2018 Prius c Early Battery Failure

Hey all,

I've been lurking for a while and have gleaned some really helpful info from this forum. Had something come up this week that I thought would be worth sharing and figured I'd pay it forward a bit. I could only find one other post on it and the mechanic seemed equally surprised.

I have a 2018 Prius c with about 87k miles on it. Bought it used from Carmax at about 69k. Only issue I previously had in those 18k miles I've owned it is both rear wheel bearings failing - they got super loud like a jet was over my car before being replaced.

Last weekend I drove about 400 miles round trip to Portland, and while city driving there I thought I noticed the car hesitating on acceleration a bit once or twice, but it didn't seem too alarming at the time as I couldn't replicate the hesitation when I tried. Highway driving there and back seemed fine. I got home Sunday night and didn't drive until Tuesday. I got in the car to run errands Tuesday night, let it warm up, and drove it toward the parking garage exit when suddenly my check engine light came on along with a hybrid system failure and pre-collision system failure warning on the dash. I pulled the car back into a stall immediately and turned it off. Tried turning it on again to see if that was a glitch, and nope, CEL still on. The engine went straight to ICE (no 5-10 sec delay) after turning the key and it sounded really rough. Arranged a tow to the local Toyota dealership service department the next day.

Dealership called back this morning and said the hybrid battery failed. It's under warranty, so they're putting in a new one for free. On one hand that's great, I dodged a bullet and am happy that I'll have a fresh battery. Also glad the service department could figure it out right away and were honest about it, it's my first time going there and that sure is a good sign. But on the other hand isn't it somewhat odd to have a battery fail on a 6 year old Prius under 100k miles? As I said before, I couldn't find many cases of people reporting that happening, and my assumption is that these batteries should last 8-10 years minimum and well over 100k miles.

Anyways, it is possible for a battery to fail this early I guess, although I have absolutely no idea what caused it. I drive a fair amount of both city and highway, and I never really go more than 4-5 days without taking it for a 20+ minute drive. I also keep the intake filter in the cabin clean - I've been cleaning it every 3 months since I have my dog in the car sometimes.

Curious to hear if there are any guesses as to why this happened, especially if it's something that's within my control in any capacity.

 

I noticed them starting to make some noise around 75k miles, and probably got progressively worse over the next 6-8k before I had them changed. I kind of was a frog in the boiling pot so to speak and didn't really notice how bad it had gotten until my dad rode in my car and went "ok, something is definitely wrong, I thought the Prius was supposed to be quiet". My ears were ringing after a few of the drives before I got it done, so it was probably pretty bad. Didn't notice any performance issues, just the noise. After having them changed it was a night and day difference.

Unlike for the battery, there were a lot of posts about wheel bearings failing early here, and I think you're right that something changed with respect to the durability of them. The best guess I have from what I gleaned when looking into why mine failed is that they're actually built differently, at least on these cars. I don't remember the specifics but the Prius definitely has different bearings than, say, a typical sedan from the early 2000s.