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It's not about affordability, it's just no practical. You wouldn't want the main traction battery always connected. You might go to higher voltages for the types of things you mentioned. Something like 48V, but no one is talking about 400V.
The reason the high voltage battery is isolated while parking is safety, every time a car with a high voltage battery pack is parked the battery needs to be safely cooled and stabilized. The low voltage system is kept running to monitor the high voltage battery and insure that it remains stable. Some people do not realize the volatility that happens in an automotive grade lithium ion battery pack, but it is serious and must be monitored. Bolt EV battery fires are a good example, not a single Bolt caught fire while it was being driven, and coolant circulating, fires happened after charging, or while parked. These are times the coolant flow is stopped, and if a single cell overheats the BMS does not always sense it and restart the cooling. I have noticed my Tesla the cooling system often runs 20-45 minutes after the car is parked or charged, where our Audi E-Tron does not do this... In the Audi, when charging stops the the cooling system shuts down. I hope the later generation EV's have better monitoring, and sensors to babysit the high voltage battery pack, and fires should happen less often.
 

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GMC Sierra, Bolt, Sky, Mach E
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The reason the high voltage battery is isolated while parking is safety, every time a car with a high voltage battery pack is parked the battery needs to be safely cooled and stabilized. The low voltage system is kept running to monitor the high voltage battery and insure that it remains stable. Some people do not realize the volatility that happens in an automotive grade lithium ion battery pack, but it is serious and must be monitored. Bolt EV battery fires are a good example, not a single Bolt caught fire while it was being driven, and coolant circulating, fires happened after charging, or while parked. These are times the coolant flow is stopped, and if a single cell overheats the BMS does not always sense it and restart the cooling. I have noticed my Tesla the cooling system often runs 20-45 minutes after the car is parked or charged, where our Audi E-Tron does not do this... In the Audi, when charging stops the the cooling system shuts down. I hope the later generation EV's have better monitoring, and sensors to babysit the high voltage battery pack, and fires should happen less often.
The Bolt always turned on the cooling with high temps and having it plugged in, even when not charging. Last summer they did a software update so that it also runs even when not plugged in in high temps.
 

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you should always have truck or any ev plugged in 24/7 if at home just in garage its better for battery not worse

have 7 tesla over the years they always plugged in while in garage


Battery was over 90% when I left on vacation. All accessories were off and the truck was not plugged into the charger. I believe it is the 12V starter battery that is dead, not the drive battery.

Proof of what? Picture of the truck in my garage? That is easy. Proof that it is dead? Not so easy. The MyGMC app is not communicating with the truck.

I don't think GMs new technology is malfunctioning, but neither do I think it is reasonable for a brand new vehicle to have a dead battery so soon.
 

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I have a similar situation with my Hummer EV. Came home last night to a dead vehicle after 6 days sitting in a garage at 90% charge, not plugged in. Nothing was plugged in or turned on that may drain the battery. Manually popped the hood and put a high quality charger on it and it came to life completely this morning. I'm taking it to the dealership to evaluate the 12v battery. Some observations:

  • When the 12v is dead, the windows don't automatically raise/lower for opening the door. That's a problem!
  • There doesn't seem to be an unswitched 12v charger to plug a maintainer into, like the one on my C8. (If I don't find one, I'll hard-wire a battery tender plug like I added to the Porsche.)
  • 6 days is too short a time period for a 12v to die; I often park at the airport for over a week.
  • I was able to start the truck with the hood open (good), and even drive it, which means I could jump start if stranded.
  • A key fob was 30 feet away; could that be a contributing factor? I usually leave keys in my car so I gotta stop that.
 

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I have a similar situation with my Hummer EV. Came home last night to a dead vehicle after 6 days sitting in a garage at 90% charge, not plugged in. Nothing was plugged in or turned on that may drain the battery. Manually popped the hood and put a high quality charger on it and it came to life completely this morning. I'm taking it to the dealership to evaluate the 12v battery. Some observations:

  • When the 12v is dead, the windows don't automatically raise/lower for opening the door. That's a problem!
  • There doesn't seem to be an unswitched 12v charger to plug a maintainer into, like the one on my C8. (If I don't find one, I'll hard-wire a battery tender plug like I added to the Porsche.)
  • 6 days is too short a time period for a 12v to die; I often park at the airport for over a week.
  • I was able to start the truck with the hood open (good), and even drive it, which means I could jump start if stranded.
  • A key fob was 30 feet away; could that be a contributing factor? I usually leave keys in my car so I gotta stop that.
Thanks, all good info. Yeah, if there are just say a few hundred delivered and we are seeing a few instances of this already then it'll just continue to get worse until its a more known public fact/take on the new Hummer. "Oh those Hummer EVs you can't leave more than a few days without them going dead" I can hear in future.

Hopefully they can update the software or so to trim down the energy the truck is using while sitting unplugged, and/or proactive charge the 12v battery while sitting from the HV battery better, etc.
 

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2019, Chevy, Volt, Voltech with 7.2 kW optional Charger
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It might be a bad batch of AGM batteries....

However,

I've seen this issue happen on a few other EVs. It seems to be an issue of the computers waking to often to ping home/do diag checks or looking for the fob.

As the manual does state if you can, keep the EV plugged in so it can maintain the 12V battery.

Edit: I will mention that the onstar computers will always be on 24/7 in a low power state waiting for remote commands or to send data to the cloud/app.
 

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Hope they get this figured out. I travel a lot for work and leave my vehicle at an airport for 4-6 days at a time. I'd hate to fly back home and then be stuck at a parking garage because the 12v battery died.
 

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Mine is now back home and working good. GM diagnosed the problem and traced it back to an over-the-air update that was trying to run continually, eventually draining the battery. They pushed a few software updates, with more to come OTA, and it resolved the battery drain issue. There was nothing wrong with the 12v battery or any hardware; just software updates needed.
 

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I have a similar situation with my Hummer EV. Came home last night to a dead vehicle after 6 days sitting in a garage at 90% charge, not plugged in. Nothing was plugged in or turned on that may drain the battery. Manually popped the hood and put a high quality charger on it and it came to life completely this morning. I'm taking it to the dealership to evaluate the 12v battery. Some observations:

  • When the 12v is dead, the windows don't automatically raise/lower for opening the door. That's a problem!
  • There doesn't seem to be an unswitched 12v charger to plug a maintainer into, like the one on my C8. (If I don't find one, I'll hard-wire a battery tender plug like I added to the Porsche.)
  • 6 days is too short a time period for a 12v to die; I often park at the airport for over a week.
  • I was able to start the truck with the hood open (good), and even drive it, which means I could jump start if stranded.
  • A key fob was 30 feet away; could that be a contributing factor? I usually leave keys in my car so I gotta stop that.
[/
How did you pop the hood (frunk) when the 12v battery is dead?
 
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