I've read a lot of posts where people have allowed the little 12 volt battery to get discharged somehow and shortened its life. I assume the Prius vee is the same as other Prii in that the traction battery keeps the 12 volt battery charged. There is no alternator tasked with charging the 12 volt, just the two MGs that charge the Traction Battery. If that's correct, then why does it hurt the 12 volt battery to (e.g.) leave a light on? How can it run down the 12 volt battery and damage it but not hurt the traction battery?
The Traction battery is only energized when the car is in Ready mode.Most damage happens when the car is off.
I see, the traction battery goes off-line but the 12 volt remains on-line. So, if I had left an interior light on all night (and I'm not saying that I did), that wouldn't be as forgivable as I'd hoped. Thanks Jimbo
Is there a link to some information about what exactly is powered by the 12v battery? I know from reading the description of the Hybrid Synergy Drive that the MG1 is responsible for starting the ICE.
There are very few items NOT powered by the 12 volt system. The air conditioning compressor, MG1, MG2, and the inverter are powered by high voltage. So far as I know, everything else is 12 volts.
I still haven't figured out the requirements for the PTC heaters to be activated. Single digit tempts, full HV battery, max heat demand both auto and manual, cold soaked ICE, and I've only had them come on once. I knew they were on due to the smell and cabin heat being produced with an ice cold ICE. They are a great idea, but I wish I knew how to activate them at will.
Yes, there are relays that open when the car is shut off. These relays physically disconnect the high voltage battery from the rest of the car. When you try to turn the car back on, it uses the power from the 12V battery to close the relays to reconnect the high voltage battery. If you don't have enough power left in the 12V battery, then the car can't close the relays and therefore can't draw any power from the high voltage.
