Triple Battery Management

[relyimah]

Hi, it's been a hot minute since I've posted - hopefully some of you awesome people are still about?

I'm looking into options to have a triple-battery setup - starter, aux1 in car, and an Anderson plug to manage a battery in my camper trailer.

Wondering what the best setup is for this with a battery management system. Most of the ones I have found only seem to support two batteries, so not sure if there are options out there for three? Seems like it would be something that is pretty common to support 12V in a camper...

[Touses]

Hi bloke.
I have a triple battery system.
Lead acid starter for the 4.2.
105 amp AGM in a box under the ute deck, 10amp dc/dc charger on that.
Two 105 amp AGM in my back pack camper, 10 amp dc/dc charger on them.
What I did have to do was upgrade the alternator from std 80amp to 130 amp charge at idle.
The auto leccy waffled something about intelligent stuff that sends charge to the battery/ies that most need it.
My eyes glazed over early on, so don't understand/can't explain.
I am sure tho' that it works.
Have a chat to a leccy or google.

Cheers

[PeeBee]

I think you might be better served with an approach on a caravan camper site, however the solution has a number of variables I guess. I had a setup with Wet cell starter and large AGM bank in the back. I tried Strling Power Systems - expensive, marine focused and ratshit techncal backup or sales support when things failed during warranty period. I moved to CTEK , there was a 2 component system, expensive for what it was, was reliable though, and handled the charge fine unlit an act of stupidity on my behalf blew it up. The different battery types were not an issue, and similarly the AGM in the car and in the caravan is simply a plug.
I now run an Optima AGN crank and lithium bank in the rear. I use Renogy for the lithium, with the feed coming off the Optima. The Alternator is upgraded from 130amp to 300amp. The most I have seen the alternator charging at is 190amps. The Renogy has a program that wont start charging the Lithium until the float voltage in the AGM is achieved, so no flat crank battery - from what I see the charge to the Lithium bank starts within 10 mins for first start of the day. I use Victron for the solar controller but the Renogy will do that as well, so I have redundancy. The Renogy units are the only ones I can find that can do a 2 x 60 amp charge in parallel - no one else makes one - there is a problem around two units fighting each other and they will blow up if you dont get the parallel capability if you need a chrge above 60amp.
The renogy chare rate is 60amp per unit, works well. The Renogy uniy was around $250 and their technical backup is great I have found. So I use the voltage regulator to do its job on the Optima, then the Renogy confirms when it will start bleeding off to the lithiums, which then causes the Alternator to lift to the initial 120amps charge - its pretty simple, dont forget your in-line fuses and mechanical protection of cables and do a volt drop chck to ensure you run the right size charge cables, DC low voltage is a nightmare. Hope this helps.

EDit the different battery types will be a problem if you try to charge each type at the same time, but if the set up is piggy backed off the starter, then the charge controller would look after the AGMs independently and the alternator the crank wet cell

[relyimah]

Thanks Touses and PeeBee,

So what I think I am hearing is that there isn't really a 'good' option for a single BMS for all three batteries, and the 'better' approach is to have a standard BMS for my Starter/In-car Aux, and then a second simpler isolator for my Aux in the trailer?

* Starter => BMS => Aux1 => Andersen => Trailer => BMS/simpler => Aux2

Expect this way, I'm still charging off my Aux only once it's topped up fully, and can still use the Andersen plug for other things from my Aux1...

I'll definitely check in with an auto elec., as this will not be in my Patrol, but a newer Ford Ranger, so I expect there will be some level of "Smart" charging involved (I just prefer advice from people that actually work on "real" cars hehe)

[PeeBee]

Thanks Touses and PeeBee,

So what I think I am hearing is that there isn't really a 'good' option for a single BMS for all three batteries, and the 'better' approach is to have a standard BMS for my Starter/In-car Aux, and then a second simpler isolator for my Aux in the trailer?

* Starter => BMS => Aux1 => Andersen => Trailer => BMS/simpler => Aux2

Expect this way, I'm still charging off my Aux only once it's topped up fully, and can still use the Andersen plug for other things from my Aux1...

I'll definitely check in with an auto elec., as this will not be in my Patrol, but a newer Ford Ranger, so I expect there will be some level of "Smart" charging involved (I just prefer advice from people that actually work on "real" cars hehe)

You wont find a smart bms that will handle wet and agm - or at least not that i know of. Even a battery charger requires a specific algorithm for each charge type. There are numerous smart chargers out there. You may find there is minimal difference in voltage between wet and agm and get away with a single one, just depends if you want to shorten the life of the batteries by either under or over charging one type over the other.