2008 Prius with possible 12 volt battery issue

i would ask them to test it, and show you the results. it's either a bad battery, or a phantom drain.

 

if it's a short in the windings, you'll need a replacement trans. but i'm not sure how the tranny would affect the 12v, it's the hybrid battery through the inverter that keeps it charged.

agree, sounds like a poor dealer.

 

The c2318 code sets every time a Prius 12v battery is low. We see it all the time and usually I asked a customer if they've jump-started the car in the past year and they say yes. It's not a code to anybody normally pays attention to, but when we see it we test the 12 volt battery. That's the root cause of the problem there's not something else going on in the transmission. It sounds like you just need to find somebody who really knows these cars. That being said I have a customer in my shop today that drove here from Seattle for us to fix their Hybrid battery.....

 

congrats!

 

Let's hope so.

Just to be clear though, it must be WELL over 12 volts to be considered "good".
The resting voltage of the battery without the car running (not in ready mode) needs to be at least 12.6; usually a bit more at 12.8.
When running, it should be at least 13.4, since that is about the voltage that is needed to "float" the battery and keep it from discharging.

A reading of 12.00 volts actually indicates that it is about 50% discharged.

Since you have had trouble with it, it would be a REALLY good idea to have that new battery manually charged with a small charger overnight. It is NOT necessary to disconnect or remove the battery to do that.