How do you replace the 12v battery?

Here is a good video that should help.

 

Besides the official Toyota battery, these two batteries are available in the US and safe.
Optima DS46B24R Optima battery direct fit replacement for Prius 2004 + & Plug-in Prius with Instructions
Toyota Prius Starting Battery - Exide Edge 51JIS Flat Plate AGM

 

I use the Optima Yellow Top. DIY two years ago. Working good. My 2005 have no issue ever since I owned it preowned at 2008. Only responded to the recalls.

 

The Optima Dealer sends instructions, both batterys are fine.

 

If you are slightly mechanically inclined, it should be no problem. The hardest thing is the top screw for the duct on the traction battery. When I did the job, I put some grease on the screw head that kept the screw in the socket and then was able to start it in that way. The screw is hard to see and difficult to get your hands in there while holding the duct in place.

Like you said earlier, unhook the negative first and connect it last. When I changed ours, it took me about an hour. I am disabled, and was able to do it with little trouble.

Tools used:

10 and 12 MM socket, ratchet for sockets, a couple of extensions, 10 and 12 MM wrenches, a flat blade screwdriver and a small hammer. Oh yeah, a little grease. Tape works Ok too from what I have read. Anything to keep the screw in the socket when you stab it back in the hole on the duct. If it falls, you have to fish it out with a magnetic pickup.

The battery is under the rear hatch on the passenger side. Take the black box out to expose the spare tire. Then remove the little cover on the right rear floor. You will then be able to see the battery. It makes the job easy if you will move the brake power back up (black box next to battery) out of the way by removing three bolts. You can also unplug the box if you want to, just make sure you plug it back in before you start the Prius or you will get a light on the dash and DTC code. Then unhook the negative, (take the bolt out where the cable hooks to the car body). Then remove the screw and bolt holding the vent duct for the traction battery and move it out of the way. Pop the red cover off of the positive end (screw driver helps). Remove the bolt and nut that is holding down the strap clamp on top of the battery. Loosen the positive terminal nut and wiggle the terminal while pulling up. It also helps to spread the terminal a little bit after you have loosened the nut with the screw driver. There is also a little screw like clip on the positive terminal that attaches to the battery strap clamp. You can remove that clip thing and pull the strap separately or remove the strap and positive terminal together. It is easier if you pull the strap clamp first. There is a little vent tube that goes in the side of the battery. Pull it straight out. (It snaps in place). Once you have everything done as I described, you should be able to pull the battery straight up and out. After that, simply take the negative cable off of the battery, transfer it to the new battery, and then reverse the process.

It sounds like a lot of work, but it is not that bad. Like I said, the hardest thing is the top screw for the plastic duct. It is hidden on the side of the car behind the carpet. Look for it, you will see a notch in the carpet on the side. The screw is visible with a flash light if you get your head down there.

Just be patient, and before you do anything either make a sketch of what you see or take a couple of photo's. Also, if you have any doubt, keep all of the fasteners sorted so you know where they go when it is time to put it back together.

It is also a good idea to make sure the new battery is fully charged before you install it. A new AGM type battery should measure at least 13.0 volts when it is fully charged with a digital volt meter.

 

No biggie, just a lot of keyboard use. You may find you have to remove the positive terminal before you remove the duct from the traction battery. I wrote that from memory of the job back in January, but reviewed a pic of the installed battery and realized the order was not entirely correct. It is a relatively simple job IF you are mechanically inclined. Heck, Julia 2001 did one last year, even though she did not like the end result with the "Yellow Top" she bought. But that's another story. Good luck to you.

 

I suspect you did not buy a DS46B24R, the model for the Prius. It uses the existing tube.

 

Take it back.

 

Yes


Dry it out and try to locate where the water is coming in. Seal the leak.

 

It looks like you found this link here.

12 volt battery change and alot of water under it | PriusChat

The only real way to find the leak is through trial and error. Leaks can be found in more than one place. Some find the hatch seal is leaking, others find the seams in the body are leaking.

If you find a bad seam, use the stuff that edthefox5 ( Auto Body Shop Paint Supplies 3M 08656 Brushable Seam Sealer for Joined Seams | eBay) mentioned in post #10 of the link above. If it is a hatch seal or something similar, you will need to repair or replace said seal.

A water hose and a lot of patience will help you find the leak. It will be cheaper if you DIY rather than paying the dealer to fix it for you. FWIW, you are not the first person to find water under your battery in the Prius.

Unless you over tightened the top screw it should snug up. It is a self tapping screw that screws into a piece of plastic in the side of the body.

 

GasSippr, if you have a digital voltage meter, can you post the measurement that was on that new yellow top when you got it out of the box? What was the final cost of that yellow top?