Is battery life dependent on age or mileage? Help!

It's complicated. See this:
What is the Hybrid battery lifetime? | PriusChat

The challenge with such a low mileage car is that the battery likely sat without being charged for extended periods, which isn't too good for it (see #4 in above thread). I would try to buy a newer model with more miles for the same price.

 

welcome!
we don't have any studies, but lack of usage seems to be a problem. every battery is different though, because there are many usage and storage factors involved.
if the deal is good enough, and allows for potential repairs, it might be worthwhile.
otoh, if you don't diy, finding a good hybrid mechanic can be challenging, and dealers are very expensive.
my daughter has an '08 with 90k on it. she will be doing some long distance driving in the future, and i would like to see her in something newer.
a possible downside is scammers. can you find the definitive history of the vehicle, to make sure the odo hasn't been rolled back, no accidents, proper maintenance, etc.?

 

low miles does not mean a problem free car, I have found the opposite to be true... $8800 for any 10 year old car is insane IMO... unless its a 200 mph super car than Ill take 2

 

Like Kevin said above, it's complicated. And the simple answer is both. I've examined statistics on True Delta, and from what I could find, Prius traction batteries tend to almost universally last around 10 years and/or 100,000 miles without issue. At or around that point, some batteries will start to fail, and between 1-3% of batteries past either that number of miles or that age will fail each subsequent year or so. It has also been theorized that certain activities and environments are likely to degrade the traction battery faster, such as lots of hill travel, prolonged high temperatures, and leaving the car sitting for extended periods of time.

However, it is difficult to determine exactly what the most significant aspects are that contribute to battery failure for 3 reasons:
1.) most Prius traction batteries (easily over 85% total) last the entire operational lifetime of the car
2.) Toyota and the mechanic shops that replace batteries do not share their information with the public
3.) the people who post about battery failures on forums like this rarely share enough relevant information to make conclusions about what was the primary cause of the battery's failure.

 

I drive a 2008 Prius Tspirit in the U.K., purchased practically 4 years ago with 55,450 miles on the clock at the time of purchase.

As of yesterday night, it presently has 94,500 miles on the clock. It's put through the Toyota Hybrid Systems check every year at the dealers, and passes with no problems detected. They also extended the guarantee on the hybrid systems for another year when you service your car with them and take out this checkup. (Only up to 10 years over here, I think, but I digress).

My vehicle does a 36 mile round trip commute, 5 days a week literally all year round except at Xmas and two weeks in summer (when it still gets driven).

Given the relatively cool climate in the U.K. plus the fact that I unfailingly keep the A/C operational during hot summers, I fully expect my HV battery to last the full 180,000 miles (projected lifetime of a Gen 2 Prius as per the service book).
BUT.....Murphy's Law might well throw a curve ball at my Prius, and the HV pack might well give up the ghost next week! Highly unlikely, but entirely possible!

I'd be happy to get 150,000 miles before the HV battery fails. I'm aware I could even get over 250,000 miles before failure.

Regarding the target 2007 Prius for sale; it's HV battery's future reliability depends on how it has been used over the last 10 years. What climate has it been operating in. How hot or cold is that place? Hotter locations heighten the risk of HV battery failure. Cooler climes mean a generally longer battery life. Ditto with the location of use's landscape. Lots of hills or mountains could theoretically shorten it HV battery's life. Flat land? Longer life. How was it driven? How long does it stand unused per week? Was it garaged while standing, protected from the elements? Or was it standing in Nevada style heat, frying every day for 4 days a week?

Truth is, you might buy it and it'll be perfectly fine to 200,000 miles - because it's never really suffered despite the low mileage.

Or, it might have been a lemon from the word go, and someone has already detected one or two cells in the HV pack are about to go south and is trying to offload it before it pops its clogs.

It's all purely down to having precise information on this vehicles past. Or not, as the case may be.

Sorry about the rambling, but I thought my 2 cents worth might make a difference in your quest for answers.

p.s. Check it's long term history. If the mileage per annum has been equally spaced out, it might still be okay.

Why? Because the Gen 2 Prius is one heavily over engineered reliable workhorse! I still see 2003 and 2004 models plying the roads day after day over here. They're very tough hombres!


iPhone ?

 

Yes, on BOTH.

From the hundreds of posts on the subject and knowing a little about rechargeable batteries, the WORST thing for them is to sit unused for periods of time. Driving, even a little every day in 100*F+ weather is better than letting them sit unused for days, much less weeks or months at a time.

Also, it seems that mostly long distance trips are also sub-optimal for them, not really sure why, because the system should cycle the SOC some even under these conditions.