2006 Prius - when will the car battery quit ??

Hey Bill- I have a 2006 with 40 thousand miles as well and it is still on the original 12V. Must have been a good batch that year. I check the voltage on a regular interval however. It is still reading 12.5+ after sitting over night. H

 

A digital volt meter will do, positive lead to the jumpstart terminal in engine compartiment, negative lead to ground (bolt or other bare metal on engine or body).

My 2 cents: I'd just replace it, regardless of results, it's had a good run. I look on batteries as expendables, something you replace periodically, hopefully before they start acting up.

 

My advice would be to suspect and change out your 12 volt battery at the first sign of odd behavior, the computers can glitch with too little power. The life of any 12 volt car battery depends on the heat of summers and the cold of winters, in a mild climate it will last longer than in severe weather.

Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

In the US, I know of three 'safe' choices, the battery your Toyota dealer sells, an Optima Yellowtop and an Exide Edge, both designed just for the Prius. (AGM chemistry with externally vented cells, using reverse polarity JIS Posts)

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

 

Alternatives also include information in this thread.
Fitting mobility 12volt AGM battery. | PriusChat

 

I just replaced the 12v battery on my 2008 with 44,000 miles. Bought the Optima Yellow-Top two weeks before the car failed to start after the wife made a short trip. I used the new battery to jump start the car.

I also suggest you get a new battery. Just to be safe.

 

I changed ours in the 09 Prius that we have. I went with the battery that Toyota offers. The one I replaced was getting weak. Low voltages according to the test that is documented here on PC. I also noted one time I saw the red triangle for a couple of seconds when entering "Ready Mode".

I too recommend you change your battery BEFORE it fails. Batteries seem to fail at the worst time. With the Prius, there really is no particular thing to watch out for other than voltage drops. Yes, the computers will do strange things when the voltage is low. That includes readouts on the dash. One time I noticed the gas gage was fluctuating when ever the ICE would light to charge the traction battery when I was parked using the A/C. Other oddities included error codes on the MFD in the LAN section. Since the battery has been replaced I have noted no oddities at all.

FWIW, if you are mechanically inclined you can change the battery yourself. I mention this due to the fact that Toyota charges a rather high fee for the service. When I changed ours, I got quotes from three different dealers. The cheapest was $50.00 plus the battery. The most expensive was $125.00 plus the battery. You can expect to pay between $150 to $200 for a good battery for the Prius.

FYI, a new fully charged AGM type battery will measure 12.9 volts or higher with no load at the posts with a digital volt meter. The Prius requires a vented AGM type battery that has reverse polarity on the posts. The posts are also smaller than normal batteries. The posts are classified as "JAS" type posts.

As mentioned, there are limited sources for the battery.

Good luck to you.

 

Living in the same climate, the 2001 Prius just had the second replacement, so that is working out to about 6 years per battery.

(Implied, buy not explicitly stated-- this is the 12V battery.)