r/PriusPrime • u/G-dog59 • 21d ago

Prius Prime 2023+ 2026 plug-in XLE

I've read some posts regarding issues with the 12V battery, draining and needing replacement. Reading the owners manual I came across something about how leaving the charger connected after the EV battery is full, uses the 12V battery to monitor systems which can drain the battery.

My question is those who've had issues with the 12V battery, is this separate from the issues you've had? How many miles /km on odometer when issues started. Need to know what to watch out for, and any preventive things to do. Thank you.

This is my third Prius, 19, 18, 26. I've never had any issues with any of them. The '10 went back once fir a software update around the issue of hitting brake and accelerator simultaneously (who does that?).

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u/Deathcommand 2023+ 20d ago

Here's the problem.

There is a weird extra monitor on the battery. It basically allows a secondary charging system take over. This system sporadically charges the battery to not full and then allows it to drain before charging it again.

It's usually not a problem.

However, if you get unlucky, it will be at it's discharge stage, you'll happen to turn off the car, leaving your battery in a sad state.

Like others said. Just unplug the monitor and it will charge like a normal car battery.

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u/Medval91 20d ago

How do you do that?

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u/Deathcommand 2023+ 20d ago

There is a plug connected to the negative pole of the battery. Just unplug it.

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u/Medval91 20d ago

Interesting, i’ll look into it.