How to change auxillary battery

Ernie: Which battery are you going to use for the replacement battery? If you get the Optima Yellowtop with the small posts - I can pm you detailed instructions. Tom V.

 

It's not too big a deal--you just have to get a few things out of the way.

Remove the trunk carpet mat, floor section, under-floor storage tray and the covers over the left and right portions of the trunk (you may be able to leave the left one in but I got it out of the way).

I like to unhook the negative battery terminal from the 12v battery first so I don't have to worry about grounding anything out with a wrench. If you don't want to lose the memory settings, you can attach a 12v power supply or battery to the jump-start terminal inside the fuse box under the hood to maintain power to the memory. Otherwise, a few things need to be reprogrammed later such as the radio presets, power window auto-up, and reverse/seat-belt beeper disables. It'll also lose the MPG average on the display.

The battery's in the rear, passenger-side corner of the trunk. The black box mounted just inside of it is the capacitor pack for emergency braking power in the event of an electrical failure. Move the capacitor pack out of the way by undoing the bolt on it's floor bracket and the small bolt on the top of the black box attached to the rear wall bracket. On that same wall bracket, there's a 12mm bolt just under the cargo anchor that you may have to loosen to get the capacitor pack out from under that wall bracket. I left the capacitor pack plugged in but just moved it aside.

Then just remove the section of ventilation ducting that's just forward of the 12v battery by removing the bolt holding it to the floor and the bolt holding it to the passenger-side wall (you may need to lift the interior paneling out of the way just a little to access the side wall bolt--be careful not to lose the bolt.

The red, plastic + terminal cover has three clips holding it to the black plastic connector assembly that can be carefully pried open with a flat-bladed screw driver. With the red cover removed, then you can remove the + battery terminal.

Then remove the battery hold down by removing the bolt attaching it to the floor and the nut on the threaded rod near the side wall (be careful not to lose the nut). I left the wiring harnesses connected and just moved the whole assembly aside.

Then pull off the small black vent tube fitting on the front side of the battery and you're good to go!

I'm on the original battery on the '07 but I took it out and added distilled water to all the cells. Every cell was low on water. I'm hoping to continue to use the original a while longer.

Eric

 

I found this on youtube. Its a bit lengthy and the 1st 5 minutes are boring, but it is aimed at a novice. The last 4-5 minutes are good, but don't show the option to keep it powered up, or how to reset.

Hope it helps

 

To avoid losing all your presets, things like radio settings, and possibly auto-up on the door windows, it's good to supply low amperage voltage to the car while replacing the battery.

I had a 0.5 amp motorcycle battery trickle charger, have used it on previous, non-Toyota vehicles, with no ill effects.

Basically, at the outset: hook the charger up to the jumpstart terminal in the underhood fuse box (positive to the terminal, then negative to a metal grounded point, on engine or frame). Then plug the charger into 110 volt AC. Then replace the 12 vot battery. Then disconnect the charger in reverse order. Your settings should be retained.

 

When you do this, how do you keep the aux battery's positive lead from contacting body metal? Wrap it in cardboard, cloth, rubber?

 

i have an 08, but hope to get many more years out of the battery, but i only have 30,000 miles.

 

Yes wrap the Positive cable good.

 

I put it inside two plastic sandwich bags. Worked fine.