is obviously only going to run while the vehicle is running so there's nothing to be gained there as I described; however if your camper has a solar panel and it's stored outside you might end up with spare power from that. If so, you could configure your system so once the secondary battery is fully charged it switches the main battery in parallel to get topped up. Check with Redarc what would be the best tool for that, but they do have battery isolators which I reckon would be what's required. Good luck!
Hi Greg, really enjoyed / appreciated this video. Technically it was good information. Question for you though. Do you think there would be value in gains by increasing your supply cables. They look like they are around 10mm2 . I'm not sure what the redarc cable sizes are. Increasing too 16mm weld flex might further help with the voltage drop and mean the redarc and alternator has a little less work to do? What do you think?
Hi Phil, Thanks for the comment.Yep I think there's absolutely value in that, but so far I'm just using what's already on the car and van. The vehicle cabling is very heavy but the stuff on the van is quite a bit lighter in parts. The Redarc stuff is very thick, probably 4x what Jayco used when they built the van, but then they probably weren't expecting 2 batteries. That said, that would only go a little way to addressing the problem - with the diode bypassed you might be lucky enough to get 13.5V at the batteries with really thick wiring, but even then you need the voltage above 14V in order to get the batteries charged up to 13.8V in a reasonable timeframe. The BCDC is actually capable of outputting up to 15.3V if necessary, which is more than the alternator would provide, so thicker cables would only reduce how bad the problem is with direct charging, but it won't fix it. For what it's worth, before I had the DC-DC charger installed, I had a switch which bypassed the diode which I would leave on while we were travelling. It certainly helped, but obviously still nothing like the results from the BCDC. Cheers, Greg
@@TheMusingGreg I have not done any research yet. Just collecting ideas. I think the more the voltage drop to the redarc means the higher/ harder it has to work. It sort of looked like it is bumping up the voltage from the alternator. Hence suggestion for increased cables. PS I'm waiting for Hilux to arrive sometime next year 😢 as lithium is sensitive to heat, am considering putting battery behind rear cab seat, and will run fridge and winch and fee accessories of that. Then use switch later to swap between cabin battery and a caravan one . Then I'll pull the books and look at the voltage drop issue properly. Thanks again. Great vid. A lot of work there.
No worries Phil, thanks, I appreciate it. That sounds like a reasonable plan. Yep within reason, the thicker the wiring, the less losses you'll have along the way, which over time will probably pay off as it will reduce the workload on the BCDC to a point. Once you've worked out the likely total current you can select a suitable thickness cable. Good luck!
No. Lithium batteries and AGM batteries have different charging profiles. While this charger can be configured to charge either type of battery, it only has one charging output, so it can only do one type of battery at a time.
@@TheMusingGreg I'm working on a relate issue. I have 240A worth of lithium batteries in my camper trailer as well as an extra agm battery under the bonnet for the vehicle accessories/winch. I already have a redarc VSR to charge the winch battery. I was told that I could run cables from my main starter battery to the rear bumper with an anderson plug to connect to the trailer. Add the BCDC charger in the trailer and let it charge the lithium house batteries from the main start battery. Is that correct? I guess what I is; can I charge the winch battery from the start battery via VSR (both batteries are exactly the same) AND power BCDC charger to the lithium trailer batteries?? Great video and thanks!
@@ailo4x4 Hi mate, if I understand correctly, you're using the alternator on your vehicle to firstly charge the start battery. Once its voltage has come up enough, the VSR switches to the aux battery and your alternator then charges up the aux battery. Is that correct? If so that setup is fine. I think what you're suggesting should work, although it would be better to connect the BCDC to the Aux battery rather than the start battery. It's never good practice to run things from the start battery especially if you've got an aux battery available, it's a recipe for something going wrong and flattening your starting battery and then you're stuck. The more current the BCDC draws, the lower the supply voltage goes, and in your specific case this could cause one of two issues: 1) The BCDC will be drawing a lot of current to charge the lithium, and it might keep the voltage low enough so the VSR stays switched onto the start battery. This would mean your Aux battery never gets charged until the lithiums are close to full. 2) Even if 1) doesn't happen, as soon as the VSR switches and your alternator starts charging the Aux battery, the BCDC will immediately start flattening your start battery until the VSR detects the Start battery's getting low and switches back to top up your start battery, and the cycle repeats itself all day long with the VSR switching back and forth. This fluctuation of the supply voltage to your vehicle could cause some issues, and the BCDC isn't going to charge as effectively as it'll be trying to suck 20-50A from just a battery rather than a more powerful alternator. But if you wire your Anderson plug to the Aux battery, your start battery will get its all-important top-up charge as soon as you start your engine. Only after that will the VSR switch across to charge the Aux battery, and this jump in voltage should trigger the BCDC to turn on and start charging your Lithiums at the same time. Your start battery condition is always maintained and prioritised, as it should be, and it won't lose much power just running the vehicle's electronics compared to powering the BCDC. Hope this helps! Greg
@@TheMusingGreg Thanks Greg, you are the man! I would have thought this would be an issue that would have long been settled with the vast numbers of Aussie camper trailers being pulled by trucks with big winches. I contacted Redarc some time ago about it and their solution was to use two 1225D BCDC chargers. One for the under the bonnet for the winch AGM and one in the camper trailer for the lithiums. I get it but that is a LOT of money. I always thought there has to be better way. I'm an American expat living in the UK with a old school Defender and, believe it or not, an MDC Cruizer Highside forward fold camper trailer. My English wife and I are planning on shipping the whole rig to Cape Town in 2026 and spend a year doing southern Africa. Right now I just charge the trailer batteries up before I go and use solar panels to keep it going. But I really need to add power from the truck to charge as we drive. My under bonnet AGM is used mostly to power the accessories in the truck like the air compressor, small truck fridge, etc. and if really needed, the winch. So having it in the middle of the system shouldn't be too much load. Any further thoughts greatly appreciated! Cheers, pal!
@@ailo4x4 More than happy to help! Look, the AGM having its own DC-DC charger would of course be the ideal, I was assuming you had ruled that out. Two DC-DC converters means the AGM, the Lithiums and your start battery are always getting charged simultaenously but being monitored independently of each other which is the best situation. It has to be said that the Lithiums / DC-DC will draw a lot of current, so whichever battery they're connected to, the VSR will stay switched onto that battery most of the time - which means the other battery won't be getting charged most of the time. And that's not actually ideal for either battery unless there's only a light load on the other battery and it only needs a periodic top-up charge. What I suggested would probably work fine most of the time, but if you're driving at night with the spotlights on or other heavy electrical load conditions, the VSR will probably stay switched across to the start battery most of the time which would mean your lithiums wouldn't get charged if the DC-DC's connected to the AGM side of the VSR. The alternative is what you suggested, which would mean it's the AGM which wouldn't be getting charged most of the time. It probably comes down to how much load is on each battery. If it's only a few amps most of the time, the VSR would probably only need to tick over to charge it a few times a day while you're driving, but if either is heavily loaded, the VSR could end up switching back and forth as I mentioned. If you're only going to have one DC-DC charger, I still think the method I suggested is the better of the two options, so long as the VSR is configured to switch back to the start battery when it gets low. Just be aware there is a risk it'll stay there for a while and your lithiums won't get a charge. However I'll be honest with you: if I was planning on doing a trip as serious as what you've got in mind, I would bite the bullet and get a second DC-DC charger. If you want to save on cost, you could consider one of the Core units which aren't dustproof or waterproof and install it inside the camper rather than outside and save a few hundred. But if it's going to be responsible for delivering your power in rugged environments, I would be inclined to get the Classic unless you really can't stretch the budget beyond a Core. The extra cost would in my mind be worth it for the peace of mind and lower chance of a failure. Good luck whichever way you go!
Yeah that's a fair comment in 2024. It wasn't an issue for me when I reviewed it in 2022 but things have moved on. I'd expect they'll probably include that when they update this model.
Mate, best look at van power and dc-dc's I've seen. Based on checked facts, rather than someone's opinions. Good stuff. I've had dc-dc's for a few years now, even in my boat. Definitely improve performance and get around a lot of issues. The wiring in the Jayco is puny. Well worth wiring your veh. with 6b&s to an anderson plug at the towbar, then run 6 b&s from there (with an anderson) into your van, replacing the power wires on your 12 pin. If you run it to your fridge and charger in the van you'll see another big jump in performance. Also, if you have a 3 way fridge, run the heavy cable to it as well. You'll be amazed how much better a 3 way runs on 12v with heavy cable from the alternator. Voltage drop is really the big issue with 3 ways on 12v.
Anyways, subbed and keen to see your stuff. Keep 'em coming, cheers PP
Thanks mate, glad you found it useful! Yeah I reckon the stock wiring isn't really designed for what we put into it these days. I already have thick wiring on the car but could do with upgrading the van wiring. Cheers!
I'm looking at one for the boat. Great you did the unboxing at the end!
Glad it was helpful! It continued to work very well the whole time we owned the van!
Very useful Australian video covering DC to DC Charger basics. I've been looking for this information for a couple of years and you have delivered. Thanks.
Great to hear Al! Glad to know it was useful. Let me know if there's anything else related you might be interested in and I'll see if I can include it in a future video!
The musing greg does it again! Nice work mate.
Cheers mate! 👍
Fantastic episode- love our Redarc BCDC
Great thanks for the feedback Charlotte! Glad you've had a great experience too!
Great video, thank you. I learned a lot. Appreciate your work and experience. Keep on keepin on 🤙
Thanks very much, I'm glad to know you found it helpful!
Hi Greg. Great video. I have similar problem as you , which is not even getting close to the rated current. Redarcs answer was 'too much voltage drop, cable size it too small', they said you need a input voltage of about 13 volts at the Redarc to achieve the rated output (in your case 25 amps) which makes the Redarc fairly close to useless unless you spend more on cable than you do on the Redarc. Even with under size cable I admit that the battery will still get fully charged as when the current comes down, the performance will increase. Your 2 1/2 flat AGM's would have easily consumed 25 amps if it was available to them. I assume the right hand voltage meter was the voltage coming into the redarc, not the battery voltage.
Hi Hamish,
Glad you found it helpful! Are you saying you're having this problem WITH the Redarc DC-DC charger installed, or on the standard setup WITHOUT the charger?
I had the issue of low voltage at the batteries on my standard setup before installing the charger, and yes thicker cable might have alleviated that a bit, but it would never solve the problem completely because the input voltage is just too low. After I installed the Redarc charger I had no issues at all getting decent charging rates with my standard wiring because the charger's able to apply more load to the alternator than a battery does, and thus the charger pulls far more current through than the battery on its own could.
Yes the right hand voltage meter was measuring the voltage coming into the charger, and as current increased this dropped (due to cable voltage drop). However that is a pretty irrelevant reading, because what really matters is what the Redarc charger does with whatever voltage and current it gets. As you saw at about 5:12, with the Redarc charger I was getting about 14A flowing INTO the batteries (bottom right read-out) with a voltage of about 13V (top left read-out). With standard wiring. You'd struggle to get that reliably on a standard setup even with thick wiring.
Let me know if I've misunderstood something.
Cheers,
Greg
@@TheMusingGreg Hi Greg. yes I was having the issue with the charger, but mine is a BCDC40 which just makes the small cable size more of a problem. You are also having the issue, although it may not be as evident. When you have 2 x 1/2 flat agm batteries, the BCDC will be in Boost mode (constant current) At this time you should be getting 25 amps into the batteries, with the voltage rising until it gets to about 14.5 v , then the charger will switch to absorption (constant voltage) Redarc appear to have built in a self presentation delimiting factor to roll back the output when the input voltages gets below 12.5 volts. People could say 'well use the recommended size cable them' which is fine, but it somewhat defeats the purpose of a DC-DC charger. I don't believe Redarc are alone in their omission of the devices true performance.
Hi mate,
Yes if you're trying to draw 40A through factory cables that were probably only designed for 10-15A, you're likely to get reduced performance. Mine would have been down probably for a similar reason, as I was only getting about 18A into my batteries when in Boost mode. The unit's 25A rating would I guess be a bit like what I've found with solar blankets - it's what it's capable of producing in ideal environments, but there are many factors that can limit what they actually produce. But 18A through my factory cables was still a huge improvement over what ended up being only a couple of amps once the van battery was about 3/4 full.
I get how you've come to your statement that thicker cables somewhat defeats the purpose of a DCDC - if you've got to put in thicker cables anyway, wouldn't that remove the need for a DCDC? However thicker cables are not *necessary* for a DCDC charger, they would just mean it would charge faster. But even with the original cables, a DCDC will draw a lot more current than your batteries would get without the DCDC, and without the DCDC you'd only get about 3/4 of a charge. If you put thicker cables in, you're still not going to get the same amount of charging current going into the batteries because you might have 14.4V at the alternator but there has to be some voltage drop through several metres of even quite thick wiring, whereas with a DCDC you've got your 14.4V right there at the batteries. Plus of course it can do the Boost, Absorption and Float which an alternator can't do.
The DCDC charger can put a much heavier electrical load on the system than the battery on its own can draw, which means it will always be able to suck through more power than the battery, be that through thick or thin cables.
I got one given to me, yet to install
Well done it's a good product! Post back with results once you've installed it!
I have just managed to get a hold of a REDARC BCDC 1250 DC-DC battery charger for my 4WD. I already have a REDARC isolator in the 4WD when I got it but wanted to add the charger to the system. The 4WD already has a dual battery system in it but I would like to add a deep cycle battery in the rear. The question I need to ask is would mounting the charger at the front of the 4WD be ok with the dual battery system and also the deep cycle battery I want to install in the rear of the 4WD ?
So to confirm, the existing dual battery system will be unchanged, while the BCDC is going to be mounted at the front of the vehicle and its output connect to the new battery at the rear? And that new rear battery isn't going to be connected to the original two in any way (other than sharing an earth)? If that's the case I can't see a problem with it, just make sure the wiring to the rear battery is thick enough as 50A is a lot of current. I'm not sure what purpose the 3rd battery serves but I assume you've got your reasons.
I just wasn't sure if your new battery was going to be run in parallel with one of the two existing batteries, in which case the answer is a bit more complicated.
Pls help. I have this charger in a duel battery system with an Anderson plug out near the tow bar. CAN I just plug solar into that Anderson plug and leep my battery topped up? If so do i need the solar regulated?
It depends if that Anderson plug is connected 1) straight to one of the batteries, or 2) to the solar input of the Redarc charger, or 3) to the output of the Redarc charger.
Anderson plugs near the tow bar are usually designed as a 12v OUTPUT to a caravan, so I doubt it's option 2 (but if it is then yes you could connect a solar panel straight into that connector with no regulator).
If it's option 1, yes you could connect a solar panel but you would definitely need to run it through a solar regulator to bring the voltage down, otherwise you'll fry your battery and vehicle electrics.
If it's option 3, then no you wouldn't be able to connect a solar panel to it, however there would probably be a separate solar input to the Redarc unit somewhere which you need to locate, and then you can plug a panel straight into that.
If you have a multimeter, switch it to Volts and measure the battery voltage on each battery with the engine turned off. Then measure the voltage onto the two terminals of the Anderson plug and see if it matches either of the first two readings. If it does, chances are the Anderson plug is connected directly to that battery in which case it's option 1.
That's about the best I can do from what you've told me but let me know if you have any more questions and I'll do my best to help
Greg, I enjoy your content.
Do you need a Diode when using the DC-DC ?
Definitely not! The diode goes! That gets rid of the 0.6V drop which just made a bad situation worse.
Great video. Will the unit send extra power back to the main vehicle battery once the secondary battery is full?
Glad it was helpful mate! It completely depends on how you've got it wired up, but not usually. This charger is really designed to keep a second battery properly charged and conditioned independently of the main battery, as the main vehicle battery should always be being kept charged by the alternator. If the main vehicle battery needed extra charge, it would be more efficient for that charge to come straight from the alternator, rather than through the charger and then back to the battery.
@@TheMusingGreg ah yeah I didn’t think it would. I was thinking along the lines of a camper van that could be parked up for a month not getting used. Cheers mate.
This unit only has two power inputs: alternator and solar (the Redarc Manager30 has a 240v input too). The alternator is obviously only going to run while the vehicle is running so there's nothing to be gained there as I described; however if your camper has a solar panel and it's stored outside you might end up with spare power from that. If so, you could configure your system so once the secondary battery is fully charged it switches the main battery in parallel to get topped up. Check with Redarc what would be the best tool for that, but they do have battery isolators which I reckon would be what's required.
Good luck!
Hi Greg, really enjoyed / appreciated this video. Technically it was good information. Question for you though. Do you think there would be value in gains by increasing your supply cables. They look like they are around 10mm2 . I'm not sure what the redarc cable sizes are. Increasing too 16mm weld flex might further help with the voltage drop and mean the redarc and alternator has a little less work to do? What do you think?
Hi Phil,
Thanks for the comment.Yep I think there's absolutely value in that, but so far I'm just using what's already on the car and van. The vehicle cabling is very heavy but the stuff on the van is quite a bit lighter in parts. The Redarc stuff is very thick, probably 4x what Jayco used when they built the van, but then they probably weren't expecting 2 batteries. That said, that would only go a little way to addressing the problem - with the diode bypassed you might be lucky enough to get 13.5V at the batteries with really thick wiring, but even then you need the voltage above 14V in order to get the batteries charged up to 13.8V in a reasonable timeframe. The BCDC is actually capable of outputting up to 15.3V if necessary, which is more than the alternator would provide, so thicker cables would only reduce how bad the problem is with direct charging, but it won't fix it.
For what it's worth, before I had the DC-DC charger installed, I had a switch which bypassed the diode which I would leave on while we were travelling. It certainly helped, but obviously still nothing like the results from the BCDC.
Cheers,
Greg
@@TheMusingGreg I have not done any research yet. Just collecting ideas. I think the more the voltage drop to the redarc means the higher/ harder it has to work. It sort of looked like it is bumping up the voltage from the alternator. Hence suggestion for increased cables. PS I'm waiting for Hilux to arrive sometime next year 😢 as lithium is sensitive to heat, am considering putting battery behind rear cab seat, and will run fridge and winch and fee accessories of that. Then use switch later to swap between cabin battery and a caravan one . Then I'll pull the books and look at the voltage drop issue properly. Thanks again. Great vid. A lot of work there.
No worries Phil, thanks, I appreciate it.
That sounds like a reasonable plan. Yep within reason, the thicker the wiring, the less losses you'll have along the way, which over time will probably pay off as it will reduce the workload on the BCDC to a point. Once you've worked out the likely total current you can select a suitable thickness cable.
Good luck!
I have a second battery under the bonnet which is a AGM and a 200amp lithium in my van can It charge both AGM and the Lithium at the same time
No. Lithium batteries and AGM batteries have different charging profiles. While this charger can be configured to charge either type of battery, it only has one charging output, so it can only do one type of battery at a time.
@@TheMusingGreg I'm working on a relate issue. I have 240A worth of lithium batteries in my camper trailer as well as an extra agm battery under the bonnet for the vehicle accessories/winch. I already have a redarc VSR to charge the winch battery. I was told that I could run cables from my main starter battery to the rear bumper with an anderson plug to connect to the trailer. Add the BCDC charger in the trailer and let it charge the lithium house batteries from the main start battery. Is that correct? I guess what I is; can I charge the winch battery from the start battery via VSR (both batteries are exactly the same) AND power BCDC charger to the lithium trailer batteries?? Great video and thanks!
@@ailo4x4 Hi mate, if I understand correctly, you're using the alternator on your vehicle to firstly charge the start battery. Once its voltage has come up enough, the VSR switches to the aux battery and your alternator then charges up the aux battery. Is that correct? If so that setup is fine.
I think what you're suggesting should work, although it would be better to connect the BCDC to the Aux battery rather than the start battery. It's never good practice to run things from the start battery especially if you've got an aux battery available, it's a recipe for something going wrong and flattening your starting battery and then you're stuck.
The more current the BCDC draws, the lower the supply voltage goes, and in your specific case this could cause one of two issues:
1) The BCDC will be drawing a lot of current to charge the lithium, and it might keep the voltage low enough so the VSR stays switched onto the start battery. This would mean your Aux battery never gets charged until the lithiums are close to full.
2) Even if 1) doesn't happen, as soon as the VSR switches and your alternator starts charging the Aux battery, the BCDC will immediately start flattening your start battery until the VSR detects the Start battery's getting low and switches back to top up your start battery, and the cycle repeats itself all day long with the VSR switching back and forth. This fluctuation of the supply voltage to your vehicle could cause some issues, and the BCDC isn't going to charge as effectively as it'll be trying to suck 20-50A from just a battery rather than a more powerful alternator.
But if you wire your Anderson plug to the Aux battery, your start battery will get its all-important top-up charge as soon as you start your engine. Only after that will the VSR switch across to charge the Aux battery, and this jump in voltage should trigger the BCDC to turn on and start charging your Lithiums at the same time. Your start battery condition is always maintained and prioritised, as it should be, and it won't lose much power just running the vehicle's electronics compared to powering the BCDC.
Hope this helps!
Greg
@@TheMusingGreg Thanks Greg, you are the man! I would have thought this would be an issue that would have long been settled with the vast numbers of Aussie camper trailers being pulled by trucks with big winches. I contacted Redarc some time ago about it and their solution was to use two 1225D BCDC chargers. One for the under the bonnet for the winch AGM and one in the camper trailer for the lithiums. I get it but that is a LOT of money. I always thought there has to be better way. I'm an American expat living in the UK with a old school Defender and, believe it or not, an MDC Cruizer Highside forward fold camper trailer. My English wife and I are planning on shipping the whole rig to Cape Town in 2026 and spend a year doing southern Africa. Right now I just charge the trailer batteries up before I go and use solar panels to keep it going. But I really need to add power from the truck to charge as we drive. My under bonnet AGM is used mostly to power the accessories in the truck like the air compressor, small truck fridge, etc. and if really needed, the winch. So having it in the middle of the system shouldn't be too much load. Any further thoughts greatly appreciated! Cheers, pal!
@@ailo4x4 More than happy to help! Look, the AGM having its own DC-DC charger would of course be the ideal, I was assuming you had ruled that out. Two DC-DC converters means the AGM, the Lithiums and your start battery are always getting charged simultaenously but being monitored independently of each other which is the best situation. It has to be said that the Lithiums / DC-DC will draw a lot of current, so whichever battery they're connected to, the VSR will stay switched onto that battery most of the time - which means the other battery won't be getting charged most of the time. And that's not actually ideal for either battery unless there's only a light load on the other battery and it only needs a periodic top-up charge. What I suggested would probably work fine most of the time, but if you're driving at night with the spotlights on or other heavy electrical load conditions, the VSR will probably stay switched across to the start battery most of the time which would mean your lithiums wouldn't get charged if the DC-DC's connected to the AGM side of the VSR. The alternative is what you suggested, which would mean it's the AGM which wouldn't be getting charged most of the time.
It probably comes down to how much load is on each battery. If it's only a few amps most of the time, the VSR would probably only need to tick over to charge it a few times a day while you're driving, but if either is heavily loaded, the VSR could end up switching back and forth as I mentioned.
If you're only going to have one DC-DC charger, I still think the method I suggested is the better of the two options, so long as the VSR is configured to switch back to the start battery when it gets low. Just be aware there is a risk it'll stay there for a while and your lithiums won't get a charge.
However I'll be honest with you: if I was planning on doing a trip as serious as what you've got in mind, I would bite the bullet and get a second DC-DC charger. If you want to save on cost, you could consider one of the Core units which aren't dustproof or waterproof and install it inside the camper rather than outside and save a few hundred. But if it's going to be responsible for delivering your power in rugged environments, I would be inclined to get the Classic unless you really can't stretch the budget beyond a Core. The extra cost would in my mind be worth it for the peace of mind and lower chance of a failure.
Good luck whichever way you go!
What Ah are your battery’s ?
2x100Ah in parallel
No Bluetooth! It’s 2024!
Yeah that's a fair comment in 2024. It wasn't an issue for me when I reviewed it in 2022 but things have moved on. I'd expect they'll probably include that when they update this model.