Finished up a slightly different take on a dual battery setup - now to see how the two batteries behave with each other.
Took out an 8(!) year old AGM battery that was starting to go - not nearly as much oomph as it used to have. Still, 8 years if a good run for a battery. I've added a bunch of stuff to the car over that time frame, though. On board air (dual Arb tucked in the rear cargo cubbyhole), a winch, lights front and rear. Wanted to get a deeper cycling style of battery, as well as a dual battery setup in case something happens and one goes dead out in the middle of nowhere.
But I also didn't want to reorganize the engine bay too much. So I thought about a 'tiny' battery. I've been using them for years on a couple of my other cars (turbo LS swapped Volvo 240 wagon, and my little rat rod Volvo 544) as a replacement for the full sized battery. And I've had no issues with them at all. They crank normally, in regular use they seem 100% adequate. If I had a car with a starting issue, or weak cranking in general, or something like that, obviously, the tiny battery has less Amp-Hours - so less spare capacity to play with.
So I used a Braille 14115 battery as the start/car battery. It's really small. The Odyssey PC680 is similar and usually a lot cheaper, but it's a little bigger. And an Optima yellow-top for the house/winch battery. I got a new holder for the Optima that reaches around the ends of the battery - and installed that in the normal spot in the 4Runner. Then welded on a bit of bracketry on the engine end of it to hang the Braille mount on.
Then I mounted a Blue Sea ACR switch on top, after pondering various other locations. There's not a lot of spare room in an 4Runner engine bay! Hanging it on top of the Optima makes removing and replacing the battery a bit more complex - but not by much.
Hooked the 'start' wires (heavy wire to the starter, slightly smaller one to the fuse box), as well as the engine block ground wire both to the Braille. Hooked the winch/house wiring to the Optima. I originally wired my winch wiring up to use a receiver cradle mounted winch, with Anderson connectors front and rear, since then I've instead permanently installed the winch in the front bumper instead, but left the rear wiring in place, with a solenoid to turn it off and on. And I've just been using that as a main 'house' bus - the OBA and lights are connected to it. Then a couple of short positive connector wires to connect the two batteries to the Blue Sea switch.
A couple of pics - it was sprinkling off and on while I finished it up.
The Braille, Optima, and Blue Sea ACR under the hood:
The Blue Sea remote switch in the dash:
I had an old, somewhat fried Braille I'd swapped out of my wagon which I initially tried to use. It cranked slowly, wouldn't start, but bridge the house battery in and it would crank like normal. Good test of the 'dead start battery' scenario. So I took the good Braille out of the wagon and put it in the 4Runner - with the two separated and it running completely off the Braille - starts and acts entirely normal.
