12 Volt Battery Issues

[AZdave]

Hi Everyone,

We own a 04 prius that we purchased in early 07. In mid O7 we repalced the 12 volt battery after an incident where the car just stopped in the middle of the road. According to the dealership, the computer system thought the car was out of gas(which it wasnt) and proceeded to discharge the battery. They fixed this. I cant actually remember why they had to replace the battery

Anyway jumping ahead 2 years: I have had to jump start the car on twice over the past 2 weeks. After the 1st time we thought that it was an overhead light that may have been left on over night. The car ran just fine for the next weeks until last Saturday. We were on our way to Flagstaff for the weekend. The car started just fine. We drove about 10 miles and stopped for gas. The car would not start. When pressing the power button for a couple of seconds, some lights would come on for a second and then nothing. When pressing the button and depressing quickly, the other electronics in the car would work fine(Air, Radio). We have the jump leads in the car and were able to ask a friendly passer by to help us.

I called the dealership(same one as 2 years ago) and they told me that its possible that its a bad battery. I explained that the battery was only 2 years old. He said that the AZ heat is very hard on battery life. Would a battery die after 2 years in Arizona? Before we left for the trip, I did have the car running idle with the air on high for 10 mins because we have a 1yr old. Would this affect the battery?

This evening the car is starting fine. I want to do some tests to figure this out and so I would like some guidance. Am I able to verify for myself that this is a bad battery?

It costs $275 including labor to replace the battery. For the battery alone its $165. Im going to call a different Toyota Dealership tomorrow morning to get a 2nd opiniin as well.

Thanks for any suggestions,
Dave

[efusco]

2 years is a bit premature for a battery to fail, but it wouldn't be unheard of. That said, it seems like something weird could be going on preventing the battery from charging properly (since it wouldn't start after the fill-up I wonder if it's a charging issue).

Of course, once it's drained once or twice they're never quite the same and you may well be due for replacement.

Don't pay anyone to put the battery in for you. It's very easy to do yourself. Yes, they are pricy, but at least pocket the $100 they wanna charge you for install.

http://www.techno-fandom.org/~hobbit/cars/prius-12V/

Also, several people have been happy using the Optima battery as a more durable choice...also a DIY job.
Optima Battery Installation

[AZdave]

Thanks for the super quick response.

We only have 50K miles on the car and this would be the 3rd 12V battery.

I forgot to add that about 3 weeks ago we had to have the invertor replaced on the car. Would this cause a drain on the battery in any way? It may just be coincidence but we have not had any issues with the car for 2 years and suddenly the invertor and battery have to be replaced?

[efusco]

Which inverter? It'll take someone with deeper tech knowledge than I have to answer the question of whether an inverter could lead to 12v issues...but my gut says "yes".

[AZdave]

Originally Posted by efusco

Which inverter? It'll take someone with deeper tech knowledge than I have to answer the question of whether an inverter could lead to 12v issues...but my gut says "yes".

It was an inverter water pump that failed.

[efusco]

Originally Posted by AZdave

It was an inverter water pump that failed.

So did the pump and the inverter require replacement? There are 2 or 3 inverters in the Prius. (MG1, MG2 (one or both likely candidates for you), and I think there's a DC/DC inverter for the HV->12v battery).

[AZdave]

afaik it was just the inverter. They told me that they were going to replace the old one with a newer model. I can tell you exactly how much it cost. $492

[qbee42]

If it was the inverter that supplies 13.8V to the DC bus, that would explain the dead 12V battery.

Tom

[AZdave]

So I just called Right Toyota and they told me that it was just the pump that was replaced and not the inverter.

I went ahead and ordered one of those Ultima batteries so hopfully that will resolve the problem.

[Frayadjacent]

2 years is short, but with an event like the interior light staying on that drained the battery down, it's life was probably reduced. Batteries don't like to be too deeply discharged. Sometimes getting to that state permanently alters it's ability to charge back up. Chemistries vary, though.