Auxiliary Battery Wiring

I have installed a 2nd battery in my GUIV patrol with a Redarc Isolater and have checked that the Redarc is opening and closing at the correct voltages. I then rewired the rear power socket with a new +ve wire direct from the aux. battery after disconnecting the original +ve wire and removing the original fuse in the fuse box. I left the original earth wire in place at the power socket.

I have found that running an Engel fridge for 2 days from the rear power socket while camped, without running the motor, resulted in the starting battery going flat, as well as the aux. The Redarc was opened all the time.

Sounds like there is some voltage leaking from the starting battery into the aux. circuit somehow.

Can someone offer some advice on this please.

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Reply By: ABR - SIDEWINDER - Wednesday, Mar 04, 2009 at 21:37

Wednesday, Mar 04, 2009 at 21:37
Hi Brian

What else is connected to the aux battery ?

Was the Redarc 'off' ?

Was the Redarc 'warm' ?

You may have a drain via a few items...

Spotlight relay, 2 way radio, brake controller, radio memory function, trailer plug.

I would also be worried if an Engel flattened both the aux and main batteries in just 2 days. There must be a big drain somewhere. Would suggest and amp test using a multimeter.


Derek from ABR

AnswerID: 352223

Reply By: Member - Graham H (QLD) - Wednesday, Mar 04, 2009 at 21:41

Wednesday, Mar 04, 2009 at 21:41
Are you sure you have the batteries connected to the correct terminals on the Redarc. Easy to hook them up around the wrong way That would run the start battery flat.
If I remember rightly the little black box goes up if the terminals are mounted 1 above the other say on the inner guard. And the start battery goes on the top one.
Easy way to check is turn the lights on full for 10 mins and see which one drops voltage.
Hope you put a fuse in the new wire and used at least a 6mm2 wire and an equal weight neg Not much good having one smaller than the other

Too wet to go out and check mine tonite.


AnswerID: 352226

Reply By: Hairy (NT) - Thursday, Mar 05, 2009 at 01:02

Thursday, Mar 05, 2009 at 01:02
A mate had a similar problem a while ago and we stuffed around for a couple of days trying to work it out........Problem is I cant remember exactly what it was. BUT.....
I think what his come down to was a crap earth?....It wasn't so much loosing charge but never getting enough to start.
The earth tested fine but when we put the multimeter directly on the battery it was heaps better???
I think we put it down to, and then heard latter that Nissan's had a problem with using an earth off the engine rather than a good clean earth off the body.????
Sorry...cant remember exactly what it was but if no one gives you anything better to try ...Ill find out.

AnswerID: 352251

Follow Up By: Member - Peter R (QLD) - Thursday, Mar 05, 2009 at 08:36

Thursday, Mar 05, 2009 at 08:36
It could be that the Redarc is one of the old models that did not permit charging of the 2nd battery
Read page 4 of the Redarc newsletter

FollowupID: 620490

Reply By: Maîneÿ [wa] - Thursday, Mar 05, 2009 at 09:51

Thursday, Mar 05, 2009 at 09:51
you say "have checked the Redarc is opening and closing at the correct voltages" so no problems exist that can be associated with the fitting and/or working of the Redarc isolator ??

You say the problem is ""the starting battery going flat, as well as the auxiliary battery"" this does indicate the two batteries are still (somehow) connected in some way, if the Redarc was separating the two batteries there is no way the original cranking battery would loose power that can be attributed direct to the Engal fridge, because the battery isolator is the only direct connection between the two batteries.

Small voltage drop associated with things like radio's and interior lights may also contribute to the power loss in the cranking battery, this is not associated with the fridge and will be lost even when the fridge is NOT connected, so you would see it daily, not only when the fridge is connected.

My suggestion: recheck the battery isolator is working correctly !!

Mainey . . .
AnswerID: 352278

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