Not even a year and a half in and at 20K miles..... Been fine and then this morning wouldn't start, all kinds of lights and brake pedal pumping on it's own. Towed to dealer. Tested and battery fail, warranty replacement scheduled. We were heading up to the mtns today so ended up taking one car with all kinds of stuff loaded. It wasn't a scheduled appt but they are fast tracking it. While It's there til probably Monday I decided it would be a good time to get the 2nd key fob(I've had a letter for months now) and sync up the TPMS on the after market wheels. Cabin filter replacement too. Oh well for work and clients....it's ski time.
This is a common experience for many Prius and Prius Prime owners. If you want to see this coming a little in advance, and think about a battery replacement quicker with a scheduled appt at toyota, you might get a BM2 device and monitor the resting voltage of the battery with a phone app often at the beginning of the day (after the battery has been resting over night) and before putting the car in Ready mode. If you see a downward resting voltage that approaches 12.3 v or less, make a service appt and have the dealer do a battery test.
What i see in the Prime threads is that this is a result of both an insufficient 12v battery and the car's software not charging the 12v sufficiently. If the car's software is the problem, shouldn't a revision be part of a service update?
Prove the software is at fault. I've yet to see anyone provide evidence that it doesn't charge the 12v properly. The AGM battery thread and their monitoring pretty much summarizes the experience for most people.
Yes Randy I see a new battery too I will be researching this very carefully Funny after a 100% down and charged up 12.4 v with meter
Isn't conventional battery death at 18 months some evidence of a problem with the battery and recharging? My understanding of the Prius is that the 12v recharging is controlled by its software. If a new and better battery gives better reliability, that's great, but if a charging pattern of the battery Toyota uses gives an abbreviated life and poor reliability, that's a failure of that system. If it can be fixed with a software update that's free to me and lets me use ordinary lead acid batteries, that seems easier for most owners.
there was a TSB for a small software update if someone came in with a bad battery, but there may well have also just been a batch of bad batteries. The Prime's additional electronics and 12v draw probably just happened to make the batch more visible sooner in online boards like this one. And the regular prius is catching up now that they're getting older. Its almost always a 2023 model when I see these posts pop up. My 2024 battery has only died once because I was dumb and put it in accessory mode by accident one time. But never before that.
