GU 2nd battery

Submitted: Tuesday, May 16, 2006 at 16:20
ThreadID: 33943 Views:1809 Replies:7 FollowUps:1
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Hi all,
I installed a 2nd battery on the weekend and now have to figure what wires to connect to the backup battery. Do I need to rewire every thing or is there some magic trick by intercepting some of the fuse wiring. I am really just wanting the trailer connection (with electronic brakes) and the cigarette lighter plugs (front & back ) connected. Anybody help me out with some easy ideas on the the way to go?
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Reply By: hl - Tuesday, May 16, 2006 at 16:55

Tuesday, May 16, 2006 at 16:55
That would be pretty messy.
It makes more sense to install one or more seperate power outlets (fused).
AnswerID: 172967

Reply By: brian - Tuesday, May 16, 2006 at 17:19

Tuesday, May 16, 2006 at 17:19
Do you have either an electronic or manual isolator fitted or are the batteries in parallel ?Why do you want trailer connected to 2nd battery ?
AnswerID: 172971

Reply By: The Fox - Tuesday, May 16, 2006 at 17:28

Tuesday, May 16, 2006 at 17:28
Leave the electric brake circuit alone - no need to run that of the 2nd battery.

I concur with previous response - you are better of to run separate fused (or circuit breakers) power cicuits. Anything you are likely to run of the front cigarette lighter is unlikely to draw any significant power any way.

If you are going to run a fridge in the rear or in the trailer, you should be running bigger cable than what is probably installed anyway.

Buy good quality, large twin core cable.

If using a fridge and wanting a long term, good quality job, don't use a cigarette lighter outlet. Either Engels proper outlet or 2 pin outlets from an electrical wholesaler are good.

I presume you have fitted an appropriate isolator between the 2 batteries?

AnswerID: 172972

Reply By: Member - Roachie (SA) - Tuesday, May 16, 2006 at 17:28

Tuesday, May 16, 2006 at 17:28
In my case I have the 2 batteries separated by a basic solenoid. The switching of this can either be done automatically by using the wiper motor POS wire, or (as I have done), use a manual switch so that YOU can control when the 2 batteries are connected.

I know that wasn't part of your question, but I said it anyway cos it makes me feel better ;-)))

Now, as for the things you want to power-up with the 2nd battery???? I would suggest you buy a Narva fuse block (they come in various sizes from 4 to 12 I believe). I use a 6 fuse style and drilled-out the small holes in the 6 tabs on one side to 1/16". I then stipped about 3" of the insulation from one end of a length of cable. Use the largest size cable you can find that will fit through the 1/16" holes in the fuse block. Solder the wire at each tab and mount somewhere convenient (like the firewall), preferrably with a portion of a plastic ice-cream container lid or similar between the fuse block and the firewall as extra insulation to stop short circuits......this is a job i have not yet got around to after only 5 years of owing my GU).

You can then run separate wires to various accessories like fridge, trailer plug etc.

However, I wouldn't be changing around the factory-fitted plugs and accessories or mucking around with the power for the trailer brakes. Leave these as they are in my opinion. Instead, instal separate Hella plugs (or ordinary cigi plugs) in the cargo area and possible one (or more) in the front as well. If you are powering a Engel fridge, use the screw-in plug they provide as an accessory. Always use the largest feasible size cable you can get hold of....say 6mm as a minimum.

What accessories do you intend to power on the trailer? If you have another battery back there, then you should be running very heavy cable through an Anderson plug.

there are many facets to your question and I have only touched the tip of the ice-berg.


AnswerID: 172973

Reply By: Derek from Affordable Batteries & Radiators - Wednesday, May 17, 2006 at 07:02

Wednesday, May 17, 2006 at 07:02
Hi Fred

Read the Battery Article and give me a ring if you need a bit of advice.

Regards Derek.
AnswerID: 173073

Reply By: Member - andrew B (WA) - Wednesday, May 17, 2006 at 12:20

Wednesday, May 17, 2006 at 12:20
Just a bit of a query - sorry about the hi-jack. With all of the heavy cable required to go from the under bonnet to the back of a wagon or trailer, is another option to put another battery (small will do) close to the applience. It is my understanding that the small wires will still carry the volts, but the volt drop is caused by a large amperage draw. If there is a small 12 volt battery near the applience, it would provide the higher amperage for say the fridge compressor to start up, and the amperage draw on the under bonnet battery would be much lower over an extended periond of time.

I hope one of the battery guru's out ther can translate what I am saying here. This sort of system works well on a mate's boat where he runs a fairly light wire to a 4th battery which runs his anchor winch

Cheers Andrew

AnswerID: 173123

Reply By: Member - Fred L (NSW) - Wednesday, May 17, 2006 at 13:47

Wednesday, May 17, 2006 at 13:47
Great help - thanks to everyone. I have the two batteries totally seperated and charged through a 'smart solenied' see article referred to by Derek from ABR.

My problem is that I always seem to do easy jobs with great difficulty rather than difficult jobs easily.

For your info I just want to power the front cig outlets so I can have the uhf radio and other appliances on at any time without havinh the ignition on - the back outlet to run the Waeco and the CT outlet to run the goodies in the trailer when the CT battery runs low. I guess it comes down to want Roachie said (thanks) - and run new cables. I just hope I don't end up with any dust holes in innapropriate places.
AnswerID: 173141

Follow Up By: Member - andrew B (WA) - Wednesday, May 17, 2006 at 15:19

Wednesday, May 17, 2006 at 15:19
I recently ran new wires in my GU to the console etc. It was quite easy to remove the section around the gear levers and ciggie holder to get access. I left the origional ciggie lighter alone and fitted another plug to the opposite side in front of the transfer lever. There was a small black panel blanking off a hole where a switch may be on the Ti model, so I just drilled a hole in to mount the new socket. It looks like a factory fitment. You could draw power from here for your UHF.

I also ran another wire back to the rear of the centre console (haven't fitted the socket yet), and 2 more wires back to the rearleft, and installed two sockets in the small panel that you can remove. The wires were all drawn through the existing rubber boot to the engine bay about where the passenger's left foot is. I had to make a begger hole in this boot, but a good dollup of silicone solves any dust/water problems.

Good luck with it all

Cheers Andrew
FollowupID: 428979

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