question on 2008 prius

Based on the limited publicly available statistics we can access (mainly from here and True Delta, although an occasional Consumer Reports article also helps), almost all Prius batteries last at least 10 years and 100,000 miles without problems. After that point, failure rates are approximately 3% for an 11-14 year old car, and increasing up to 15% for the oldest Prii (that's the plural of Prius! ) on the road today. So if you buy a 10-year-old Prius, you've got a roughly 3% chance that the battery will fail in the next 4 years, up to a 15% chance that the battery will fail in the 3 years after that, and (assuming an exponential decay rate) most likely a 50% chance the battery will fail in the 5-6 year period after that.

So basically, if your Prius is:
less than 10 years old, your battery has less than 1% chance of failing
10-14 years old, your battery has approximately a 3% chance of failing
15-17 years old, your battery has up to a 15% chance of failing
18+ years old, your battery could fail at a coin flip (50%)

So it depends on how long you plan to have the vehicle. I'd feel comfortable driving a well-maintained Prius that's up to 14 years old without question, so if you bought a 2008 Prius now, that gives you a very good chance of 4 years of ownership, and a good chance of up to 7 years of ownership before the battery is likely to be a concern. Of course, some batteries will fail early, and some will last way longer than anyone expects, but the averages I listed (except for cars over 18 years old, since there aren't any of those around yet) are accurate to the best of the collective reporting of True Delta and Prius Chat based on my analysis.

 

Mine is still ticking and it is an 08. At 164k miles. Youre in luck.

Posted via the PriusChat mobile app.

 

heat plays a large part in early hybrid battery failures. national statistics are skewed by northern vehicles.
i wold start putting aside $3-4,000. for an eventual new battery.

 

we've never seen anyone or anything able to predict battery longevity, not even roughly. there is a self made test by a pretty bright guy here, but i'm not sure of the predictive accuracy.
sorry, i can't help with the graphs and charts, hopefully someone more knowledgable will chime in.

 

yes, i'm trying to think of it, or the posters handle.

 

Congratulations on your Prius, I hope you enjoy the car.

If you keep it for several years, you'll probably have to fix some things. They may or may not be your battery. Every new owner seems to spend inordinate effort trying to figure out when the battery will fail (that included me, first time I bought a Prius), and nowhere near as much time or effort doing the same speculations about the other wear items in the car.

I bought my first Prius when it was seven years and 125,000 miles old, and drove it to fifteen years and 234,000, during which time I replaced two wheel bearings, some brake and suspension parts, and one door hinge. The battery never gave me trouble, though I understand the next owner did replace it.

I'm on my second Prius, and I think by now I am over the urge to agonize over my battery any more than over any other wear aspect of the car. Just put some money to a repair fund, for whatever repairs happen to come. The one early sign of anything I've seen in this car so far is a slightly reduced compression in cylinder 2.

-Chap

 

Just a quirk of my particular Prius. Don't stress about low compression in your Prius, unless you happen to measure low compression in your Prius.

I like to take some basic vital stats as soon as practicable after buying a car, so I have a baseline to compare to later. Right after I bought this one (at about 110,000), I started by measuring the brake linings, quick and easy to do.

Measuring compression in a Prius is a PITA, so I put that off until doing my spark plug replacement at 120,000 (which is also a PITA, for all the same reasons). So that's when I took my first, baseline, compression measurements, and noticed that while 1, 3, and 4 came out with virtually identical numbers (excellent!), 2 was a bit lower, though still within the tolerance for variation between cylinders. The engine runs smoothly with no codes and no sign of any trouble, and I wouldn't know about this any other way than taking the measurement. It is just a single fact about my particular Prius, for me to keep in the back of my mind, possibly to test again in a few years and see how it's changed.

If you feel like copying any of how I maintain my Prius, copy the "take early baseline measurements of things and compare occasionally" part. Don't copy the worry about any particular measurements I get on my car. Remember the measurements you get on your car.

-Chap

p.s. I see you have a Gen 2; I think compression measurements are less of a PITA for you.

 

Your charts look good. All module voltages (first chart) are very close to each other during the discharge portion of the test. The delta V between modules looks to be about 0.1v in the later chart. That battery appears to be in pretty good shape. The delta V is an important indicator. As the battery wears and becomes unbalanced, that number will increase. You'll also be able to see it in the first chart, as the chart lines (module voltages) will start to separate from each other instead of almost laying on top of each other.

Here's some graphs from a load test I did on a Gen 2 built with Gen 3 modules today. You can see in the first screen capture that the starting SOC was about 65 and about 45 at the end of the load test.

 

Pretty sure @bisco was talking about the @S Keith thread below:

How to test HV battery state of health on your Gen 2 (answer) | PriusChat

Wish there was a way to convince 'S Keith' to come back and grace us with his presence once again

 

exactly, thank you!

 

Before you return the car, EJS279, consider this: BU-1002a: Hybrid Electric Vehicles and the Battery – Battery University

There was a study comparing hybrid batteries when new and at 160,000 miles. The above link has a graph. Prius batteries in the study were only 39% at 160,000 miles but there was minimal impact on fuel economy.

If battery wear was linear, then 45% after 9 years means the battery will likely last another 7 years before it dies. Are you saying 7 years is too short a time to own your Prius? It's longer than most people own cars today. I'd urge you to reconsider.

 

That doesn't sound bad at all for that age. What you're seeing appears to be reduced overall capacity because of the cells gradually getting out of balance. Easily remedied with a Prolong Grid charger, which helps extend the life of the battery. I've been using one for years and many others do as well. I learned about it from the shop where I bought my last four Prii where they specialize in hybrids and electrics. Many threads here about it.

 

While MovingRightAlong makes a good case, Toyota has been modifying the battery with each generation, so the jump in older Prius battery failures may be because of an older design, rather than just age of the batteries themselves. (most likely both)

The same can work the other way, the Gen 4 chemistry does not build on Gen 1 to Gen 3 chemistry, so the history of past Prius is no indicator of Gen 4 longevity.