Won’t start unless jumped (2008)

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Has the 12v battery ever been changed?

You can test it with a voltmeter, and there are jump points under the hood.

 

The battery is much smaller than a non hybrid battery and charges at a much lower rate. He is asking if you have checked the battery voltage using a voltmeter? Everyone’s first guess here is going to be have the 12v battery checked. It’s probably bad.

 

have you checked all the fusses?

 

Changed, not charged. Has the factory battery ever been replaced? If not, then it is well beyond its life expectancy. In numerous environments, even the first replacement would be near death by now.

 

It sounds like a bad 12v Battery. You could jump start again and drive to the Toyota dealership or another store like Autozone, Advance Auto or PepBoys to test the battery for free. They hook up a digital tester and tell you in a few seconds if it bad or not.

You can also check the date of the battery and if it is more than 6 years old replace it anyway. Since there is no traditional starter in our cars it is more difficult to detect a failing battery early. However, this is one of the most common reasons that stresses the hybrid battery.

The dealer is charging around $300 but I got one installed at pep boys for $160. Just make sure the technician installs the vent.

 

Please make sure if you must jump start the car your not connecting the jump leads directly to the 12 volt battery in the trunk.
Toyota provide very convenient and safe jump points under the hood. They address it in the owners manual.

Jump starting a G2 prius is very dangerous to your wallet.

 

If using the jump points under the bonnet, there is stil a chance there is something wrong with e.g. the ground of the battery in the back. But I agree that a failing 12V battery is most likely.

It (the 12V battery) is used to power up all computers (I have heard this needs about 20 amperes).
Once the computers are started, the 200V battery is switched ON and this in turn feeds the DC-DC converter to make 12V (between 14.1 and 14.4V in the Prius). So once started, it doesn't really use the 12V battery anymore (most normal cars don't either apart from it being a buffer&load needed for the working of the alternator).
The 200V battery is then used to start the engine when needed (and the engine, once running, can be used to charge the 200V battery, the software keeps the 200V battery always between 40 and 90% or so, so little to no chance of it ever being too low to start the engine (to recharge itself)).