Isolator wiring for GU Patrol charge and glow circuits

Submitted: Monday, Mar 14, 2005 at 09:17
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I installed a Redarc isolator into my GU patrol using battery/starter cable for the connections and put the optional remote switch and LED indicator in the dash. It all works well, I think!! The Redarc fits neatly under the battery breather for the main battery.

There was two connections at the main battery originally which generally appear to be one for the 'starter' and one for the 'accessories'. I connected the 'accesories' loom directly to the aux battery side of the Redarc so that the radio, interior and exterior lights etc all run from that. Unfortunately the Glow plugs also run of this loom so they are on the aux battery also. I can live with that as a push of the button will activate them if really required.

I want to confirm which loom the charge goes into as standard. I thought it was into the start loom but now I am not so sure. Can anybody provide this information?

If the charge does go into the 'accessories' loom then I will have to rethink what I have done. Thanks in advance for any comments

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Reply By: muzzimbidgie - Monday, Mar 14, 2005 at 17:36

Monday, Mar 14, 2005 at 17:36
Jamie. When my redarc was wired up, we ran a new cable from the starting battery to the redarc, and then to the aux battery. Yes the radio runs off the main battery, but this would be easy to change once you locate the power at the back of the radio. Any additional power needed (UHF, fridge, compressor, lights etc;) gets put straight into the aux wiring at the back of the car. Also on your accessories wiring is the elec windows, central locking and alarm system. All of which, personally, I would want running off the main battery, as it was intended.
AnswerID: 102384

Follow Up By: Member - Jeff M (WA) - Monday, Mar 14, 2005 at 19:17

Monday, Mar 14, 2005 at 19:17
An even easier way is to lift the cover off your under bonnet fuse box, find the fuse for "DOME" which covers all your interier lights, cigerette lighter, stereo etc etc etc and remove the blade fuse. Then crip a standard blade type automotive crimp to a wire and slot it in instead of the fuse (obviously to the side that goes to the accessories not the bat). They fit perfectly, then run your wire either through a fuse direct to the aux battery or to an auxilery fuse box (if you have one).

That way you can then connect both the accessories, ecu, glow and starter all to the main battery and still have all your other gear running from the aux battery. Great for when you leave the interior lights on all night etc.

You can then put a switch on the radio so that you can turn it on without requiring "ACC" on or switch it back so it turns off with the keys out for round town.

Hope it all makes sense.... It's really very easy, it just sounds confusing.
FollowupID: 360144

Follow Up By: JamieMac - Monday, Mar 14, 2005 at 21:03

Monday, Mar 14, 2005 at 21:03
Muz, had not really thought about all the other stuff hanging off the Aux battery in my method of wiring. I supose I can live with losing most of the stuff you mentioned if the Aux bat goes down in a screaming heap as access to the kar with the key is always an option. Not sure if the lack of remote locking will prevent the car from starting? Anothe issue is that the lights will not be supplied by the alternator until the Redarc is happy with the start battery charge, could be a problem in the dark.

Will have a look at your idea Jeff, sounds good but did you do this on a GU? Will the std blade crimp fittings work with the mini blade fuses? If not I am sure I can find a method that does work.

It all looked too simple when I started and I am keen to get as much out of the aux battery as I can. Although I would prefer the glow plugs off the start battery obviously. I can rig a wire from the alternator to the start battery if required but first I need to confirm where it goes now. Its hard to see without opening up all of the looms floating around the engine bay. Not like the old days where a couple of wires was all you had to contend with; where they went and what they did could easilly be determined.

thanks for the input

FollowupID: 360152

Follow Up By: Member - Jeff M (WA) - Tuesday, Mar 15, 2005 at 14:35

Tuesday, Mar 15, 2005 at 14:35
I've got a mate who has supposadly done the same with his 2001 GU, I guess if they a mini blades you may need to trim the connector a bit. Should still work fine.

Mine runs from the main fuse box to my auxilery fuse box (which is mounted next to the primary). All other accesories run from there.
FollowupID: 360216

Reply By: Member - muzzgit - Tuesday, Mar 15, 2005 at 00:56

Tuesday, Mar 15, 2005 at 00:56
I have a feeling you could open youself up to problems doing what I think you are saying you want to do.

I don't think a GU will start if you simply run a wire to the starter. All new Nissans, petrol or diesel (except 4.2, for now !) require a good current to the ECU and fuel pump to start.

The main reason for a dual battery, as you know, is to be able to run a fridge and lights all night without the risk of having a dead starting battery. All the bits and bobs associated with getting started should be left connected to THAT battery (IMHO). You can run the auxilliary battery down every night if you wish, and it will always start.

When camping, we turn off all interior lights and use small fluro's hooked into the aux battery. Apart from all the other possibilties, alarm systems do not like a lack of power.

The stereo is the only thing hard wired in the car that I have considered rewiring to the aux battery, but up until now, we have opted to listen to nature more often than not. On the few occasions we have had a CD on for a few ours, this has never been anywhere near enough to drain the starting battery.

But back to your original question. Because the alternator is linked directly to your battery, all connections will get an equal amount of current (charge) if they are connected to the same battery terminal.

AnswerID: 102466

Follow Up By: JamieMac - Tuesday, Mar 15, 2005 at 08:20

Tuesday, Mar 15, 2005 at 08:20
Thanks Muzzgit

I would not run a wire to the starter but a charge wire from the alternator to the start battery. That way I can ensure it is the one being charged charged first, it is being monitored by the Readarc at the moment so it is pointless if the aux battery is receiving charge. In this situation the isolator will never activate to connect the two batteries together. I suspect this may be what is happening now.

How long does it typically take for the isolator to activate after starting the car??

As for the ECU and fuel pump I am not sure as the engine is still pretty basic and I think these are mechanical bits and on that basis alone would be enough to get it going. I managed to push/roll start my old GQ several times so I suspect these bits are not too reliant on electricity in the 4.2. The glow plugs are another matter though!!

I still fancy the idea (but not at any expense) of having anything not required to start the engine hanging off the Aux battery. I know radios and interior lights are not too big an issue but if the headlights run off the Aux it could prevent a problem or two.

Might have to run an Aux bus into the cab and put the relevant bits onto it if Jeffs method above is not practical. Would not really have considered all this if there was not two looms in the first place - Must be the trouble with too many choices!

FollowupID: 360187

Reply By: Member - muzzgit - Thursday, Mar 17, 2005 at 00:59

Thursday, Mar 17, 2005 at 00:59
I was not aware that your car was the 4.2, so of course you don't have ECU and fuel pump that need power. I shouldn't have assumed any differently. Sorry about that.

While I don't understand why you would want to run everything but the starter off your main battery, you have just answered your own question about charging the starting battery.

The redarc WILL NOT introduce the aux battery untill the starting battery has reached 13.5 volts. Only then will it cut-in to connect the aux battery. This is the sole purpose of the redarc isolator. When I start my GU 3.0 TDi, the redarc usually cuts in about 15 seconds after start up, unless I have been using the stereo and have left the doors open for a while, in which case it can take up to 2 minutes, unless I increase the RPM by driving or reving the engine. Only when the starting battery is at optimum charge will the redarc allow any charge to the aux battery.

For me, this is the best possible system to have. I have had several 4WD's with different systems, and the redarc is by far the simplest and most fool proof of all.

When we go camping for 2 or 3 days, we sleep in the back of the Patrol, and all power for lights and the waeco run off the aux battery. When driving home, sometimes we stop to inflate the tyres. Quite often the compressor will not run at full speed if I turn of the motor. Because the aux battery has not recovered from running the fridge and lights for 3 days, and the redarc automatically seperates the two batteries if the starting battery gets below 12.5 volts. But the most important thing is, the car will always start. And thats all I do to get the compressor running at full speed, start the car.

This for me is a must. If we lose power to the fridge or lights because the aux battery is dead, at least we can get going. The redarc will not allow a dead battery to drain a full starting battery.

If you run too much off the aux battery, you will simply be shortening the length of time you will have power. The only instance I can think of when you would want to keep the two batteries connected, no matter what, is using a winch. But you must always keep the motor running, otherwise your upbleepcreek.

I hope I havn't bored you to death, but thats my speel on it anyway.


AnswerID: 102744

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