RichCapeCod wrote:We’ve had our 2019 Premiere for about two weeks, so, this is just a newbie observation. Should not the EV manufactures out there put a low 12v battery warning light/symbol in their vehicles?
Of course they should.
Follow-up: The car was plugged in for about 60 hours, about 45 hours of which was after the app said it was fully charged. Interestingly, the app said, "Keypass Disabled, Your vehicle's Battery Saver has disabled your connection. Please allow the vehicle's 12-volt battery to recharge and try again," well after it said it was fully charged. Yesterday, I unplugged it and got in to drive it to the dealer. When I turned it on, the icon that indicates it needs service came on, and it would not shift into reverse or drive. It was towed to the dealer. The tech at the dealer just called. He said that he had tested the 12 V battery, and it was good, and he found nothing wrong with the car. He said the battery was discharged when the got the car. He didn't offer an explanation for why it was discharged. It seemed obvious to me that the 12V battery was not getting charged as it should, assuming that it should be charging when the car is plugged in. They are going to keep it overnight and observe. The tech seemed fixated on the idea that something had been left on, but did not explain what could be left on to drain the battery. Surely the car is smart enough not to allow that.
Does anyone know for sure how the charging system for the 12V battery is supposed to work?
"He said that he had tested the 12 V battery, and it was good, and he found nothing wrong with the car. He said the battery was discharged when the got the car." This is a RED flag!! The 12 volt battery should never be discharged unless the battery is defective, something is draining the battery or the charging electronics are not working.
If the Bolt 12 volt battery charging function is anything like the Spark EV, then this is what I found that might help - I measured the 12 volt battery voltage on my 2014 Spark EV after the car had been powered off for a couple of hours. It read about 12.5 volts. Then I plugged the car into my L1 EVSE set at 8 amps and measured the voltage. It read about 13.3 volts. I removed the charging cord and, after a couple of minutes, remeasured the battery voltage. 12.5 volts. Then I started the car and remeasured the battery voltage. It measured 14.5 volts. I got similar results for my 2016 Spark EV using my L2 EVSE (240 VAC at 16 amps).
Numerous Spark EV electrical problems have been attributed to the 12 volt AGM battery and were corrected by replacing the battery. If the Bolt 12 volt battery charging function is like that in the Spark EV, ( same 12 volt AGM battery ) then the 12 volt battery only gets a small trickle charge when the car is plugged in. The main charging of the 12 volt battery occurs when the car is powered on and continues until the car is powered off.
I would suggest you get a good voltmeter and test the 12 volt battery for yourself; especially with the car powered off and then with the car powered on. If you do not see the voltage jump from 12.5 volts with the car powered off to about 14.5 volts with the car powered on, your battery is not getting charged. Check the 100A fuse at the side of the positive terminal or take the car back to Chevy, explain what you found and have them check the fuse and the charging electronics.
It really sounds like you have a blown fuse, a bad 12 volt AGM battery or a problem with the charging electronics. I would also suggest purchasing a BatteryMinder 2012-AGM battery charger and charging your 12 volt battery at least once per month for 10 hours or more - I charge mine overnight. BatteryMinder has an option that allows you to charge through the OBD2 port inside of the car and it works great. This is what I do for both of my Spark EVs.
Please keep us posted on your progress and solution(s).