Second battery relocation

[Irish]

Hey guys,

I'm relocating my second battery to the boot on my Mav. Just wondering what the correct thickness cable is to use? I was going to go 4AWG, as thats the thickest SCA have, but should I be looking at thicker?

It'll be running off a Piranha dual battery system.

Also, for the accessories themselves, I was going to run a junction box in the engine bay plumbed into the + cable going from the piranha unit to the battery. All accessories will be fused etc. Will this work reliably? or am I going to start popping stuff?

Any advice greatfully accepted.

[MudRunnerTD]

The fuse box will work fine. Your basically using the second battery but hooking into the supply end of it. If the car is turned off it will use he second battery.

I'm a if fan if bigger is better. Depends what your going to be running off the battery in the back? Your Alternator can supply between 70smps and 120ampdeprmfkng on your Alternator do you want the cable to handle the supply load of the Alternator. IMO. Make sure you also use the same size earth strap from the rear battery. Connect to your chassis and add another earth from your cranked the same size connected to the chassis.

[MudRunnerTD]

Make sure it's a Sealed GEL battery obviously.

[Irish]

Make sure it's a Sealed GEL battery obviously.

It won't be, but I'll be making up a fully sealed box for it venting to exterior atmosphere.

[MudRunnerTD]

It won't be, but I'll be making up a fully sealed box for it venting to exterior atmosphere.

It would be far far better to buy an AGM or GEL Battery mate. Then you can mount it laying over or whatever you need. Also, Matty had a battery EXPLODE in the back of his car last year mate!! While driving on an NP.com Trip! Lucky his little girl was not in the back seat or it would have been a disaster! Was a train wreck anyway but no kids involved.

[the evil twin]

There is no point having humungous cable to a rear battery unless you want to winch off it.
If you want to winch off it then putting it in the rear is a tad silly in normal circumstances.
If you want to parallel start off it then it will do the job nicely off 4AWG or even a tad lighter

There is also no point having humungous wire if the limiting factory is the Isolator current rating

A standardish battery will never accept the full Alternator output when charging.
To swallow 70 amps you are talking like maybe a 200 AH dead flat battery.
If you are locating in the rear for aux purposes you are better off using lower amperage wire and a DC/DC manager.

I have batteries at either end of my Ute and a Redarc because I winch from either end
Even so the interconnection is 4 AWG and it works OK for me

I also concur with the comments above regarding use of a Gel battery.
In a catastrophic failure they will split rather than explode.
In one of my GQ's I had my aux battery in the footwell of what would normally be the third row pax.
Again, works great but I would NEVER put anything other than a Gel battery in there

[Hodge]

I'd like to do this sometime in the future on my car. My current AGM is up the front together with the Redarc BCDC1240. As all my accessories ran off the secondary battery are at the back, it's pointless having the battery being cooked by the turbo up the front.

ET. Would you put the Redarc at the back closer to the secondary battery or leave it up the front closer to the main battery and run a cable to the rear battery from there? Would it make any difference?

[the evil twin]

Hi mate...

Rule of thumb is
Isolator (Redarc SBI, Piranha etc) - as close to the Cranker as practicable
Converter (Redarc BCDC, Ctek etc) - as close to the Aux as practicable

[Bloodyaussie]

It won't be, but I'll be making up a fully sealed box for it venting to exterior atmosphere.

Peter come and see me mate if you do want a different battery as thats one other great discount i get in the caravan trade.. think i paid $100 for my last 105ah .

[Irish]

Maybe I'll retask the deep cycle to run the motor I'll be putting in for my front gate when I finish it.

Thanks for the advice guys.

Evil twin, a rear mounted winch is actually on the cards in the future.

Thanks BA, will have to swing by then, thats bloody cheap.

[Bloodyaussie]

That price is for a acid deep cycle. .. ill get a price for a agm or the like during the week.