Running a 2nd battery in a car?

Post by **lewd lude lover** » Fri Jul 06, 2012 9:33 pm

score.

vti2003 · Post by **vti2003** » Fri Jul 06, 2012 9:49 pm

I am trying to remember how I did this on my VW Campers - I did it backwards somehow! I wired it in such a way that the main batteries always powered everything but there was a backup battery that enabled starting if the others ran flat.

I "think" I used a split charger relay, left everything running of the main battery (I had two main batteries in one van) and wired a fused switched feed from the backup battery to the aternator input in the relay.

The end result was that no wiring in the van was changed but in the event of a flat battery you could flick the switch to bring the backup battery online via the relay as the relay was being operated by the power in the backup battery. Does that make any sense????

At the time is seemed much easier than rewiring headunit, lighter, internal lights etc to backup battery.

Post by **Ammo** » Fri Jul 06, 2012 9:58 pm

Yeah that would work but I've got a leisure deep cycle battery for the car (the Lude actually uses one as it's main battery as well, it was free) so i'd rather flatten the deep cycle than the starter battery.

Other problem I've thought of as the battery needs to be vented and I need all the space i can in the back, where the hell am I gonna put the 2nd battery lol

Post by **4thgenphil** » Fri Jul 06, 2012 9:59 pm

Post by **Ammo** » Fri Jul 06, 2012 10:06 pm

I do have a roof rack for it already but I don't think that would work in our British summer

'92 Si VTEC · Post by **jjmartin349571** » Fri Jul 06, 2012 11:20 pm

Ditch the spare wheel, stick it down in there? Could even drill a hole and run tubing out the floor to vent battery gas. You could even go nuts and turn the spare wheel well into a cubbyhole

this does mean losing the spare, could be problematic for MOT unless you get the spray stuff. Or if you wanted to go really individual, get the spare wheel holder off an old landy, and have the spare wheel on the boot

Post by **lewd lude lover** » Sat Jul 07, 2012 12:19 am

put it in a bin bag. iv run festivals on electrics tied inside black bags

kernow_lude · Post by **kernow_lude** » Sat Jul 07, 2012 8:40 am

Yes, the leisure battery is separate from the starter battery
run your radio / amps / cig lighter off the new battery. when the leisure battery runs flat, just start the car (this will start off the old car battery.)
Just remember to FUSE any cables you take from the leisure battery 10amp for cig, 20 for radio 30 + for amps

Another thing that cool is if you have a flat battery on the main car (like you left your lights on), you can give your self a jump start

(using proper jump leads)

you could fit a two way toggle switch.

cut radio acc power supply at back of radio
wire from radio to MIDDLE pin
original wire going to radio to one outer pin
New wire (Fused next to battery) run though the car to the other pin.

that way you can have the radio turn on;off with the ignition or flick the toggle and its now on all the time.

Post by **Ammo** » Sat Jul 07, 2012 3:15 pm

Just had a thought, the car's got a Towbar with twin electric sockets

Am I right in thinking that the grey socket will charge a caravans battery, so all I need to do is hook into that wiring and I've already got the split charging system in place?

vti2003 · Post by **vti2003** » Sat Jul 07, 2012 3:51 pm

Probably. Just check the pins with a meter