Dual battery system on 100's V8

Submitted: Friday, Nov 28, 2003 at 17:52
ThreadID: 8829 Views:2413 Replies:5 FollowUps:2
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Hi there, I know this ia a very much asked question, but has anybody fitted dual battery syatem to a 03 100's V8?? I have been getting conflicting reports from auto electricians. It nearly seems easier to fit a 3 position marine battery switch and manually set the battery that you want to charge. But can this effect the computers on board? Also any advice on driving lights please. Some say Hella others say something else. Thanks once again for your help
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Reply By: koh - Friday, Nov 28, 2003 at 21:09

Friday, Nov 28, 2003 at 21:09
Hi Andrew

I have a 03 V8 and fitted a duel battery system in it… I did it my self and all I have is an Optima marine battery as number 2 with an isolator between the two and made up a bracket to put he 2nd bat in . I have all the acc on the second bat excluding the radios. Put the switch under the bonnet so your no tempted to switch it while your engine is running. Simple as ABC

Hasn’t affected the computer in any way shape or form and cost less the $50 to do.

Use a good size cable. Over do it even ! That way you’ll eliminate to a large degree any difference in charging rates between the different batteries. Engineers, auto electrician alike recommended to keep it simple. Less bits , less problems.

If you like a pic or two of it.. let me know your email addy and ill send you some
Hope this helps


AnswerID: 38838

Follow Up By: Andrew (Qld) - Saturday, Nov 29, 2003 at 08:36

Saturday, Nov 29, 2003 at 08:36
Thanks Bill
It seems to be the simplest method. I geuss the only down side is that you need to lift the bonnet to change the setting. It also acts as a bit of an anti theft device if you turn it off. Did you switch the neg. side. I was advised to do this. Would like to see the pic and diagram if you have them. (vastonline@bigpond.com)
Thanks once again
PS How have you found the V8??
FollowupID: 82709

Follow Up By: koh - Saturday, Nov 29, 2003 at 15:33

Saturday, Nov 29, 2003 at 15:33
Andrew no problem with the pics etc... Ill have to do them for you on Monday as I usually read this forum from my work.
I have a switch on the positive. I would have put it on the negative if I had traveled the cables a longer distance, reducing the risk of the cable rubbing through on something and sparking but I have just run it through some of that cable tube stuff what ever its called that’s concertina style and over the radiator. There’s a grove there that it fits in nicely, not too much heat where it lies. It’s not much over a meter in length.
The V8. Best LC I have had. be interested to compare fuel consumption with you some time. I'm pretty happy with it though.
couple of little things I have found. loose bolts on the underbody protection plates, and a couple of loose bolts under bonnet... plastic cover over the motor needs a washer on one of the bolts, passenger side I think... you’ll get a vibration noise come in some time that will give you the craps, MAKE SURE you put a clamp or zip tie on the transmission hose going to the oil cooler.. its right next to the fan and if it hops out of the clip... the hose will hit the fan and in no time your trans is history, The was a post on here about in a little while ago.I mentioned it to our local Toyota blokes and now its part of their PD. take the belly cover off underneith... you’ll see it...if you want radios put in the “dash pod” is a nice way to go,, I can take some pics too if you like.
watch the material on the back of the passenger seats... its like tissue paper and looks like crap if you damage it. get GOOD floor mats the carpets could be a tougher grade but that’s a minor issue.
one of the little knobs on the air vent near the air-con came loose and fell in half... that was interesting and finicky putting that back in place.
but I have loved every minute driving it. i'm sure you will too.

talk again

FollowupID: 82725

Reply By: Member - DOZER- Saturday, Nov 29, 2003 at 10:53

Saturday, Nov 29, 2003 at 10:53
Gday Andrew
You need to ask yourself what you want out of the dual battery setup. If you are setting it up for winching, that will be a different circuit to having a deep cycle camping setup. If you want it all automatic, there are a few isolators on ebay at the moment. Somewhere in between is a simple solenoid rated at 100A at least, that gets its signal from the charge fuse. This is automatic, but you need to be aware of 1 scenario that might damage the computer... if the mainbattery is almost flat, and she starts, the spike will upset things a little (or alot).
There is a proceedure on www.lcool.org (in the tech pages) that shows this last setup.
Rototronics make the best auto isolator for your batteries IMHO. It works differently, By charges each battery independantly. The other autos simply gang up batteries or join them together whilst alt is charging.
If you dont mind it being manual, the marine switch is a good idea. You can swap batteries every fuel up when you check the oil.....
Andrewwheredayathinkwer mike?
AnswerID: 38872

Reply By: Andrew (Qld) - Saturday, Nov 29, 2003 at 14:32

Saturday, Nov 29, 2003 at 14:32
Thanks for the info. At this stage the unit will be used for lighting and a fridge. No winch. The local Auto Elec suggested the marine switch as you can test the staus of each battery. Also, the new 100's are running a temp regulated alternator. Once engine temps are reached the alternator cuts back the charging rate. This has something to do with the new emission controls being bought in the next few years. So the solenoid and the cheap controlers will take a long time to charge. The wiz bang Rotronics as you mentioned will do the job , but at a price. At this stage I am looking at the marine switch.
AnswerID: 38878

Reply By: Member - Eric- Sunday, Nov 30, 2003 at 08:47

Sunday, Nov 30, 2003 at 08:47
My set up

180 amp relay conecting both batteries through a ACC trigger , this means you can isolate a battery when ignition is off , and there is no power to relay under chranking , but both batteries charge when running , I also have a key type bipass swith to connect both batteries if one goes flat or winching is requiered Venus Bay
AnswerID: 38936

Reply By: ThePublican - Sunday, Nov 30, 2003 at 12:42

Sunday, Nov 30, 2003 at 12:42
70 thousand $ vehicle and your worried about the cost of a rotronics system ?? false economy !!
AnswerID: 38954

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