I am thinking of getting a power inverter and some extra goodies on my truck. I plan on first upgrading the stator on my alternator to a 90 amp one then possibly doing dual batteries. The only issue is where the hell to mount it? I am thinking behind the rear seat inside a plastic box. I probably will run a optima battery so no problems of venting and corrosion. It got me thinking which is a bad thing sometimes then things tend to get expensive. Why not run dual optimas in battery boxes in the back? Is getting a battery switching unit really necessary? What are the cons for doing this? Also should I just run one in the back and one in the front and adhere to the K.I.S.S principle?

93 Toyota SR5 5 Speed V6 4 Runner 33x12.5 MT's, FJ80 coils, Low pro bump stops http://www.cardomain.com/id/934rnr

I don't know why I missed this post. But I just now saw it, sorry SHAD. I don't know about your 4runner, but in my Pathfinder, I'm stick two Optima's side by side in the stock battery location. I just had to relocate the radiator overflow bottle and 'square' off the corner support. I have pics, but need to get off my duff and send picturetrail their money. I've gotten tired of doing the free thing every month. I can email you some pics if your interested, but again this is for a '94 Pathfinder, not a 4runner.

If you can't fit the battery in the engine bay, you'll have to stick it in the rear or fab a mount for under the truck. You can put them both in the rear if you like (its really not anymore difficult then putting just one back there), this makes room in the front for an air compressor or something.

I'd get a battery isolator/combiner. You'll love it the first time you have to switch over because you ran your main battery down.
HellRoaring Technologies makes a great solid state one.

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'98 FAD FrontyKC
152,000 miles
Packin ARB'd 9"(5.00)& Tornado w/ Dual Remotes;-)

If you dont use an isolator, you at least MUST use a fuse or fusible link between the batteries. I'd recommend a 60A fuse between the positive terminals if you are running them in parallel. If one battery develops an internal short (and thus a voltage difference between the two batteries), you could have a big problem on your hands when it gets hot and catches fire.

I just put in an Optima yellow top.. and am going to pick up a red top next month just for starting the truck. I'll be putting in a ~60A isolator and a big fuse just to be safe.

All the accessories (including all my lights) will be run off the deep cycle, along with the winch and my stereo amps. The red top starting battery will be wired to power the starter, EFI, and other components required to make the engine run.

This way, I could leave my lights, stereo, etc on.. or run the winch until the deep cycle is dead.. and then be able restart the truck and recharge the yellow top in less than an hour while running. Might need a Quest alternator to handle the load though. The yellow tops will recharge from dead to 100% charge in 1 hour.

That's the same setup I'm looking into... Yellow top for the goodies, red top for starting.


Heavily Modified 2001 SE 6cyl 5spd 4x4 Solar Yellow

That is what I also plan, but I have two red tops already, when one finally needs replacing, I'll get a yellow...or maybe stick one red top in the wifes car and go buy a yellow. It all depends on money, money and more money. But I want to get this electrical done soon, I'd like to get it done BEFORE I put all the goodies on, not after.