100 Series Turbo Diesel L/C

Submitted: Wednesday, Mar 29, 2006 at 21:17
ThreadID: 32329 Views:9415 Replies:14 FollowUps:3
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My Turbo Diesel Landcruiser Sahara has 2 factory fitted batteries (standard on this model)
I want to isolate one of them and use it as a auxilary battery by installing a battery isolator. However I can't decide which battery to isolate as both seem to have electrical components coming from them.

If anyone is familiar with this particular model (2006) I would appreciate some advise if it is possible/allowed to isolate one of the batteries and which one

Also I am not sure why/what reason this model comes with 2 batteries

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Reply By: Bilbo - Wednesday, Mar 29, 2006 at 22:10

Wednesday, Mar 29, 2006 at 22:10

From what I can gather (before mine got stolen!!), the 1HDT-FE Turbo Diesel Landcruiser needs both 12 volt batteries for cranking that big donk. It's either fit 2 batteries in parallel to get 12 volts with large ampage or fit one monster size 12 volt battery. A battery with that sort of capacity would prolly have to be specially made just for Toyota and their Landcruisers.

Vehicles are often advertised as having a "dual battery" system, when in fact that's not really the case as both batteries are required for primary usage.

Putting an isolator, such as a Redarc, between the batteries would leave you with only one battery for cranking unless you kept enaging the emergency override on the Redarc.

I think it may be best if you fit a third battery in the back of the truck, seperated from the those 2 primary cranking batteries by an isolator such as a Redarc or Rotronics.

I had a Redarc in my 'Cruiser and was well pleased with it's operation.

Good luck,


AnswerID: 163753

Reply By: Member - Davoe (Widgiemooltha) - Wednesday, Mar 29, 2006 at 23:01

Wednesday, Mar 29, 2006 at 23:01
I could be wrong But I thought the vehicles and there are a few i think Jacks were another as well as toyota Surfs. Had the duel batterys as a European spec thing for those -20 deg mornings. Definitly dont take my word but i think you can chuck a decent 700cca starter in and isolate the other battery as our Mild weather is far less taxing on batterys
AnswerID: 163767

Follow Up By: Member - George (WA) - Thursday, Mar 30, 2006 at 11:46

Thursday, Mar 30, 2006 at 11:46
Thanks Davoe, I will certainly look at a larger capacity battery when they are due for replacement

FollowupID: 418637

Reply By: Trekkie (Member - WA) - Wednesday, Mar 29, 2006 at 23:42

Wednesday, Mar 29, 2006 at 23:42
George - I am sure Davoe is right, the standard set up is for European conditions. I have had Rotronics isolator since shortly after purchase of the vehicle. Without going outside and looking, I think the RH battery is now my auxillary and the LH is the cranking. I have replaced both since new with the auxillary to suit winch etc. I would need to check Rotronics specs to see if it uses both batteries for cranking.
AnswerID: 163773

Follow Up By: Member - George (WA) - Thursday, Mar 30, 2006 at 11:48

Thursday, Mar 30, 2006 at 11:48
Hi Trekkie, RHS Drivers side, LHS Passenger side ??

FollowupID: 418638

Follow Up By: Trekkie (Member - WA) - Friday, Mar 31, 2006 at 01:23

Friday, Mar 31, 2006 at 01:23
RHS Drivers side = Auxilliary
LHS Passenger = Cranking
FollowupID: 418818

Reply By: Muzzgit (WA) - Thursday, Mar 30, 2006 at 00:09

Thursday, Mar 30, 2006 at 00:09
Left side is cranking.

There is room in there for another battery if the fuel filter and a couple of other bits are moved. ARB will know what's needed.
AnswerID: 163777

Reply By: Richard - Thursday, Mar 30, 2006 at 04:31

Thursday, Mar 30, 2006 at 04:31
Also have a 2005 TD100 and wondered why the 2nd starter battery but assumed it was needed to crank the big engine. I put another sealed battery in the rear running through a Pirahna isolator which I transplanted from the previous vehicle.
AnswerID: 163788

Reply By: Member - Matt L (NSW) - Thursday, Mar 30, 2006 at 06:30

Thursday, Mar 30, 2006 at 06:30
HI George,

Leave the two batteries that are there for starting, you can never have too much battery power. There is room for a third battery to run all you axillary equipment and if you ever get careless and flatten it you will still be able to start your car in the morning.


AnswerID: 163790

Reply By: wheeler - Thursday, Mar 30, 2006 at 07:35

Thursday, Mar 30, 2006 at 07:35
I have a 2005 100 TD . I have split the 2 oe batteries and also fitted a 3rd battery. The 2nd & 3rd battery are now wired in parrallel and isolated from the main battery via a battery seperator. I have also fitted a link switch on the dash which joins all 3rd batteries, should there ever be a problem with the main battery. The 2nd oe battery is fitted for cold weather starts in the nth hemisphere and is not required here. Any ARB store can do the above fitment for you.
AnswerID: 163799

Reply By: Member - George (WA) - Thursday, Mar 30, 2006 at 11:45

Thursday, Mar 30, 2006 at 11:45
Thanks to everyone for your input. I was also inclined to think that the two battery set up is mainly for the cold winter locations. Some suggested that LHS is auxilary and RHS is for cranking. Can that be clarified by Passenger or driver side please.

Also what is currently running from the "Auxilary" battery ??
AnswerID: 163856

Reply By: Geoff M (Newcastle, NSW) - Thursday, Mar 30, 2006 at 12:34

Thursday, Mar 30, 2006 at 12:34
I’ve just been chatting to my mate who owns one of these in a GXL variant. He says the batteries are paralleled by a cable. This makes them behave as a single large battery.
He's separated his and installed a charge isolator between them but he wasn't clear on what you've got to swing from the one that becomes the auxiliary battery to the one that becomes the starting battery. (He didn't physically perform the changeover)
For what it's worth the Table Top’s and Troopy with the turbo diesel both have a single battery of 90Ahr capacity and 650CCA (According to the battery manufacturer’s specifications) for starting so it would appear in some installations Toyota believe one battery is sufficient.

Hope this helps,

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AnswerID: 163866

Reply By: Member - Prickle (SA) - Thursday, Mar 30, 2006 at 14:23

Thursday, Mar 30, 2006 at 14:23

I have a 2004 TD 100 S, 1HD FTE motor. Bilbo is correct, the 2nd is due to the motor size and the need for extra cranking power in cold weather.

Toyota advised me that I would be risking my warranty if I isolated one of them.

I have a Blue Apple Thumper in the back with redarc charging system and love it.

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AnswerID: 163885

Reply By: wheeler - Thursday, Mar 30, 2006 at 15:15

Thursday, Mar 30, 2006 at 15:15
Toyota will try and void your warranty if you sneeze in the car.
As posted above if the 2nd battery is needed because of the motor size why do the 78/79 series which have the same motor not run parrallell batteries. I have run the split batteries with the 3 rd aux for over 100000klms with no problem. I use it for my fridge which is permantaly on and for camping lights etc and never had a prob. I know that ARB also do this system for the police.
AnswerID: 163890

Reply By: Member -Dodger - Thursday, Mar 30, 2006 at 15:39

Thursday, Mar 30, 2006 at 15:39
When you work out which one you want as an aux battery or which one shoul be the aux battery just fit a simple soloniod syatem in so that when starting the vehicle IE ign on both batterys will be connected.

Just a thought.

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Cheers Dodg.

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AnswerID: 163893

Reply By: 100TD - Thursday, Mar 30, 2006 at 16:34

Thursday, Mar 30, 2006 at 16:34
Im surprised only 2 people mentioned VOID WARRANTY when these 2 batteries are split.Toyota told me straight out that my warranty will be void if i split via redarc/pirahna etc on any electrical problem that the car may have possibly had.Leave the 2 factory batteries in parralel and add a 3rd to L/H rear cnr of engine bay via isolator of some description(i have used a pirahna and it works a treat!)I replaced both main batteries with yellow top optimas and a 100aH remco gel cell for an auxillary(you can leave your oe main batts just add a good 3rd as aux)I have a 2003 100TD auto with winch/many driving lights and lots of other electrical accessories and never had issues of any sort in 3years with fridge running for 3 days without running car also running lights etc from same aux battery before it shuts down at 11 odd volts.Hope this helps.Paul
AnswerID: 163901

Reply By: Sam from Weipa Auto Electrics - Friday, Mar 31, 2006 at 07:46

Friday, Mar 31, 2006 at 07:46
Thats all a load of rubbish I have split battery setups in a 100 series 5-10 times so far as long as you run something like a n70zz or mf95d31r supercharge gold series (760cca) as you're starting battery toyota can not void you're warranty I have a 79 series ute and it only has one battery for starting and its the same motor and dont have a drama. as long as you do the instalation properly it should fine dont use the standard toyota batteries as they are to small for the job. use a nice trojan deep cycle or agm battery as the second battery.

cheers sam
AnswerID: 164029

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