12 volt battery overheating

This is the first time anyone has posted about something like this... First step is to measure how much voltage is being sent to the the 12v when car is in ready mode with a volt meter.

Or simply hold down the display button next to your screen while turning the headlights on and off several times, which will give you a white screen with menu of buttons to push and one of those will tell you how much voltage is being sent to the 12v.

 

No aftermarket wiring at the battery? No codes? My guess is the fusible link or connections on the positive side of the battery are bad. Otherwise it could be severe over voltage which would come from the inverter. Or an excessive current draw that was close to the battery. I would not fool around with this unless you know how to use a meter and dc current clamp. A thermal imager would be handy as well.

 

Overcharged or loose connections. Measure the voltage with ready on. If it is more than 15v the DC to DC inverter is faulty.

Also check voltage drop between negative post and chassis, plus between positive post and the positive access point in the engine compartment. If more than 0.5v then there is a loose connection or corrosion.

 

The rotten egg smell is likely from hydrogen sulfide. In low concentrations it just smells bad, but in high concentrations it can be hazardous or even lethal. The good news is that the smell is easily detectable at far far lower levels than will cause adverse health effects, like about a 500X ratio.

The bad news is that it is too commonly lethal for workers in enclosed spaces, and is known to have been lethal in a car with 12V battery inside the passenger compartment, with a severe charging system malfunction.

If the battery is smoking, don't drive or stay inside the car.

 

The other bad news is while the smell is easily detectable at far far lower levels than will hurt you, at higher levels it starts to smell sweet instead of rotten-eggy, and at still higher levels it knocks out the ability to smell it.

 

Welcome to PriusChat!!

If you have to jump the 12v battery to start the vehicle, then you likely need a new battery or have a bad 12v connection.

When was the inverter coolant pump last replaced (# of miles ago) ?

Do you have any warning lights being displayed on the dash?

FYI : you're moderated until you've posted 5 times.

 

Your post is a first. Which may mean its probably something very whacky.

Be aware there is a specific cable plugged into the 12 battery positive post fuse assy that the inverter uses to monitor the actual battery voltage. Its a sensing cable. If that is not plugged in it may over charge the battery.
I think.....

Here's a picture of the assy the wire in question is the little thin white cable into the white plug that's uses the 5 Amp fuse right next to it. Check the cable is plugged in and the little 5 amp fuse is not blown.

The fuse may have popped if there were any shenanigans with the battery it replaced.