So I decided I needed Dual Batteries. Going into this I knew next to nothing about electricity. 50% of the time I put the AAs in the TV remote upside down. Friend of mine had them put into his TACO by a local 4X4 shop and it is a very nice setup. However it cost him about 1/3 the blue book value of my 4Runner. There had to be a better way. So I decided to educate myself and after hours and hours of internet searches and reading I felt pretty confident I could set this up myself.
I decided to go with a solenoid style isolator that was wired to close when the ignition was on. The idea being that both batteries charge when the rig is running and when its not running the aux battery is isolated. Then I'll run all my accessories off of the primary battery, saving the aux for emergency starting only. In theory if I run my battery down too far to start the rig, as long as there is enough juice left to engage the solenoid, the 4Runner will draw from the aux battery to start and bing bang boom... I'm not stranded.
What I used was a 200amp Solenoid, 0/2 Wire, and 2 200amp fuses. I just used plain old car batteries, nothing fancy. I know there are much better Deep cell batteries but remember I'm on a budget.
The biggest struggle was finding a spot for the extra battery. There isn't much room under the hood but I really didn't want to sacrifice cargo room in the back or deal with running heavy gauge wire all over the place.
Figured I could relocate the windshield washer reservoir and put them right there side by side. That was horse scat.
What I really wanted to do was but the Aux batt where the factory air box was... but the factory air box was there... so I came up with a pretty simple plan. Auto zone hoses and the smallest cone filter I could find.
After some cussing and banged knuckles I finally got the thing in there. Notice my supper fancy strapping to hold it in place.
Second strap holding it in place
overview of under the hood before wiring in he solenoid and fuses.
Finally all the fuses and the solenoid wired in and working like a champ.
Not necessarily professional but then again i'm not too ashamed to open my hood. Total cost was around $250 including a $100 battery and some various wire crimps and other tools i needed. I haven't run my battery dead yet so i can't say that it will work as planned. But I can tell you via voltage meter that both batteries are charging... so there is that.
