As an Electronic technician here is some good advice for you. Never , ever charge your battery in your vehicle with an ac wall charger while it is connected to your vehicles electronics. The reason is that if for what ever reason you would have a voltage increase from the mains power or thermal runaway then you would fry your vehicle electronics. Always remove the vehicle positive terminal from the battery. You can however jumpstart from another vehicle like you would be doing right now. DC to DC chargers is for DC to DC.... not AC to dc to dc.. If your vehicle battery only was flat then you will need approximately need 10 to 15 hours on 10 amps to charge the first battery. Adding more batteries does double and triple the charging time. For an example. Drawing 10 Amps for 2 hours from a 100 amp hour battery means that you have used about 20% capacity. Charging the same battery with 10 amps will not fully charge that battery within 2 hours because as the battery gets fuller, the amps drop to eventually you will only be charging at about 1 or 2 amps. The time taken to charge the battery will be at least 8 hours.
I have the solution for you Andrew. I tow a camper trailer and in it I have a redarc BCDC40 to charge the two 100 Ahr AGM deep cycle batteries simply because of the distance from the car alternator and the resulting voltage drop. The problem is exactly the same, if the batteries in the camper were not fully charged when you stopped the DC to DC would drain the auxiliary battery to charge them. To overcome this I have a 100 amp relay mounted in the back of the car prior to the anderson plug which is switched through an oil pressure switch so it will never charge from the cars auxiliary battery, in my case, unless the car is running, even if you leave the ignition on accidentally. Luckily I found this out when researching the wiring and installation of the dc to dc charger before the actual fitting and it works perfectly. You could do a similar thing in your vehicle.
This is not a problem I’m trying to solve. And neither is this a mystery as to why it happened. It can and will happen to anyone using a DC-DC setup. It's the nature of how DC chargers work. All of them with the exception of those relying only on a trigger wire. The solution is to charge the auxiliary batteries first. It's that simple. When I learn something, I like to share it.
@@4xoverland I charge the aux batteries first. I have 360ah batteries charged via solar /Redarc BCDC1240. I also have a built in 30amp Victron mains charger, connected to the Aux batteries. If I ever need to charge the crank battery (which is rare) I have an alternator friendly switch to parallel the aux & crank batteries via 70mm2 cable (for extended electric winch use) , but it also doubles as a means of charging the crank battery when switched to parallel.
I'm a firm believer to always isolate a battery when using a 220V AC charger, regardless whether using 1 or multiple battery systems. It simply eliminates any possible issues from occurring. Thanks for the heads up Andrew! :)
This is so critical: as is clearly shown by Andrew's example. It's also the safest approach. I'm also a bit surprised at the notion of using solar to charge the crank battery. I'm more used to using solar and DC/DC chargers to charge the house batteries and isolating the crank battery so there are no loads on the crank battery other than originally intended by the manufacturer. The alternator should always be sufficient to charge the crank battery. Some alternators supply a varying amount of current, depending on their temperature.
Same here. If I am going to charge my starter battery with AC charger or solar panel, I always disconnect the wires from the negative terminal of the starter battery first.
All good info Andrew, I have had many problems to solve with battery issues as well. But I must say that it has been about 50 years since I left an ignition turned on with the motor off. I always use the trigger wire and a solenoid to connect the BC-BC. Cheers! Good Stuff!
Thank you Andrew I have just discovered your channel. This should end a long running debate among my friends. I had warned one of my friends that sitting on the beach listening to the test cricket will flatten your battery. It had happened to me. I suspected the trigger wire as you explain but he was adamant that the load from the radio could not possibly drain his starter. Sure enough I had to give him a jump start but he still didn't believe it was the radio at fault. Now we know it was probably a flat auxiliary combined with the the trigger wire connecting the two batteries.
Many thanks for the heads up on this. Just a couple of weeks into a van to camper conversion. I will add in an isolator in the circuit just to be sure. I was always taught never to leave the ignition on, that stems back to old petrol cars where depending where the points were your coil could burn out. We used to pull the coil wire off if we had to tow a dead car for the same reason.
In my setup I have a breaker where your fuse is and I can quickly switch off the Aux circuit when I need to charge the main battery and often leave it off where not on trips just using the roof solar to keep the Aux topped up.
Fascinating! Thanks for sharing your knowledge. This situation is certainly not one that people would immediately expect to occur. I’m about to design and roll out a system into a 4WD van and I will certainly put an isolation switch between the crank battery and my custom goodies - even just if starting with jumper leads etc I don’t want the aux system taking some of that load away.
Oh - before I forget, and hopefully this helps someone - I reckon if you want to hook up that ACC wire to trigger the DCDC, hook it up to Ignition / ON position instead. That way if you’re sitting in the car in ACC mode listening to the radio, your crank battery isn’t being drained to charge the aux battery.
Great video, Andrew and some excellent tips for us all. I'm using a manual cutoff switch in the dash for the DC-DC charger so that I can override the charger even when igintion is on.
Thanks for the info. In my situation I have my start battery purely for starting only. (Nothing connected besides low amp accessories on switches) the start battery will also be monitored. Then from my starter battery, it then connects to a smart isolator before connecting to my secondary battery. The second battery then has all the niknaks. This works only for older cars.
Love what you are doing with this series Andrew! Could you do a video on what compulsory maintenance we should be doing before trips? I am not very Mechanical savvy and would love a guide. Thanks.
Good to know. I knew there was a reason why I hooked up the optional manual disconnect switch. Thanks! In my case I’m charging a travel trailer with the tow vehicle - so the protocol needs to be always unplug the umbilicals when not needed.
Andrew, this doesn't make sense. I have basically the same setup and haven't experienced this problem. Typically DC/DC Chargers will switch off and stop charging the aux battery when the input drops below 11.8 volts. They typically won't turn on unless the input voltage is above 13.1 volts. So when you connected your mains charger to the battery, yes the voltage would have risen above 13.1 volts and the DC/DC charger would have turned on. This is the same principle and operation of the old Voltage Sensing Relays (VSRs). However, it's understandable that your mains charger would not have been able to cope with the load (current draw) of both batteries (if both were discharged). But what should have happened, is that the voltage from your mains charger would have progressively dropped as it wouldn't have been able to maintain the output current required to charge both batteries. Once the mains battery (with mains charger connected) dropped below 11.8 volts, the DC/DC charger should have turned off. The mains charger would then have been able to again start charging the main battery and the internal resistance of the battery would start rising and so would its voltage (Ohms Law). Once it reached 13.1 volts, the DC/DC charger would kick in again, and the whole sequence would start again. The end result over time, should have been that both batteries would be fully charged. So what's happened in your situation is a bit of a mystery.
The charger would have been connected to the same terminal as the DC-DC, so the DC-DC would've been seeing the input voltage of the charger this draining the battery. The charger would've been giving the DC-DC a false voltage reading of the main battery. The only way to get around this is to disconnect the DC-DC
@@nickscurr7062 My understanding is that external charger was connected in parallel to both the main battery and the DC/DC charger. So I still ask the question, why didn't the DC/DC charger turn off when the main battery and external charger voltage dropped to 11.8 volts. The external charger and main battery cannot have different voltages when connected together. Is there something here I don't understand? (I used to be an electrician...but not a very good one...LOL!).
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@@FastFless I'm afraid there is some "misunderstanding" between the DC/DC and the small charger (like pulse charging in the small charger that causes the voltage to raise repeatedly above the DC/DC switchoff levels). It is actually very unfortunate that both the devices are from Redarc and they don't work together!
@@FastFless , if the 10 amp charger was a simple linear constant current 10 amp device, then I believe it should be just as you have described. There must be something funny about the way the charger is delivering the charge that is tricking the DC/DC charger into staying on. It would be interesting to connect an oscilloscope and see exactly what is going on.
Another good video thanks Andrew. What I did was to install an old school 2nd battery solenoid, the old silver can type which only activates when the ignition is on. And yes you do have to charge the deep cycle separately if it is low. Cheers.
Will this happen with duel sensing dc to dc Chargers my solar input on the dc to dc will also charge the start battery no need to connect solar to the start battery
great info, Thank you! I am in the process of switching over my dual battery system due to the Tacoma smart alternator. This time I will place my second battery in the bed with a DC/DC charger............
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I'm just curious. Since You have lithium battery at back, it would charge fast during drive. Is home charging for battery maintenance purposes only? Right now im buying DC/DC charger and after your video i think about redesign my wiring and leaving inside cyrix ct. As always, thanks for great video.
Thanks Andrew, I was wondering what my problem was as the Main battery was often low on voltage. After watching your vid I went and checked my set up and it was so. I am now going to instal a relay controlled by ingnition to circumvent this.
I love DC-DC chargers, but thought it to be common sense to isolate the primary and aux batteries before connecting a 220V charger anywhere in the system, even if charging the aux battery/s and the DC-DC charger won't let current through to the primary. I always run a 12V 60A circuit breaker between the two battery systems, this way you can even use two 220V chargers at the same time to maintain both sets of batteries whilst the vehicle is not in use for some time.
How is the apparent charging voltage being maintained? As soon as the 50amp charger turns on it should pull the voltage down to just the battery voltage plus a little for the amount of power the charger can put in. Unless the DC to DC charger is set to run down to 13.2V or something that shouldn’t let the starter battery discharge to below where it can crank over your cruiser. If it is set to a very low cut off Voltage there should be a way of turning that up, with your setup the charging voltage shouldn’t fall below about 14v. Try measuring the voltage at the starter battery with theAC to DC and the DC to DC chargers running
David Cocks yep I saw a bunch of comments saying they were doing the same thing and I definitely believe it but I don’t see why you would want it to keep charging down to less than 13.5v probably higher if you have a powerful alternator the little 70w one in my ute easily holds 13.5v at 50A draw (I checked) and that is where I set my minimum. I only have a 5A charger and a 50A charger for AC the 5A only adds about 0.25V if the DC to DC is working flat out. But I can see a 10A one allowing the battery to go down below 12V with a 50A DC to DC one running if the DC to DC goes down to a really low voltage before shutting off. (my DC to DC is a dodgy Chinese one with a potentiometer each for the charging voltage cut offs (start-stop, drop, fast charge, slow charge) and dip switches to select other stuff and it says it will do 45A but it only does about 30 on any battery setup I have tried it on.
The battery charger is sending 14v 10 amp into the battery The 14v triggers the dc/dc the drain The dc/dc is only looking for 13v so.even thoigh the main battery is dead flat the charger is providing that voltage signal It could maybe be set to trigger a fault because of low amperage input but currently they're only set to look for that voltage signal
Glen Collins, I do agree with you. It is impossible, voltage must drop the moment the load exceed the maximum Amp the AC charger can supply. But the question remains, how does the crank battery then discharge? It just does not make sense?
CampX4 & Outdoor TV it’s being pulled out of the battery by the red arc DCDC and milking it flat as the 10 amp ac charger is trying keep up with THE 50amp load pulling through to the auxiliary, whilst this is going on the ac charger constantly sees a huge hole, tries in vain to fill it and cranks max voltage and amps into the bottomless pit.
Andrew, I realise you've identified the issue, but here's a suggestion for the future. I've fitted an Enerdrive 240v charger in the canopy of my Silverado. It has 3 separate "channels" for charging 3 separate banks of batteries. I have a somewhat similar set-up to you... A Redarc BCDC1225L and solar panels on the roof of the camper. When I plug the 240 volt cable into the caravan-style receptacle, the Enerdrive charges the Lithium battery, which is set to Channel One (in the canopy) first. It has the ability to choose what type of battery is being charged. Once the lithium battery is charged, it then turns its attention the Channel Two, which is the twin under-bonnet starting batteries. To achieve this latter function, I've simply tapped the Channel Two supply line into the cable that supplies the BCDC with its power from the front batteries. In your case, if you go ahead with another lithium battery (inside the canopy of your truck), then you can utilise all three separate channel of the Enerdrive. If you're interested in my Chevy, here's a write-up that was done a year or so ago: loaded4x4.com.au/issue-002#61
This is not a problem I’m trying to solve. And neither is this a mystery as to why it happened. It can and will happen to anyone using a DC-DC setup. It's the nature of how DC chargers work. All of them with the exception of those relying only on a trigger wire. The solution is to charge the auxiliary batteries first. It's that simple. When I learn something, I like to share it.
Makes perfect sense, thanks. Simply put, attaching the external battery charger brings the voltage of the main battery over the 'turn on' voltage for the BCDC. The BCDC will start pulling current from the main to charge the Aux. It does so at a rate higher than is being supplied to the main battery from the external charger. If I ever do need to charge my main from an external charger, I will pull the fuse from between the main battery and the BCDC. Probably a good idea if jumping from one battery to another. Cheers
Interesting stuff, I shall check for this problem shortly! I noticed that your new vehicle has a cyclonic snorkel head/pre filter. What do you think of them? Will you be changing it? I'm considering switching from an air ram to a cyclonic head.
Foretold is forewarned, thanks Andrew I would have killed my battery as well eventually and been scratching my head wondering why. And no doubt it would have been as the most inconvenient time imaginable. 👍
I was installing a BCDC 1225 this weekend, and found your clip pretty interesting. My install was in a camper, and it got me thinking… This issue looks like the starter battery needs to be better isolated from the house battery, and possibly it makes sense to treat it like a camper install and use a solenoid or an SBI to only link them when the ignition is on?
Well spotted Andrew. This is a big problem with DC-DC chargers. The charger will continue to run when the car is switched off as the cut off input voltage is 12.4v. Once the input drops below 12.4v the charger will stop until it reaches 13.4, however this often means your primary/starter battery is sitting around %70 SoC which is not a good place to be when it comes to starting big engines. For example: You have a 110A alternator, 100A isolated aux battery, a BCDC1240 charger, and a fridge. You pack the fridge a few days before going away and its on full time to get to temperature. The only driving you're doing is to the shops and back, perhaps an hour a day. If it's just bussing around locally, your alternator never gets consistent high RPM so its average output is around 30-50A (most are
Just installed one of the BCDC 40 amp redarc's can someone tell me how hot they normally get. During bulk charging mine gets Hot! All else seems well, charging normally etc... Thank you
Thanks for the video. I will now put an Anderson plug in my engine bay connecting from my main battery to my dc to dc charger so I can unplug it if I need to charge main battery.
I honestly thought everyone knew this....The clue is in the ‘voltage sensing’ aspect of the DC-DC. Also, DC-DC does not charge at 50 amps. That is simply the maximum it can charge at. The charge delivered depends on the aux battery’s state of discharge.
I typically see 5ish amps from my alternator? Would you say thats pretty low? I do have issues with power as dashboard and electrics turn off 10mins into night driving and come back on with battery light
NOTE. I chatted to the guys at Redarc and with Heiner. There is no mystery why this happened. It happened exactly why I said it did. It's a perfectly logical explanation. This is not a Redarc issue. I'm just using Redarc DC-chargers in my setup. All DC-DC chargers will do this because they rely on reading the voltage across the main battery to turn on. And if you use a trigger cable from the ignition, the start battery can be discharged if the ignition is left on, with the same result. The solution is very simple: if you have a DC-DC charger, if you want to charge the batteries without the engine running, charge the auxiliary battery first. What could be simpler?
Just follow the wiring diagram like everyone else and use the ignition trigger wire to turn the system on. If the ignition is turned off, no problem. Not sure why anyone would leave the key turned to ignition if the car isn't running.
So the solution - if you need to charge the start battery is to disconnect "aux" battery - before or after the BCDC - before charging the start battery (a good use case for a simple disconnect). (my BCDC Redarc 1225D is on Anderson connectors.) (NB - Redarc calls their system "Battery Charger Direct Current - BCDC, others call their units "Direct Current to Direct Current" Charger - DC-DC) Blue Trigger cable is specifically for low voltage / smart alternators.
I don't know if in any car. But in my VW T5 there is a D+ wire, which is a "alternator running" signal. From the factory the second battery charges only when the alternator is running. So not on ingnition. I thought there is a signal cable like this in any car.
Loved the way you explained this. Just a thought, doesn't this come down to the rule of using a battery charger that is of equal or higher current rating than that of the largest charger device in the vehicle circuit active at that time of charging?
I am in the process of changing my VSR for a 20A DC-DC, I was planning on using a DPDT switch or relay so that by default the camping batteries, when above trigger voltage (ie being solar charged) will keep the start battery full. When the vehicle is started, the relay will be triggered (by ignition switch) and reconfigure the DCDC to charge the camping batteries effectively from the alternator.
Andrew keep the VSR and and the DC DC charger behind. It isn't costing you any extra. Just apply the following wiring from redarc as if your DC DC charger was not in the same vehicle and that way you have a redundancy for cut off circuit. www.redarc.com.au/wiring-diagrams/how-to-wire-bcdc-caravan-vehicle-variable-voltage-alternator I wired the my wife and mine car like that because hers has a smart alternator. The DC to DC charger is attached to the portable battery box. If I didn't add a VSR to my car the charger would be draining my main battery too much. For hers to work she needed a VSR anyway. It was that or adding a switch to the portable battery box to turn on/off the blue ignition wire of the charger. But there would have been the problem of forgetting to do it and either arriving to a destination in her car with a not fully charged battery box, or flattening my battery overnight because of the low DC DC charger voltage cut off.
I also have a Ctek 250sa DC to DC charger hooked up to a solar panel (because it's not a daily drive) it charges the 2nd battery and when that's charged it starts charging the start battery.
Exactly. Take any overflow from auxiliary battery bank back to the starter battery. I’m looking at a dual-sensing VSR for this purpose. The Jaycar one has cut-in at 13.3V and cut-out at 12.8V.
This is really a new problem when the auxiliary battery is Lithium. Previously the AGMs commonly used would rarely accept 50 amps charge, no matter what the rating of the DC-DC charger. The solution is simple - if you can afford Redarc 50A DC-DC charger (most of us can't, and are perfectly well served with a 20A unit) you can afford a 50A AC battery charger. End of issue. You can also wire up a dash switch into the IGN trigger wire so you can manually override on those occasions when you need to leave the IGN on for long periods.
This is not a problem I’m trying to solve. And neither is this a mystery as to why it happened. It can and will happen to anyone using a DC-DC setup. It's the nature of how DC chargers work. All of them with the exception of those relying only on a trigger wire. The solution is to charge the auxiliary batteries first. It's that simple.
Nice work Andrew, If I may my 2cts: trouble starts when manufactors paralel batteries; the solution is use more powerfull ( more current) chargers, actually like they do sizing the alternator; of course the batteries last less. ( it happened in the past with 6v and the trucks 12v) best, Pedro
U should have ur BCDC charger on the trigger switch u mentioned. The trigger switch can also be connected to a wire that only receives voltage when the car is running. U could also add a breaker so as the BCDC charger doesn’t see the voltage when ur trying to charge ur main......
One can also add a switch on the positive lead connecting the redarc to your start battery. Turn it on or off to disconect the redarc to the starter battery and charge it without. Anyways, thanks for sharing the experience, dmuch preferablento learn it from you than in the trail.
Andrew, possible solution, mount a solar panel on your garage roof and run cables down for easy connect on to the yellow cable (solar input) on the Redarc. When the Redarc sense solar input, it will not accept input from the main battery. Therefore, as long as you only have your 10amp start battery charger on at the same time as the solar connected to the aux, then you will effectively have separated charging of batteries. Regards, Sean
Another, solution, in the red line between the start battery and the Redarc, add an old style silver 100 amp continuous duty solenoid (the type we all used to used in simple dual battery set ups years ago) then trigger this from the windscreen wiper motor. Then, the start battery can only feed the Redarc when the engine is running.
i have no problems,my dc todc charger wont draw onece it reaches 10.5 volts,plus i use a dedicated deep cycle battery charger,it will charge two 120 amp hour batters plus the start battry,correct your set up.you may need a voltage sensative relay.
This is not a problem I’m trying to solve. And neither is this a mystery as to why it happened. It can and will happen to anyone using a DC-DC setup. It's the nature of how DC chargers work. All of them with the exception of those relying only on a trigger wire. The solution is to charge the auxiliary batteries first. It's that simple. When I learn something, I like to share it.
Not an issue with CTEK 250sa with smartpass check it out ! Have had ctek on my cars now for 7 years and never flat batteries, and my car is not a daily driver either.
CTEK also recommend attaching the float charger to the Aux battery side. The same can happen with CTEK if your float charger is able to lift the main battery voltage.
Hi Andrew. I'd suggest re- approaching Redarc with regards to apsolute clarification as to this blue wire and voltage cut off. Someone has to be wrong, otherwise state of the art Redarc starts to look like well outdated Redarc (and any other dcdc charger that works in a similar way). I truly believe it's not Redarc as instructions despite not being so clear, suggest it's all down to this blue wire not being connected. Now a great video would be to connect the blue wire and do the same test, then try with the ignition left on to test voltage cut out, or as the case may be no voltage cut out with a mains charger connected.
This is not a problem I’m trying to solve. And neither is this a mystery as to why it happened. It can and will happen to anyone using a DC-DC setup. It's the nature of how DC chargers work. All of them with the exception of those relying only on a trigger wire. The solution is to charge the auxiliary batteries first. It's that simple.
@@4xoverland Yes true, it is a simple solution. However I'm more thinking along the lines of alternator output - I'm running a smart alternator as fitted by Mr Toyota, if I remember correctly you have changed yours or was that just the Africa terrain tamer build? So a smart alternator can drop output to something like 8 or 9 volts, is there a scinario where by your starter battery can be fully charged in the eyes of the smart alternator however your aux batteries are near depleted and the dcdc charger pulls your starter battery down to a point where by it can no longer start your engine despite the alternator still effectively charging? My theory is the smart alternator should be smart enough to figure this out and fast enough/be able to provide enough amps to starter battery to cope. Scinario 2 - your alternator becomes defective and cannot provide enough amps to keep your starter battery topped up, the dcdc charger will happily help kill the starter battery much quicker, this drops to a point where your vehicle electrics cannot run and your lose engine and all "factory" vehicle power. (It would happen anyway but the dcdc has made it happen much quicker. O.k. alternator failure isn't that common without warning and if it did happen your red dash charge light comes on so you can pull the dcdc fuse and potentially divert solar power to give the starter battery some form of charge - that would be pretty pointless in the U.K though, with our weather! Perhaps I'm overthinking the perfect storm combination? I think I'm into my 6th or 7th year of unbroken patreon support for you Andrew. Keep doing what you are doing, we all get a great amount from your videos. I truly like the fact you are unbiased and not worried about saying the truth. Do you have any future trips planned with Mr Paul Marsh? Stay safe and let's ride this storm out one way or another...
Awesome video, I get it. I am also having another weird problem. After using the fridge for the day and I get back in and drive, my dash lights start coming on. I am sure this is the computer shutting things down for lack of power. Sometimes it is when I underrate. When the second battery if full there is never any problems. I have 120 series Prado 3lt desire. I have wonded about the Alternator but am now wondering about the dcdc charger. Any thoughts?
What if you put a switch in the cabin to control when the charger is allowed to operate, normally it would be in the ON position so it can operate as per normal, but if you want to do work on the car with ignition on, for a period of time the switch will disable the charger, maybe a red flashing light also when it's "off" to warn you so you don't get to the destination and it's wasn't charging because you forgot to turn it back on ?
I see he mentioned the trigger cable. This is what i meant. If he had this trigger cable hooked up, it would have told the charger that the vehicle wasnt on, and therefor would have isolated the batteries regardless of the voltage on the start battery?
Good point. I am about to install a redarc DC/DC into my jeep with an AGM and LiFePO4 auxillary battery and I have been looking for a AC battery charger to do what you are doing.
On an isolator setup redarc sbi12, charging both a start and dual purpose marine stoaway at the same time off a battery maintainer at 2amps. I have been separating them when stored in the shed would that be harmful with both on the one. Got a better 5amp victron one that would be easier to just plug into and do both. I know the isolator isn't as efficient but for a basic under bonnet setup that I wanted to be able to jump start myself it works good enough. Also add those large fuses are not the greatest usually the holders cannot stand up to the current, midi are far better and easier to store as spares
User-induced issue. There are many ways to do it correctly and one way to do it incorrectly (by triggering the dc-dc with a tiny mains charger on the starter side). Either isolate when shore charging starter batt with a tiny mains charger or use a mains charger of the appropriate size. Or charge aux back from mains with a dc-dc that maintains starter batt. Patient: it hurts when I do [this]! Doctor: stop doing it and it won't hurt anymore.
Was kind-of aware of this but good to be told, probably could make a safety circuit for this but a Big Label on the charger will be the cheapest solution.
Connect the trigger wire through a relay. Pin 30 to key on power, 86 to key on power, pin 87a to dcdc trigger wire and 85 to alternator thin wire which grounds the battery warning on dash, so when alternator is working the DC DC will sense and turn on the charging.
Hi Andrew, in your opinion, how can we avoid drain out the starter battery ? By not connecting the ACC wire(if not smart alternator)? or simply add a switch by the starter battery and switch it off if turn on ACC (engine offf)? So, if someone never leave the ACC 'on' whatever condition it is, the starter battery won't be fltten, it this correct? By different manufacturers, is your findings applies to all of them? (Renogy, Atempower, Redarc, Hisae, Projecta....)? What if there is a solar panel connected with 5-10A current presented? thanks !!
I was looking at the Redarc wiring guide that indicates a resettable fuse should be used in the setup. Therefore to charge each of the batteries wouldn't you just break the fuse during the charging cycle and therefore only charge the one you want?
I have a TS800 DC/DC converter which has a vibrationsensor to check if engine is running, works fine, also when ac charger is hooked up. Except on a long trip on a ferry where it completely drained the starter battery 🤔
It may be worth noting that every time you charge this way you are depleting the crank battery far too much even if you leave it on for the full cycle. It's being drained way down then recharged slowly, bad practice. Better to charge house batteries separately.
I installed a switchable circuit breaker between the main battery and the DC to DC charger to separate the two Systems if I needed to. I did however learn the hard way about what you are talking about because I forgot to turn the switch off
So you are saying, when the engine is on, if the difference between the alternator output amps and draw from the main battery for various components are less than 50amps, still the main battery will discharge?
Good point, and correct. That’s why you need to match/balance all electrical equipment in your circuits. He said his alternator puts out 170A, so if all vehicle systems are using up to 120A maximum, then I guess he’s OK under alternator power. However, it sounds like it might be a contributing factor to his starter battery being drained. When he said he had a 50A dc-dc charger, I immediately thought that was overkill, unless his alternator can indeed keep up with total demands, and unless he has a bank of auxiliary batteries in the 200AH plus range. Very good point buddy.
That's a good heads up on protecting your starting battery especially these days because a lot of new cars run their computer systems of this battery. When the main battery is drained the system needs to be reset and then comes the hard part finding passwords. This would be a nightmare if your in the middle of nowhere without a dealer or a auto electrician around. Solving this problem for you was good,your able to know how to fix it. I think it's a good idea for any 4x4 driver to practice these scenarios just in case it does happen. For me if l bought a new 4x4 l would disconnect the battery at home to see what would happen to the system.😁👍
Passwords ?, the only thing that needs resetting on my 2019 Ranger is the Auto drivers window, it resorts back to non auto, everything else works fine after a battery disconnection just like any decent 4WD should be, as the ECU'S have self powered backups inside, if a 4WD is designed like you say, then I would stay away from it.
Sounds like these expensive systems have plenty of traps if not set up or used right. For now, I just have a really cheap set up of the main battery for all the original vehicle systems (1970s Land Rover, so very basic), and a second battery for accessories like power sockets, stereo, auxiliary lights, seat and screen heating and so on, any thing not essential to driving. They’re linked by a heavy relay which it triggered by the alternator diode pack (dash warning light terminal on the back of the alternator). It works very simply, so the batteries are isolated unless the alternator is providing a charge. I want to add solar for the auxiliary battery. The primary shouldn’t need it - main systems are drawing power if the vehicle isn’t being used, and in such an unlikely event, the engine could be started by jumping (a hard wired isolator connecting only for emergencies) from the auxiliary battery. There is a lot to be said for simplicity.
Just the man I wanted to ask a couple things. Can I safely charge my lithium auxiliary battery with a 20 amp AC/DC chargerdirectly if half depleted while my Redarc bcdc is connected without affecting the whole setup? Regards, Steve
no. Some Lithium battery sellers will tell you you can. But the voltages are not the same and while it will accept a charge direct from the alternator, it will and can never charge it properly or efficiently. But your Redarc BC-DC will charge it perfectly.
Overland Drive I use the same dual charger system for aux and main battery, just leave a shore line plugged in and both batteries are charged and maintained, easy. Worth buying a decent dual charger
Thank you Andrew, I always follow your channel with great interest and I particularly appreciate your willingness to share freely your knowledge and insights. I would be equally keen to hear expert opinion from Redarc on your observations. Presuming you have this would you share those with us too perhaps?
Here’s what Redarc said.... In regards to the connection of the blue trigger wire on BCDC, the following needs to apply: 1) If your vehicle has a standard alternator type (fixed voltage), the blue wire can be left disconnected 2) If your vehicle has a smart alternator type (temeprature compensating or variable voltage), the blue wire needs to be connected to an ignition source 3) If you are unsure of what alternator type you have, it is best to connect the blue wire to ignition We have indeed seen the video mentioned and it does explain the connection of the blue wire, just not in great depth as to how it operates.
As an Electronic technician here is some good advice for you. Never , ever charge your battery in your vehicle with an ac wall charger while it is connected to your vehicles electronics. The reason is that if for what ever reason you would have a voltage increase from the mains power or thermal runaway then you would fry your vehicle electronics. Always remove the vehicle positive terminal from the battery. You can however jumpstart from another vehicle like you would be doing right now. DC to DC chargers is for DC to DC.... not AC to dc to dc.. If your vehicle battery only was flat then you will need approximately need 10 to 15 hours on 10 amps to charge the first battery. Adding more batteries does double and triple the charging time. For an example. Drawing 10 Amps for 2 hours from a 100 amp hour battery means that you have used about 20% capacity. Charging the same battery with 10 amps will not fully charge that battery within 2 hours because as the battery gets fuller, the amps drop to eventually you will only be charging at about 1 or 2 amps. The time taken to charge the battery will be at least 8 hours.
I have the solution for you Andrew.
I tow a camper trailer and in it I have a redarc BCDC40 to charge the two 100 Ahr AGM deep cycle batteries simply because of the distance from the car alternator and the resulting voltage drop. The problem is exactly the same, if the batteries in the camper were not fully charged when you stopped the DC to DC would drain the auxiliary battery to charge them.
To overcome this I have a 100 amp relay mounted in the back of the car prior to the anderson plug which is switched through an oil pressure switch so it will never charge from the cars auxiliary battery, in my case, unless the car is running, even if you leave the ignition on accidentally. Luckily I found this out when researching the wiring and installation of the dc to dc charger before the actual fitting and it works perfectly. You could do a similar thing in your vehicle.
This is not a problem I’m trying to solve. And neither is this a mystery as to why it happened. It can and will happen to anyone using a DC-DC setup. It's the nature of how DC chargers work. All of them with the exception of those relying only on a trigger wire. The solution is to charge the auxiliary batteries first. It's that simple. When I learn something, I like to share it.
@@4xoverland I charge the aux batteries first. I have 360ah batteries charged via solar /Redarc BCDC1240. I also have a built in 30amp Victron mains charger, connected to the Aux batteries. If I ever need to charge the crank battery (which is rare) I have an alternator friendly switch to parallel the aux & crank batteries via 70mm2 cable (for extended electric winch use) , but it also doubles as a means of charging the crank battery when switched to parallel.
I'm a firm believer to always isolate a battery when using a 220V AC charger, regardless whether using 1 or multiple battery systems. It simply eliminates any possible issues from occurring. Thanks for the heads up Andrew! :)
This is so critical: as is clearly shown by Andrew's example. It's also the safest approach. I'm also a bit surprised at the notion of using solar to charge the crank battery. I'm more used to using solar and DC/DC chargers to charge the house batteries and isolating the crank battery so there are no loads on the crank battery other than originally intended by the manufacturer. The alternator should always be sufficient to charge the crank battery. Some alternators supply a varying amount of current, depending on their temperature.
Same here. If I am going to charge my starter battery with AC charger or solar panel, I always disconnect the wires from the negative terminal of the starter battery first.
All good info Andrew, I have had many problems to solve with battery issues as well. But I must say that it has been about 50 years since I left an ignition turned on with the motor off. I always use the trigger wire and a solenoid to connect the BC-BC. Cheers! Good Stuff!
Thank you Andrew I have just discovered your channel. This should end a long running debate among my friends. I had warned one of my friends that sitting on the beach listening to the test cricket will flatten your battery. It had happened to me. I suspected the trigger wire as you explain but he was adamant that the load from the radio could not possibly drain his starter. Sure enough I had to give him a jump start but he still didn't believe it was the radio at fault. Now we know it was probably a flat auxiliary combined with the the trigger wire connecting the two batteries.
Many thanks for the heads up on this. Just a couple of weeks into a van to camper conversion. I will add in an isolator in the circuit just to be sure. I was always taught never to leave the ignition on, that stems back to old petrol cars where depending where the points were your coil could burn out. We used to pull the coil wire off if we had to tow a dead car for the same reason.
In my setup I have a breaker where your fuse is and I can quickly switch off the Aux circuit when I need to charge the main battery and often leave it off where not on trips just using the roof solar to keep the Aux topped up.
Fascinating! Thanks for sharing your knowledge. This situation is certainly not one that people would immediately expect to occur. I’m about to design and roll out a system into a 4WD van and I will certainly put an isolation switch between the crank battery and my custom goodies - even just if starting with jumper leads etc I don’t want the aux system taking some of that load away.
Oh - before I forget, and hopefully this helps someone - I reckon if you want to hook up that ACC wire to trigger the DCDC, hook it up to Ignition / ON position instead. That way if you’re sitting in the car in ACC mode listening to the radio, your crank battery isn’t being drained to charge the aux battery.
Great video, Andrew and some excellent tips for us all. I'm using a manual cutoff switch in the dash for the DC-DC charger so that I can override the charger even when igintion is on.
Thanks for the info. In my situation I have my start battery purely for starting only. (Nothing connected besides low amp accessories on switches) the start battery will also be monitored. Then from my starter battery, it then connects to a smart isolator before connecting to my secondary battery. The second battery then has all the niknaks. This works only for older cars.
Love what you are doing with this series Andrew! Could you do a video on what compulsory maintenance we should be doing before trips? I am not very Mechanical savvy and would love a guide. Thanks.
Glad you shared this. Thank you Andrew.
Very useful info Andrew, thank you.
Thanks for the video Andrew, I remembered the tip a couple of weeks ago when I had to charge my start battery.
Good to know. I knew there was a reason why I hooked up the optional manual disconnect switch. Thanks!
In my case I’m charging a travel trailer with the tow vehicle - so the protocol needs to be always unplug the umbilicals when not needed.
Andrew, this doesn't make sense. I have basically the same setup and haven't experienced this problem.
Typically DC/DC Chargers will switch off and stop charging the aux battery when the input drops below 11.8 volts. They typically won't turn on unless the input voltage is above 13.1 volts. So when you connected your mains charger to the battery, yes the voltage would have risen above 13.1 volts and the DC/DC charger would have turned on. This is the same principle and operation of the old Voltage Sensing Relays (VSRs).
However, it's understandable that your mains charger would not have been able to cope with the load (current draw) of both batteries (if both were discharged).
But what should have happened, is that the voltage from your mains charger would have progressively dropped as it wouldn't have been able to maintain the output current required to charge both batteries. Once the mains battery (with mains charger connected) dropped below 11.8 volts, the DC/DC charger should have turned off.
The mains charger would then have been able to again start charging the main battery and the internal resistance of the battery would start rising and so would its voltage (Ohms Law). Once it reached 13.1 volts, the DC/DC charger would kick in again, and the whole sequence would start again. The end result over time, should have been that both batteries would be fully charged.
So what's happened in your situation is a bit of a mystery.
The charger would have been connected to the same terminal as the DC-DC, so the DC-DC would've been seeing the input voltage of the charger this draining the battery. The charger would've been giving the DC-DC a false voltage reading of the main battery. The only way to get around this is to disconnect the DC-DC
Kim Flesser 240v charger pumps out a constant 13+ volts across the terminal therefore dcdc keeps charging..
@@nickscurr7062 My understanding is that external charger was connected in parallel to both the main battery and the DC/DC charger. So I still ask the question, why didn't the DC/DC charger turn off when the main battery and external charger voltage dropped to 11.8 volts. The external charger and main battery cannot have different voltages when connected together. Is there something here I don't understand? (I used to be an electrician...but not a very good one...LOL!).
@@FastFless I'm afraid there is some "misunderstanding" between the DC/DC and the small charger (like pulse charging in the small charger that causes the voltage to raise repeatedly above the DC/DC switchoff levels). It is actually very unfortunate that both the devices are from Redarc and they don't work together!
@@FastFless , if the 10 amp charger was a simple linear constant current 10 amp device, then I believe it should be just as you have described. There must be something funny about the way the charger is delivering the charge that is tricking the DC/DC charger into staying on. It would be interesting to connect an oscilloscope and see exactly what is going on.
That‘s a very good one, have never thought about that. Thank you for sharing that one.
Another good video thanks Andrew. What I did was to install an old school 2nd battery solenoid, the old silver can type which only activates when the ignition is on. And yes you do have to charge the deep cycle separately if it is low. Cheers.
Since you're trying to centralise weight between the axles have you considered moving the start battery closer to the firewall?
Very good topic. Thanks for sharing!
Will this happen with duel sensing dc to dc Chargers my solar input on the dc to dc will also charge the start battery no need to connect solar to the start battery
great info, Thank you! I am in the process of switching over my dual battery system due to the Tacoma smart alternator. This time I will place my second battery in the bed with a DC/DC charger............
I'm just curious. Since You have lithium battery at back, it would charge fast during drive.
Is home charging for battery maintenance purposes only? Right now im buying DC/DC charger and after your video i think about redesign my wiring and leaving inside cyrix ct.
As always, thanks for great video.
Thanks for good advice. I have’nt thought about. But you are right.
Hey Andrew, have you considered an Auto Conversion on your 79 for this build? What are your thoughts on an Auto 79?
Thanks Andrew, I was wondering what my problem was as the Main battery was often low on voltage. After watching your vid I went and checked my set up and it was so. I am now going to instal a relay controlled by ingnition to circumvent this.
No need to do that just put your battery charger On your house battery Once it Topped off it'll backfeed to your starting battery And charge it
My Redarc does just the same thing, but the Ctek did not do it. Good job I have a charger isolator fitted in my truck
Awesome detective work ASPW. How many people have been caught out by this in COVID. I now realise that is what has happened to me two weeks ago.
Very informative. Thank you.
Thank you Andrew that’s very useful review
So how are you going to aleiviate the problem while still being able to charge both batteries in various ways?
I love DC-DC chargers, but thought it to be common sense to isolate the primary and aux batteries before connecting a 220V charger anywhere in the system, even if charging the aux battery/s and the DC-DC charger won't let current through to the primary.
I always run a 12V 60A circuit breaker between the two battery systems, this way you can even use two 220V chargers at the same time to maintain both sets of batteries whilst the vehicle is not in use for some time.
Agree Dirk, Isolation prevents any 'oops moments' , simple and effective. :)
Agreed. Circuit breaker to isolate. Simple and effective.
Another great video Sir
How is the apparent charging voltage being maintained? As soon as the 50amp charger turns on it should pull the voltage down to just the battery voltage plus a little for the amount of power the charger can put in.
Unless the DC to DC charger is set to run down to 13.2V or something that shouldn’t let the starter battery discharge to below where it can crank over your cruiser.
If it is set to a very low cut off Voltage there should be a way of turning that up, with your setup the charging voltage shouldn’t fall below about 14v.
Try measuring the voltage at the starter battery with theAC to DC and the DC to DC chargers running
Mine does just the same as Andrew says
David Cocks yep I saw a bunch of comments saying they were doing the same thing and I definitely believe it but I don’t see why you would want it to keep charging down to less than 13.5v probably higher if you have a powerful alternator the little 70w one in my ute easily holds 13.5v at 50A draw (I checked) and that is where I set my minimum. I only have a 5A charger and a 50A charger for AC the 5A only adds about 0.25V if the DC to DC is working flat out. But I can see a 10A one allowing the battery to go down below 12V with a 50A DC to DC one running if the DC to DC goes down to a really low voltage before shutting off.
(my DC to DC is a dodgy Chinese one with a potentiometer each for the charging voltage cut offs (start-stop, drop, fast charge, slow charge) and dip switches to select other stuff and it says it will do 45A but it only does about 30 on any battery setup I have tried it on.
The battery charger is sending 14v 10 amp into the battery
The 14v triggers the dc/dc the drain
The dc/dc is only looking for 13v so.even thoigh the main battery is dead flat the charger is providing that voltage signal
It could maybe be set to trigger a fault because of low amperage input but currently they're only set to look for that voltage signal
Glen Collins, I do agree with you. It is impossible, voltage must drop the moment the load exceed the maximum Amp the AC charger can supply. But the question remains, how does the crank battery then discharge? It just does not make sense?
CampX4 & Outdoor TV it’s being pulled out of the battery by the red arc DCDC and milking it flat as the 10 amp ac charger is trying keep up with THE 50amp load pulling through to the auxiliary, whilst this is going on the ac charger constantly sees a huge hole, tries in vain to fill it and cranks max voltage and amps into the bottomless pit.
Andrew, I realise you've identified the issue, but here's a suggestion for the future. I've fitted an Enerdrive 240v charger in the canopy of my Silverado. It has 3 separate "channels" for charging 3 separate banks of batteries. I have a somewhat similar set-up to you... A Redarc BCDC1225L and solar panels on the roof of the camper.
When I plug the 240 volt cable into the caravan-style receptacle, the Enerdrive charges the Lithium battery, which is set to Channel One (in the canopy) first. It has the ability to choose what type of battery is being charged.
Once the lithium battery is charged, it then turns its attention the Channel Two, which is the twin under-bonnet starting batteries. To achieve this latter function, I've simply tapped the Channel Two supply line into the cable that supplies the BCDC with its power from the front batteries.
In your case, if you go ahead with another lithium battery (inside the canopy of your truck), then you can utilise all three separate channel of the Enerdrive.
If you're interested in my Chevy, here's a write-up that was done a year or so ago: loaded4x4.com.au/issue-002#61
This is not a problem I’m trying to solve. And neither is this a mystery as to why it happened. It can and will happen to anyone using a DC-DC setup. It's the nature of how DC chargers work. All of them with the exception of those relying only on a trigger wire. The solution is to charge the auxiliary batteries first. It's that simple. When I learn something, I like to share it.
Makes perfect sense, thanks. Simply put, attaching the external battery charger brings the voltage of the main battery over the 'turn on' voltage for the BCDC. The BCDC will start pulling current from the main to charge the Aux. It does so at a rate higher than is being supplied to the main battery from the external charger. If I ever do need to charge my main from an external charger, I will pull the fuse from between the main battery and the BCDC. Probably a good idea if jumping from one battery to another. Cheers
Interesting stuff, I shall check for this problem shortly! I noticed that your new vehicle has a cyclonic snorkel head/pre filter. What do you think of them? Will you be changing it? I'm considering switching from an air ram to a cyclonic head.
Foretold is forewarned, thanks Andrew I would have killed my battery as well eventually and been scratching my head wondering why. And no doubt it would have been as the most inconvenient time imaginable. 👍
I was installing a BCDC 1225 this weekend, and found your clip pretty interesting. My install was in a camper, and it got me thinking… This issue looks like the starter battery needs to be better isolated from the house battery, and possibly it makes sense to treat it like a camper install and use a solenoid or an SBI to only link them when the ignition is on?
Well spotted Andrew.
This is a big problem with DC-DC chargers. The charger will continue to run when the car is switched off as the cut off input voltage is 12.4v. Once the input drops below 12.4v the charger will stop until it reaches 13.4, however this often means your primary/starter battery is sitting around %70 SoC which is not a good place to be when it comes to starting big engines.
For example: You have a 110A alternator, 100A isolated aux battery, a BCDC1240 charger, and a fridge. You pack the fridge a few days before going away and its on full time to get to temperature. The only driving you're doing is to the shops and back, perhaps an hour a day. If it's just bussing around locally, your alternator never gets consistent high RPM so its average output is around 30-50A (most are
Just installed one of the BCDC 40 amp redarc's can someone tell me how hot they normally get. During bulk charging mine gets Hot! All else seems well, charging normally etc... Thank you
Wow, just wow, thank you for sharing.
very interesting. thanks for sharing that great tip.
Thanks for the video. I will now put an Anderson plug in my engine bay connecting from my main battery to my dc to dc charger so I can unplug it if I need to charge main battery.
I honestly thought everyone knew this....The clue is in the ‘voltage sensing’ aspect of the DC-DC. Also, DC-DC does not charge at 50 amps. That is simply the maximum it can charge at. The charge delivered depends on the aux battery’s state of discharge.
I typically see 5ish amps from my alternator? Would you say thats pretty low? I do have issues with power as dashboard and electrics turn off 10mins into night driving and come back on with battery light
Yeah, if only charging at 5 A most of the time you seem to have an alternator or bad starting battery issue.
NOTE. I chatted to the guys at Redarc and with Heiner. There is no mystery why this happened. It happened exactly why I said it did. It's a perfectly logical explanation. This is not a Redarc issue. I'm just using Redarc DC-chargers in my setup. All DC-DC chargers will do this because they rely on reading the voltage across the main battery to turn on. And if you use a trigger cable from the ignition, the start battery can be discharged if the ignition is left on, with the same result. The solution is very simple: if you have a DC-DC charger, if you want to charge the batteries without the engine running, charge the auxiliary battery first. What could be simpler?
Just follow the wiring diagram like everyone else and use the ignition trigger wire to turn the system on. If the ignition is turned off, no problem. Not sure why anyone would leave the key turned to ignition if the car isn't running.
So the solution - if you need to charge the start battery is to disconnect "aux" battery - before or after the BCDC - before charging the start battery (a good use case for a simple disconnect). (my BCDC Redarc 1225D is on Anderson connectors.)
(NB - Redarc calls their system "Battery Charger Direct Current - BCDC, others call their units "Direct Current to Direct Current" Charger - DC-DC)
Blue Trigger cable is specifically for low voltage / smart alternators.
4xoverland would a circuit breaker with switch work? Install near the mains battery and when you put on the charger flip the switch on /off
I don't know if in any car. But in my VW T5 there is a D+ wire, which is a "alternator running" signal. From the factory the second battery charges only when the alternator is running. So not on ingnition. I thought there is a signal cable like this in any car.
@@kadmow seems like redarc are handicapping themselves for no apparent reason
great information thank you.
Loved the way you explained this. Just a thought, doesn't this come down to the rule of using a battery charger that is of equal or higher current rating than that of the largest charger device in the vehicle circuit active at that time of charging?
I am in the process of changing my VSR for a 20A DC-DC, I was planning on using a DPDT switch or relay so that by default the camping batteries, when above trigger voltage (ie being solar charged) will keep the start battery full. When the vehicle is started, the relay will be triggered (by ignition switch) and reconfigure the DCDC to charge the camping batteries effectively from the alternator.
Andrew keep the VSR and and the DC DC charger behind. It isn't costing you any extra.
Just apply the following wiring from redarc as if your DC DC charger was not in the same vehicle and that way you have a redundancy for cut off circuit.
www.redarc.com.au/wiring-diagrams/how-to-wire-bcdc-caravan-vehicle-variable-voltage-alternator
I wired the my wife and mine car like that because hers has a smart alternator. The DC to DC charger is attached to the portable battery box. If I didn't add a VSR to my car the charger would be draining my main battery too much. For hers to work she needed a VSR anyway.
It was that or adding a switch to the portable battery box to turn on/off the blue ignition wire of the charger. But there would have been the problem of forgetting to do it and either arriving to a destination in her car with a not fully charged battery box, or flattening my battery overnight because of the low DC DC charger voltage cut off.
I also have a Ctek 250sa DC to DC charger hooked up to a solar panel (because it's not a daily drive) it charges the 2nd battery and when that's charged it starts charging the start battery.
Exactly. Take any overflow from auxiliary battery bank back to the starter battery. I’m looking at a dual-sensing VSR for this purpose. The Jaycar one has cut-in at 13.3V and cut-out at 12.8V.
This is really a new problem when the auxiliary battery is Lithium. Previously the AGMs commonly used would rarely accept 50 amps charge, no matter what the rating of the DC-DC charger. The solution is simple - if you can afford Redarc 50A DC-DC charger (most of us can't, and are perfectly well served with a 20A unit) you can afford a 50A AC battery charger. End of issue. You can also wire up a dash switch into the IGN trigger wire so you can manually override on those occasions when you need to leave the IGN on for long periods.
This is not a problem I’m trying to solve. And neither is this a mystery as to why it happened. It can and will happen to anyone using a DC-DC setup. It's the nature of how DC chargers work. All of them with the exception of those relying only on a trigger wire. The solution is to charge the auxiliary batteries first. It's that simple.
Nice work Andrew, If I may my 2cts: trouble starts when manufactors paralel batteries; the solution is use more powerfull ( more current) chargers, actually like they do sizing the alternator; of course the batteries last less. ( it happened in the past with 6v and the trucks 12v)
best, Pedro
U should have ur BCDC charger on the trigger switch u mentioned. The trigger switch can also be connected to a wire that only receives voltage when the car is running. U could also add a breaker so as the BCDC charger doesn’t see the voltage when ur trying to charge ur main......
One can also add a switch on the positive lead connecting the redarc to your start battery. Turn it on or off to disconect the redarc to the starter battery and charge it without.
Anyways, thanks for sharing the experience, dmuch preferablento learn it from you than in the trail.
So what you are saying is that the DC to DC charger is sensing the 10A battery charger and not switching off and therefore draining the crank battery?
Andrew, possible solution, mount a solar panel on your garage roof and run cables down for easy connect on to the yellow cable (solar input) on the Redarc. When the Redarc sense solar input, it will not accept input from the main battery. Therefore, as long as you only have your 10amp start battery charger on at the same time as the solar connected to the aux, then you will effectively have separated charging of batteries.
Regards, Sean
Another, solution, in the red line between the start battery and the Redarc, add an old style silver 100 amp continuous duty solenoid (the type we all used to used in simple dual battery set ups years ago) then trigger this from the windscreen wiper motor. Then, the start battery can only feed the Redarc when the engine is running.
i have no problems,my dc todc charger wont draw onece it reaches 10.5 volts,plus i use a dedicated deep cycle battery charger,it will charge two 120 amp hour batters plus the start battry,correct your set up.you may need a voltage sensative relay.
This is not a problem I’m trying to solve. And neither is this a mystery as to why it happened. It can and will happen to anyone using a DC-DC setup. It's the nature of how DC chargers work. All of them with the exception of those relying only on a trigger wire. The solution is to charge the auxiliary batteries first. It's that simple. When I learn something, I like to share it.
Not an issue with CTEK 250sa with smartpass check it out ! Have had ctek on my cars now for 7 years and never flat batteries, and my car is not a daily driver either.
That solution will also charge the start battery by solar when aux battery is full.
CTEK also recommend attaching the float charger to the Aux battery side. The same can happen with CTEK if your float charger is able to lift the main battery voltage.
Ģg^g^gg^^v
Thanks Andrew
Wouldn’t trickle charging a lithium battery like that not do it any good? I thought that’s why you need a specific charge profile for lithium.
thanks for the handy hint
Hi Andrew. I'd suggest re- approaching Redarc with regards to apsolute clarification as to this blue wire and voltage cut off. Someone has to be wrong, otherwise state of the art Redarc starts to look like well outdated Redarc (and any other dcdc charger that works in a similar way). I truly believe it's not Redarc as instructions despite not being so clear, suggest it's all down to this blue wire not being connected. Now a great video would be to connect the blue wire and do the same test, then try with the ignition left on to test voltage cut out, or as the case may be no voltage cut out with a mains charger connected.
This is not a problem I’m trying to solve. And neither is this a mystery as to why it happened. It can and will happen to anyone using a DC-DC setup. It's the nature of how DC chargers work. All of them with the exception of those relying only on a trigger wire. The solution is to charge the auxiliary batteries first. It's that simple.
@@4xoverland Yes true, it is a simple solution. However I'm more thinking along the lines of alternator output - I'm running a smart alternator as fitted by Mr Toyota, if I remember correctly you have changed yours or was that just the Africa terrain tamer build? So a smart alternator can drop output to something like 8 or 9 volts, is there a scinario where by your starter battery can be fully charged in the eyes of the smart alternator however your aux batteries are near depleted and the dcdc charger pulls your starter battery down to a point where by it can no longer start your engine despite the alternator still effectively charging? My theory is the smart alternator should be smart enough to figure this out and fast enough/be able to provide enough amps to starter battery to cope.
Scinario 2 - your alternator becomes defective and cannot provide enough amps to keep your starter battery topped up, the dcdc charger will happily help kill the starter battery much quicker, this drops to a point where your vehicle electrics cannot run and your lose engine and all "factory" vehicle power. (It would happen anyway but the dcdc has made it happen much quicker. O.k. alternator failure isn't that common without warning and if it did happen your red dash charge light comes on so you can pull the dcdc fuse and potentially divert solar power to give the starter battery some form of charge - that would be pretty pointless in the U.K though, with our weather!
Perhaps I'm overthinking the perfect storm combination? I think I'm into my 6th or 7th year of unbroken patreon support for you Andrew. Keep doing what you are doing, we all get a great amount from your videos. I truly like the fact you are unbiased and not worried about saying the truth.
Do you have any future trips planned with Mr Paul Marsh? Stay safe and let's ride this storm out one way or another...
This is why I haven’t changed from my ‘old version’ SBI and use a mppt solar charger as well.
Has your powertech unit ever started constantly beeping at full charge?
Awesome video, I get it. I am also having another weird problem. After using the fridge for the day and I get back in and drive, my dash lights start coming on. I am sure this is the computer shutting things down for lack of power. Sometimes it is when I underrate. When the second battery if full there is never any problems. I have 120 series Prado 3lt desire. I have wonded about the Alternator but am now wondering about the dcdc charger. Any thoughts?
excellent vid, well explained. And very good to know.
Very interesting. I am working on upgrades to my Jeep and the dual battery setup and was going to get one of these.
What if you put a switch in the cabin to control when the charger is allowed to operate, normally it would be in the ON position so it can operate as per normal, but if you want to do work on the car with ignition on, for a period of time the switch will disable the charger, maybe a red flashing light also when it's "off" to warn you so you don't get to the destination and it's wasn't charging because you forgot to turn it back on ?
helpful, i have asked the victron guys if it would do this with the orion dc to dc charger
Can you use a relay that only activates the DC charger when ignition is on so the main is always isolated when engine is off?
Yes. Or there is an even simpler, cheaper, lighter solution: When changing externally, charge the start battery first.
could you put a redarc VSR in between starter and auxillary, that way the starter battery won't give juice to the aux?
does the dc dc charger not have an 'accessory power' input signal though? that would still be off and therefor isolate the batteries?
I see he mentioned the trigger cable. This is what i meant. If he had this trigger cable hooked up, it would have told the charger that the vehicle wasnt on, and therefor would have isolated the batteries regardless of the voltage on the start battery?
I run the trigger wire through a switch and to 12v+ that way I control when the DC-DC is on.
Hi i do similar ,plug into cig plug and works fine, cheers terry.
What happens when you use solar and the car is off
@@Nathansillav My solar batteries are separate from the vehicle, so it functions the same if the car is on or off.
Will this happen if you dc to dc has solar input?
Good point. I am about to install a redarc DC/DC into my jeep with an AGM and LiFePO4 auxillary battery and I have been looking for a AC battery charger to do what you are doing.
you could use ignition wire vs voltage sensing on the DCDC
Great lesson for us all, thanks Andrew
It means they are not such smart chargers after all. Have you brought this up with Redarc?
On an isolator setup redarc sbi12, charging both a start and dual purpose marine stoaway at the same time off a battery maintainer at 2amps. I have been separating them when stored in the shed would that be harmful with both on the one. Got a better 5amp victron one that would be easier to just plug into and do both. I know the isolator isn't as efficient but for a basic under bonnet setup that I wanted to be able to jump start myself it works good enough. Also add those large fuses are not the greatest usually the holders cannot stand up to the current, midi are far better and easier to store as spares
User-induced issue. There are many ways to do it correctly and one way to do it incorrectly (by triggering the dc-dc with a tiny mains charger on the starter side).
Either isolate when shore charging starter batt with a tiny mains charger or use a mains charger of the appropriate size. Or charge aux back from mains with a dc-dc that maintains starter batt.
Patient: it hurts when I do [this]!
Doctor: stop doing it and it won't hurt anymore.
Was kind-of aware of this but good to be told, probably could make a safety circuit for this but a Big Label on the charger will be the cheapest solution.
Connect the trigger wire through a relay. Pin 30 to key on power, 86 to key on power, pin 87a to dcdc trigger wire and 85 to alternator thin wire which grounds the battery warning on dash, so when alternator is working the DC DC will sense and turn on the charging.
I thought 85 was the ground side of the relay...
@@Michael_Mears Ah, yes.. I just noticed the mistake. Corrected it now.
Aah, good ol' relays ....I like this 👍🏿
hi andrew, mate where do you connect the negetive clip? battery of chassis???
Battery. Always the battery.
Hi Andrew, in your opinion, how can we avoid drain out the starter battery ? By not connecting the ACC wire(if not smart alternator)? or simply add a switch by the starter battery and switch it off if turn on ACC (engine offf)? So, if someone never leave the ACC 'on' whatever condition it is, the starter battery won't be fltten, it this correct? By different manufacturers, is your findings applies to all of them? (Renogy, Atempower, Redarc, Hisae, Projecta....)? What if there is a solar panel connected with 5-10A current presented? thanks !!
It could not be simpler . . Charge the auxiliary battery directly, and not via the start battery. Problem solved. It's that simple!
very interesting.. Once you know this it is easy to avoid but like you I would not have thought of it first
👏👏👏👏THANKYOU.
What about attaching the blue trigger wire to the alternators output wire? Just a guess.
I was looking at the Redarc wiring guide that indicates a resettable fuse should be used in the setup. Therefore to charge each of the batteries wouldn't you just break the fuse during the charging cycle and therefore only charge the one you want?
Any thinking man would.
How is starter battery connected to second battery?
Completely off topic, but what tyres are you planning to fit on the rig? Great video as always!
He's fitted Falken Wildpeak AT3W's (I think that's the code).
Porque não colocar um botão para activar/desativar o carregamento auxiliar?
I have a TS800 DC/DC converter which has a vibrationsensor to check if engine is running, works fine, also when ac charger is hooked up. Except on a long trip on a ferry where it completely drained the starter battery 🤔
Crazy. The auto-sensing circuit worked against you. Very informative. Thanks for the lesson.
It may be worth noting that every time you charge this way you are depleting the crank battery far too much even if you leave it on for the full cycle. It's being drained way down then recharged slowly, bad practice. Better to charge house batteries separately.
Yes, that's a better procedure / good practice.
J M or get a DC to DC with a more appropriate cutoff voltage if you can’t change it in the settings.
I installed a switchable circuit breaker between the main battery and the DC to DC charger to separate the two Systems if I needed to.
I did however learn the hard way about what you are talking about because I forgot to turn the switch off
So you are saying, when the engine is on, if the difference between the alternator output amps and draw from the main battery for various components are less than 50amps, still the main battery will discharge?
Good point, and correct. That’s why you need to match/balance all electrical equipment in your circuits. He said his alternator puts out 170A, so if all vehicle systems are using up to 120A maximum, then I guess he’s OK under alternator power. However, it sounds like it might be a contributing factor to his starter battery being drained. When he said he had a 50A dc-dc charger, I immediately thought that was overkill, unless his alternator can indeed keep up with total demands, and unless he has a bank of auxiliary batteries in the 200AH plus range. Very good point buddy.
That's a good heads up on protecting your starting battery especially these days because a lot of new cars run their computer systems of this battery. When the main battery is drained the system needs to be reset and then comes the hard part finding passwords. This would be a nightmare if your in the middle of nowhere without a dealer or a auto electrician around. Solving this problem for you was good,your able to know how to fix it. I think it's a good idea for any 4x4 driver to practice these scenarios just in case it does happen. For me if l bought a new 4x4 l would disconnect the battery at home to see what would happen to the system.😁👍
Passwords ?, the only thing that needs resetting on my 2019 Ranger is the Auto drivers window, it resorts back to non auto, everything else works fine after a battery disconnection just like any decent 4WD should be, as the ECU'S have self powered backups inside, if a 4WD is designed like you say, then I would stay away from it.
Sounds like these expensive systems have plenty of traps if not set up or used right. For now, I just have a really cheap set up of the main battery for all the original vehicle systems (1970s Land Rover, so very basic), and a second battery for accessories like power sockets, stereo, auxiliary lights, seat and screen heating and so on, any thing not essential to driving. They’re linked by a heavy relay which it triggered by the alternator diode pack (dash warning light terminal on the back of the alternator). It works very simply, so the batteries are isolated unless the alternator is providing a charge. I want to add solar for the auxiliary battery. The primary shouldn’t need it - main systems are drawing power if the vehicle isn’t being used, and in such an unlikely event, the engine could be started by jumping (a hard wired isolator connecting only for emergencies) from the auxiliary battery. There is a lot to be said for simplicity.
Just the man I wanted to ask a couple things. Can I safely charge my lithium auxiliary battery with a 20 amp AC/DC chargerdirectly if half depleted while my Redarc bcdc is connected without affecting the whole setup? Regards, Steve
no. Some Lithium battery sellers will tell you you can. But the voltages are not the same and while it will accept a charge direct from the alternator, it will and can never charge it properly or efficiently. But your Redarc BC-DC will charge it perfectly.
I have a Victron DC- DC on my two auxiliary batteries,with a 10amp smart charger connected direct. No problem with batterys, alwayes fully charged.
Overland Drive I use the same dual charger system for aux and main battery, just leave a shore line plugged in and both batteries are charged and maintained, easy. Worth buying a decent dual charger
Thank you Andrew, I always follow your channel with great interest and I particularly appreciate your willingness to share freely your knowledge and insights. I would be equally keen to hear expert opinion from Redarc on your observations. Presuming you have this would you share those with us too perhaps?
Carl Tunstall shame his information is often incorrect, omits important details or is a bias of his ignorance (take the ARB TPMS video for instance)
Here’s what Redarc said.... In regards to the connection of the blue trigger wire on BCDC, the following needs to apply:
1) If your vehicle has a standard alternator type (fixed voltage), the blue wire can be left disconnected
2) If your vehicle has a smart alternator type (temeprature compensating or variable voltage), the blue wire needs to be connected to an ignition source
3) If you are unsure of what alternator type you have, it is best to connect the blue wire to ignition
We have indeed seen the video mentioned and it does explain the connection of the blue wire, just not in great depth as to how it operates.
Andrew, I'm a bit confused, they dont look like 50A cables