1998 Prius Battery Life

There's a lot of Fear, Uncertainty and Doubt being circulated about the Prius battery packs, old and new. Some of it is Toyota's own fault (people confuse warranty length for estimated Mean Time Between Failures; the two are not necessarily synonymous). Some of it is ignorance from people who hear the word 'Battery', remember how much trouble they have keeping their cell-phone well charged, and lose their nerve. And some of it is just willful propaganda.

Anyway: the pack on the 2004 is warranted in the United States for 8 years or 100,000 miles. This suggests to me that A] Toyota does not expect to actually be called to account for this very often (meaning they believe in the battery technology they've chosen) and B] that they're hedging their bets to prevent lawsuits, by making it clear that if they guessed wrong, they'll make good on it.

Because the truth is...the Prius is on the cutting edge of using batteries in cars this way, and nobody really knows, empirically, how long they'll last under this duty cycle. The oldest Prius on the road (1997) is younger than the length of that warranty.

That said: the statement 'we warrant this battery for at least eight years' is not the same as saying 'we expect this component to completely drop dead at eight years and three seconds'. It's a statement that any battery that fails *earlier* than eight years is definitely buggy, and therefore Toyota will acknowledge the fault and replace it.

My understanding is that there is no widespread panic over battery packs from even the early-generation Prius you're talking about, despite the fact that the oldest of them are now seven years old. Certainly, there have been no large-scale reports of issues with the newer models. But again...no battery has actually been deployed for the full length of the 2004 Prius' battery warranty. So nobody knows for absolute certain!

However, if the car is still running well, and there's been no significant change in how long the battery holds a charge (obviously, only its current owner will know that, so you'll have to trust them!), I'd guess that you don't have much to worry about.

 

The 2001 Prius Classic in Taxi service here in Vancouver had over 320,000KM's on it and it was still going when Toyota took it back for inspection and report.

 

It should also be noted that according to Toyotas web site, they have never had to replace a failed battery yet. (I.e. Failed in use.)

I can remember exactly where I read it, I think it was Toyota Japan.