I was doing some work inside the Bz and had the radio going. The system would prompt me a few times every 30+ minutes that the car was going to shut down. I must have let it shutdown a few time and put it into accessory a few times. Maybe 3 hrs of this. Went inside for lunch and then came back out to go somewhere.
I attempted to start it up and, no-go. The dash did a bit of blinking of lights and then got a "Brake waring failure" on the info screen. When I had my Prime, it would do this when the 12v battery was flat, so I understood this behavior. I pulled out my trusty digital Jump Starter, and the Bz turned on. Now the "Brake warning failure" is still lit. Ugh. Going have to take it to the dealer to clear the codes and give me a good bill of health.
Since this is not going to be the first time I do this (hazard of my job), I needed to read into how the Bz charges the 12v battery. The vehicle will charge the 12V system when the traction pack is engaged. So, like vehicles of old, you need to go drive it. The big question here is can I charge the 12v battery using a battery charge ? Do I need to disconnect the battery from the car to charge the battery? Most EVs are always on, so I think that is an important question to answer I charge it that way.