WHY NO 12V Battery Charging Instructions in Owners manual ?

Mostly because the designers reasoned that if you can manage to kill your 12V battery, you would also kill your HV battery if allowed to do so. Recharging or replacing the HV battery is a lot more expensive.

Tom

 

What seems like a long time ago, when they were kicking around the idea of introducing higher voltage DC in a car, the big concern was safety. You have mechanics that are used to 12V and may get careless around higher voltages. My first thought was that JimN had a good point and then I remembered those old articles that I probably read in IEEE Spectrum or similar trade magazine.

They've isolated high voltage DC to a specific area and keep the rest of the car at a voltage that we are all used to.

 

I'm going to go with the safety argument; when the car is off, they want the HV battery to be completely disconnected. That battery can source lots of volts and amps, and you don't want to be guessing whether it's connected to the electrical system or not. Qbee's reckoning is good as well.

 

12V charging from the HV battery could be done without exposing HV in the rest of the car if a small DC to DC converter were located inside the HV battery box. In that case only 12V would be present when the car was powered down, but the HV battery could be used to maintain the 12V battery.

It's not really a safety issue or one of protecting the HV battery, but one of cost and complexity. If you don't want to add cost and complexity, then safety and HV battery health become factors.

Tom

 

My owners manual has detailed procedures listed for jump starting was reading them the other evening. also details how disconnect the jumper cables... in reverse order.