Triple battery setup run down.

[mudski]

So I have been searching our forum for triple battery setup's. As we get our camper in a few weeks and need to prepare the car...Read a fair bit but just want to ask to make sure I have it correct as per my current setup of what I have.
I have the cranking battery, connecting to the 105AH deep cycle aux battery via a Redarc SBI12 isolator.
Is it best to run the cable down the back of the car from the cranking battery or the auxiliary battery? I was first under the assumption its from the cranking battery, then I found a thread where it was from the auxiliary battery.
I have some 6B&S cable here I will use....

Cheers.

[MudRunnerTD]

Yeah I would think that it would come from the aux battery or split direct from the redarc. I have mine from the redarc to an Anderson plug at the rear.

My logic is that your battery management system (redarc) is designed to manage your cranking battery first as the primary battery then your aux battery or batteries once your primary is fully charged.

[BigRAWesty]

Will you be running a charger for both batteries?
If so run both of the cranking battery so the are both drawing raw voltage Off the alternator once the main cranking battery has charged.
But if you intend in running the trailer battery and aux battery off the same charger the run your cable from either the charger or the aux battery.

Any solar in the mix?
Also 6b&s?? What size mm is that?

[mudski]

Yeah I have got 180w solar panels for when we set up camp but will be selling them with the AGM I have now as firstly the panels are huge, too big to carry and second, the trailer comes with a battery fitted so I don't really need it anyhow. Pity, as I only bought it before easter and used it once...

Is your 3rd got a charger like your second? If so I'd go cracking battery.
If you go the 1st aux battvery then your 3rd has to wait for cranking to charge and then the 1st aux to charge before getting anything.
If On cracking then both aux batteries will charge at the same time.
But also your not wasting voltage. Your aux is already regulated by the first redarc, so charging 3rd will be slower again.

If not the as MR, run both from the redarc charger..

That's my theory.. Cuppa will probably disagree but he's been doing it longer than me...
Any solar in the mix?
Also 6b&s?? What size mm is that?

The third is the trailer battery Kallen. So now I have only two, one cranking and one aux battery. So I will have three all up in the end. Going by your first sentence it looks like you think I already have two aux batteries and are looking to instal a third???

[mudski]

Also 6b&s?? What size mm is that?

14 mm squared
stranding 168/0.32
6 gauge
125 amp rated

[MudRunnerTD]

Yeah I have got 180w solar panels for when we set up camp but will be selling them with the AGM I have now as firstly the panels are huge, too big to carry and second, the trailer comes with a battery fitted so I don't really need it anyhow. Pity, as I only bought it before easter and used it once...

Hey mudski when your ready I'd be interested in some details of your solar setup mate, might be interested.....maybe.

[BigRAWesty]

I got a bit confusing hay.
I'll change it to make it more understandable... Lol night shift...

I'd also run an isolator on the trailer line. So when it's not connected you can safely terminate the power from the rear of the car and eliminate any chance of a short..

[mudski]

Hey mudski when your ready I'd be interested in some details of your solar setup mate, might be interested.....maybe.

Its 3 80w panels that fold up, I have change the crappy reg that was on it to a Suntrans 20a reg and also change the 10m lead from the reg to the battery clips using 6 B&S cable.
I'll have to find the specs on the panels if you want more info....

I got a bit confusing hay.
I'll change it to make it more understandable... Lol night shift...

I'd also run an isolator on the trailer line. So when it's not connected you can safely terminate the power from the rear of the car and eliminate any chance of a short..

Good point there....

[Cuppa]

"That's my theory.. Cuppa will probably disagree but he's been doing it longer than me... "

Half.
I would connect the trailer battery to the crank battery, & because it is way back in the trailer I wouldn't use an isolator like the SBI12, instead I would use a DC to DC charger. 6B&S is good, but with length & connections there is still a possibility of resistance/voltage drop. A DC to DC charger will take care of this if mounted near the battery in the trailer. A second SBI12 would work, but not very efficiently compared to a dc to dc charger. (The SBI12 only allows for standard alternator charging which will only seethe trailer battery charged to about 70% capacity ).

The SBI12 does not regulate anything, nor is it a 'charger'. It is basically a voltage controlled on/of switch to prevent the crank battery being inadvertantly flattened. A DC to DC charger will regulate the charge boosting the voltage if necessary to ensure that optimum charging from the available source (crank battery) will occur ensuring the trailer battery is charged to 100% capacity. This also assists if their is any voltage drop from the length of cable/connectors.It also functions as a 'crank battery protector' like the SBI12. Whilst an aux battery under the bonnet, used primarily for winching with the motor running, or small loads can get by with only being charged to 70%(ish), a battery in the trailer used to run a fridge while camping, without running the vehicle really needs to be fully charged, or you will find that you either have less running time than you would like, or you will end up prematurely murdering your battery through over discharging it. Whilst a dc to dc charger costs a bit more to buy than a Voltage Sensitive Relay (VSR) like the SBI12, in the longer term it will save you money (batteries aren't cheap) as well as making camp life a bit easier. VSR's have become largely superseded these days.

Cuppa

[megatexture]

I've got mine much like you are describing only I have a crank and aux on the car and two aux on the camper, both on the trailer bum off the aux batt on the car via Anderson plug and I've never had an issue. I've also got a 120w panel for longer stays with plans to purchase a second 120w

Edit:I use a ctek 250 dual on the car