About $138 for the solenoid at Wrangler. Add a switch and a few wires and you have the Painless kit. If you go the solenoid route, be sure to get one rated for continuous duty. You can find starter solenoids for domestic vehicles, but they are usually not designed to be on for hours at a time. You can run a winch off the main (and only) battery just fine. I did that with a single Optima red top and the stock alternator for several years, no problems at all.

 

where is this Wrangler?...im always up for cheaper.

 

Link to Wrangler Power NW is on my page, which was posted earlier. Has parts lists, wiring diagrams, etc.

 

I'm updating my system to incorporate a marine type battery switch to select which of the dual rear batteries gets charged and also to separate them...not working like I want it the way I got it...I'll post up when I get it handled.

 

northfacer581's thread inspired me to look at the possibilites for dual batteries in a 3rd gen. upon reading his thread, i was almost positive i had seen someone mount 2 optimas side by side in the stock battery location. well i searched around and finally found a short statement on ttora which triggered my memory. it was on the project truck Mayan Hunter, a 2005 tacoma in which they did this.

---->

does anyone know if there is room to do this in a 3rd gen 4runner? i dont even have 1 optima so i cant check. possible? good idea/waste of time?

 

I believe they had to do a lot of relocation. Im sure anyone can do it, its just whether or not you want to put the time and effort into it.

 

i had a red top optima in the stock battery location. there really was not that much room to where it would be simple to do. i believe it really would require some moving around. ill snap a picture tommorow of the red top i have laying around placed beside the battery thats in there now. not too much space.

 

Everything is possible, just not probable w/o you doing some custom fab work as I don't think there is a "kit" just floating around to put (2) batts up front on a 3rd gen. I remember that write-up as well and even still have the magazine, but they never explain enough of anything. You don't want (2) batteries up front that aren't securely mounted.

It could be done, you'll just have to figure out if you got room, as I think they had to move some stuff slightsly IIRC.

 

I determied that I could stuff 2 Optimas into my 1st gen, stock battery location. Would require moving some things and would leave the battery close to the engine. But I opted for two smaller form-factor batteries. You would easily place two of the Odyssey-type batteries in the stock location, or I shoved mine under the truck where they have lived for over 7 years now:

 

Hey man, I have two optimas in my garage. Come over and see for yourself.

 

Well I've told of how I did it many times, but maybe I can do it one more and be done with it! I have a Yellow top in the factory location, and a Red top on the other side. I had to use a different intake to do it. With a bit of mild fabrication there is definitely room on the passenger fenderwell if you move the cruise control and a few other goodies around. See Bajataco's setup for that route...

Engine Overview

Second battery

Isolator

As far as hooking 2 batteries together without any isolation device as it was said above, bad idea. I got 2 brand new batteries from the same shipment the same day same same same. Hooked them together, and it took me a few weeks and a talk with a pro as to why I always had dead batteries...

I'm not an EE, but I think I can explain it easily enough. Electricity flows from greater concentration to lesser concentration, we can agree on that. Well, let's say I've got battery A at 13.8 volts and battery B at 13.5 volts. I hook them up. Immediately battery A's extra voltage flies to battery B... but then battery B has more, so it shuffles voltage back... Now this is a very small voltage, it really is. But this cycle goes on indefinitely, and there is a small loss every time it happens. You come out a day later, it's probably okay. But maybe 3 days later? They're both dead, and VERY discharged. Basically you don't want those 2 batteries to "talk" to each other. They are like great coworkers who work horribly together.... as long as they get paid (charged) and don't have to work with the other, they'll do just fine. Put them together you've got a scuffle and both go down the crapper...

Okay that was a weak analogy... but don't listen to me, there's plenty of info out there on this.

 

98LTD...someone made a boo-boo with those image links.

 

Should work now... having one of those days where I really regret even waking up!

 

I've measured around my Optima and there's no way a 2nd batt is gonna fit. The Maya Hunter install is super clean but I think the only way to make it work is to use '98LTD's setup. I've looked under the truck and haven't found anything suitable. I have the dual battery isolator from Painless Wiring (Summit Racing-$100.00 free shipping) now I just need to make it work. I'd love to see additional setups...what about routing wires to the cargo area and only packing the Battery around when you know you'll need it--wheeling, winching, etc??

 

You can find those at Wrangler Power NW, link to their page on my dual battery page, posted earlier.

 

I've had two Optimas in my stock battery location on my '04 Taco. The inboard Optima rubs the radiator mount and it is extremely tight but you might be able to make that work.

Another way may be to use two Odyssey batteries in place of the Optimas since they are .25" less wide, for an overall savings of half an inch in width.

 

I am a little new to all this, but my question is, we had a diesel truck that had duel batteries stock. How does this work? Does starter use both batteries during start? And how does it charge both batteries? Mostly I want to know if I were to go to a junk yard and find a large diesel truck could I pull an isolator or solenoid? What makes these things work? Because if I could use an old one from the junk yard than I am all over this.

 

It works however you set it up. Mine uses 2 batteries tied together with a solenoid (i.e. big honking relay). If the relay is on, both batteries in parallel to start, winch or get charged by the alternator. Solenoid off, two separate batteries, one hooked to the engine/alternator and one floating for accessories.

 

I think this is bad advice. You had something else going on in your vehicle beyond "dueling batteries. Every boat I've owned, and every one I've done battery installations into, has had multiple batteries in one bank that were not isolated. My current boat has 2 big 8D sized AGM batteries that have been hooked together continuously for 4 years now with no issues. Match the size, type, and age of the multiple batteries and you should have no problems.

 

Brian,
I appreciate overkill in just about any situation, but why 3 batteries? I had three on my previous pickup and ended up taking one out because I never needed that much capacity, and it took a long time for the stock alternator to charge them. Just curious.