Thread: Dual Batteries

Originally Posted by CraigE

With the single main wire set up in the Defender what are the options to get the accessories to run off the deep cycle battery. The way it seems to be set up is everything seems to come off the main power wire from the starting battery. I am led to belive that this needs to be fed off the cranking battery to start the vehicle. Is there any way to get the accessories fed off the deep cycle battery easily without having to rewire everything? Is it just a matter of putting the terminal opposite way around on the 2 batteries or will this stop the cranking for the starter?
Thanks

The way I did it was to get a Traxide DBS. You join the two batteries by a common earth (easy in a defender). The traxide unit manages the connections to the two batteries. Then just hang your accessories of the secondary battery.

Have a look in the Projects and Tutorials, there are a number of pictures in there of various setups.

I am more talking about standard car accessories already in the car fuse box like stereo, etc not add ons, so that the cranking battery is for just that only.
Cheers

Thanks for the plug Captain.

Hi CraigE, what sort of accessories are you running off the main battery now and what do you mean by having to rewire everything as it should be pretty straightforward in a defender.

Cheers.

Are you wanting to feed things such as radio, heater/AC fans, lights from the second battery? Why? Perhaps the radio would be OK, but I really feel any normal car electrics would be better left running from the main starting battery.

You would need to intercept the various feeds to the fuse box, and this would be a tricky job, best left to an auto-electrician.

Most of us seem to want to keep the 2nd battery for a fridge, camping lighting etc., although I have seen advice that a winch is best powered from the main battery. (Don't have one myself, so I am not an expert on winches.)

Cheers,

Lionel

Yeah, Just a thought. Will have a good look this break. The way the car is wired most power for things like interior lights, stereo, alarm, central locking, headlights, spotlights etc comes off the cranking battery. just thought it may be better to distribute the load a bit better. The fridge and GPO is the only things that really come of the deep cycle battery. I think some other things have been fed into the spare feeds on the fuse box like the invertor (will look at moving that directly off the deep cycle maybe). Have had a couple of flat cranking battery issues lately. Will try one thing at a time. Even though the deep cycle will start the fender I dont think it is good for it. Would rather drain the deep cycle and make sure the cranking battery is kept charged.

Hi CraigE, sorry, I didn’t read your post properly and I totally agree with Lionel’s post, unless you have some specific reason, leave the vehicle original accessories where they are because most are only used while the motor is running and as such, do not draw any power from the cranking battery.

As for things like the inverter, most definitely move the inverter to the auxiliary battery. This one device, depending on the inverter’s size, if left on, can pull a few amps even when they are not providing any ac power.

What are you planning to do about separating the cranking battery and auxiliary battery once the motor is off.

One more point, starting the vehicle off the deep cycle battery once every so often should not effect the battery but don’t make a habit of it.

Cheers

Drivesafe,
I have a Carlee (TJM) dual battery system on it that has been on the Disco, Rangie now the Fender otherwise I would have one of yours. I think you are right and it is the invertor that may be causing the issue, may set it up through an ignition source so it only runs when the car ignition is on or through the deep cycle battery.
Cheers