Prius battery failures

After a routine maintenance, the small battery failed in my low mileage 2005 Prius and then two months later the large battery failed. Coincidence or something wrong in the electrical system?

Hard to tell. You might try asking over at

As far as I know, you’re the first person to report a large battery failure on a Prius. Please give us as much detail as you can.

We need to know the mileage of your “low mileage” 2005 Prius, and if you could provide its maintenance history it would be greatly appreciated.

Failure of the large battery is very unusual. Isn’t it covered by the vehicle’s warranty?

We need more information.

FOR THOSE WHO WANT THE WIRING DIAGRAMS FOR THE 2005 TOYOTA PRIUS HYBRID: Use your library Web site, go to ARRC (Auto Repair Research Center), put in your library card number, and enter the site. The wiring diagrams are seven pages long. Print’em and read!

The warranty period is 7 years, 11 months /96000 miles. KBezold, your mileage?

The mileage is at 34,000. I’ve kept up with all recommended maintenance and had no problems at all with the car until the battery failures.

In the past week, when I would start the car in the AM, the battery indicator would go down to just one bar. After driving it would recharge and be OK all day but repeat the cycle the next AM.

1 bar is 40% state of charge. The cars computer’s keep the charge between 40 to 80%. Go to that link that texases gave to find out more.

My 2005 failed at 123,000 miles. When did your’s fail? I would say something is wrong with the electrical system. Did Toyota pay for it?

I have a 2009 Prius with 3500 miles that would not start a few days ago. I did not drive it for a week and it appears the smart system drained the battery. This dot seem reasonable.

With all the electronics that modern cars have, a week or two downtime isn’t unheard of for a (normal)battery to drain

My 2005 Prius (35,000 mi.) did that too. I pushed the button in to isolate the electronics (they said this) and it lasted longer but did drain down.


Thousands of Prius owners have suffered main battery failure. So many that the dealerships have been instructed and trained to isolate the defective cells and replace them instead of replacing the entire battery… There is no free lunch with electric cars…GM learned that lesson with the EV-1 and will delay the VOLT until they are sure they can absorb the inevitable battery failures…

We had that Prius post about a month ago from the woman that paid $2300.00 for a main battery,what did yours cost? (I remember her’s was a 2001)

I get this feeling from the posts from Prius owners that they feel they should be better protected from a major automotive repair than the owner of a “normal” car is, something like payback for being “greener”.

Thousands of Prius owners have suffered main battery failure.

Where are you getting data from?? According the the following web-sites…the failure rate on Prius and other Hybrid batteries…is no where near that. According the what I’ve been able to find on the net…the failure rate is around .003%…that’s EXTREMELY low…and will account for only a few HUNDRED batteries.

If the OP was the original owner…then the cost is $0…The battery is still under warranty.

Read the URL’s about Hybrid batteries I posted above.

Hey Mike thats what the woman posted,she claimed it cost her 2300.00. Let me do some searching and see if I can find the post.

I really don’t know what the cost would be or how reliable the batteries really are…All I know is what I’ve been able to find on the internet. I do know a couple of people who own Hybrids and so far they haven’t had any issues with their batteries (or any other part of the vehicle for that matter).

If you can find something different about it please post…I’m very interested…I know it wouldn’t be the first time some car manufacturer skewed the numbers to make their vehicles seem more reliable then they really are.