Okay. Who HASN'T had a 12V battery issue with their 2023-24 Prime?

What about those of us with non-Prime HEV models? My 12V drains quickly. After driving, it never charges to above 12.35. Then in 2 days of sitting it will be down to 12.06 or so. First scheduled maintenance will be in July. Hopefully they'll have a solution.

 

Has your dealer installed a tracker?

 

I had some serious issues, but nothing since I installed a battery maintainer. I was unable to start the car once, while leaving it parked overnight at a hotel. Since then I've carried an extension cord and made sure to plug in the maintainer overnight.

I also have an auxiliary battery, like on a camper. It fits nicely into the space near the left rear fender. It's connected to the main 12V battery through a VSR isolator, which prevents the auxiliary battery draining when parked. The Voltage Sensitive Relay (VSR) cuts in at 13.3 volts and cuts out at 12.8 volts to ensure the primary battery is always charged and ready to start the vehicle.

If the auxiliary battery goes dead from running the drink cooler overnight, it only takes less than an hour to charge it up again through the isolator connection. I have also rigged a heavy duty bypass switch around the isolator, with a 30 amp fuse, in case I need to "boost" the primary battery. So far, the bypass current has never exceeded 10 amps.

 

having to keep a maintainer on it is a real plug for toyota engineering

 

I went on travel for exactly two weeks and when I returned from our flight the battery was too low to start the car. Unfortunately it never gave me a clear indication of why it wouldn't start, so I kept trying until the battery was well and truly dead. I find it very unreasonable that an otherwise regularly driven and maintained new car can't sit in a long-term parking lot for two weeks in moderate temperatures and humidity without draining completely. In my mind, that's a serious design or engineering flaw.

 

Which point for the -negative connection did you end up using?

 

There's a youtube channel based in Japan that did some reporting on the rear door issue. As it happens, the channel also posted a recent video on what I assume is the 12v battery issue. I'm relying on the auto-translate, so if there's a Japanese speaker on the forum, maybe they can have a listen?

The translation refers to the battery as the auxiliary battery, which I assume is the 12v. The channel believes a recall will happen for this issue at some point.

Apparently the 2 middle cells of the battery are getting damaged. They could be getting damaged simply via the installation of the battery in the car...something about a protrusion in the Prius that is impacting the battery? Or maybe the cells are just defective. Anyhow, it's interesting to see someone based in Japan also reporting on this issue.

 

@Salamander_King is fluent in Japanese.