[Ewillmore]

We have had our 2018 Bolt for less than three weeks. Yesterday it got towed back to the dealer after everything shut down. While I was driving, I got a message that the AC had lost connection. Then the alert lights and messages started: airbags, tire pressure monitor, theft deterrent, and on. Lost turn signals. Drove it to a parking lot and turned it off. And then it wouldn’t turn on again.
Had to have to dragged out of the spot in park to winch it up on the truck.
It had been fully charged.
Any insights?

 

[XJ12]

12 volt battery may have died.

 

[Ewillmore]

While driving? Is that possible?

 

[XJ12]

While driving? Is that possible?

My Oldsmobile Aurora left me stranded once from the battery suddenly dropping voltage to the point that all the accessories died. Pulled over and car was still running but I couldn't accelerate.

There's been many reports of early 12 volt battery failures due to dealers letting the cars sit too much on the lot. Could also be something more mundane as a loose battery cable.

 

[Sean Nelson]

While driving? Is that possible?

No, if the issues started happening with the car turned on (and assuming that the high voltage battery had plenty of charge) then IMHO it's not likely to be the 12V battery. When the car is turned on 12V power is supplied from a DC-to-DC converter powered by the main traction battery.

There's always the outside chance that there was some problem with the DC-to-DC converter and that caused the 12V battery to run down, but it seems like a less likely scenario in my mind.

 

[GregBrew]

I'd bet aux battery.


That's been the cause of probably 90% of weird behaviors with EVs for the last twenty years.

 

[DucRider]

No, if the issues started happening with the car turned on (and assuming that the high voltage battery had plenty of charge) then IMHO it's not likely to be the 12V battery. When the car is turned on 12V power is supplied from a DC-to-DC converter powered by the main traction battery.

There's always the outside chance that there was some problem with the DC-to-DC converter and that caused the 12V battery to run down, but it seems like a less likely scenario in my mind.

The power from the DC-to-DC converter is fed thru the 12V battery. A bad battery (shorted cells, etc) may pass much less than the required voltage on to the car systems. Vehicle computers getting less than 11V often shut down completely and would match the symptoms described by the OP.

 

[drdiesel1]

I'd bet aux battery.


That's been the cause of probably 90% of weird behaviors with EVs for the last twenty years.

There is no such thing as an "Aux Battery" in a Bolt. You have the 12 volt battery and the HVB.

 

[Ampera e]

The power from the DC-to-DC converter is fed thru the 12V battery.

Technically speaking: no.

The DC/DC converter and the battery are hooked up in parallel, not in serie. Otherwise, the voltage level on the 12 volt circuit would be 24 when the converter was active.

But if the battery had extremely low internal resistance (not high), it would short circuit the 12 volt system as a whole and disable the car. Even with the DC/DC converter active.

 

[Ampera e]

There is no such thing as an "Aux Battery" in a Bolt. You have the 12 volt battery and the HVB.

What is your definition of an AUX battery? Yuasa distinguished between starter batteries and aux batteries. Not having a starter in our car (and thus no starter battery), this would make our 12 volt battery the ultimate aux battery.

https://www.yuasa.co.uk/info/technical/auxiliary-back-batteries-explained/

 

[beeguz]

A loose battery cable on the battery under the hood can give you all those crazy lights, and fail to contact when you wanted to power up.


Call it what you want the without the 12V battery that is located under the hood, the car won't work.

 

[GregBrew]

There is no such thing as an "Aux Battery" in a Bolt. You have the 12 volt battery and the HVB.

For the last twenty years (since even before the EV-1), what was called the "starter battery" in ICE vehicles, has been called the "auxilliary battery" in EVs, because there was no ICE to start. The larger battery for vehicle propulsion has been called the "traction battery". Not all EVs use a high voltage for the traction pack. I've seen some at 48V.


You're forgiven...

 

[Ewillmore]

Well, my Bolt has been at the dealer since Wednesday night. So four business days. No word. As of yesterday, I was Bolt #4 to be serviced by the one EV tech. Since even the recall updates I read about seem to take only an hour or two, what are they doing to those other Bolts? How is a week-old car not a priority? They are treating me like I am the issue, not my dead car. I’m not seeing reports of this happening on anything I am reading (I’m just getting started with the whole EV experience).

 

[drdiesel1]

What is your definition of an AUX battery? Yuasa distinguished between starter batteries and aux batteries. Not having a starter in our car (and thus no starter battery), this would make our 12 volt battery the ultimate aux battery.

https://www.yuasa.co.uk/info/technical/auxiliary-back-batteries-explained/

It's not called an AUX battery in GM's world. They made the car, so it's a mute point
to try and prove otherwise. Call it what you like, but you won't find it under AUX on any
GM parts listings or in the repair manual. Have fun!

 

[Ampera e]

It's not called an AUX battery in GM's world. They made the car, so it's a mute point
to try and prove otherwise. Call it what you like, but you won't find it under AUX on any
GM parts listings or in the repair manual. Have fun!

Nobody tried to prove GM called it an Aux Battery. You claimed the Bolt didn't have an Aux Battery, which (looking on what an Aux Battery really is) appears not to be true. If GM calls the driver door "the left side front door" in their parts listing or in their repair manual, does it mean the car does not have a driver door?

 

[Dimitrij]

It's not called an AUX battery in GM's world. They made the car, so it's a mute point
to try and prove otherwise. Call it what you like, but you won't find it under AUX on any
GM parts listings or in the repair manual. Have fun!

A mute point as in "shut up"? :laugh:

 

[lookieloo]

Speak with your big heads, gentlemen, not with your little ones. And the word should have been moot, not mute.

 

[Sean Nelson]

If GM calls the driver door "the left side front door" in their parts listing or in their repair manual, does it mean the car does not have a driver door?

drdiesel1 is a GM tech, so he's used to speaking in fairly precise language about car components because any ambiguity can lead to mistakes.

But most of us are not and are used to speaking in more generic language. And I certainly agree that "aux battery" is a perfectly cromulent term for describing the Bolt's 12V battery. From my perspective it seems pretty unambiguous.

 

[drdiesel1]

A mute point as in "shut up"? :laugh:

Nope! Wouldn't tell anyone to shut up. Just splaining, Lucy!

 

[drdiesel1]

Nobody tried to prove GM called it an Aux Battery. You claimed the Bolt didn't have an Aux Battery, which (looking on what an Aux Battery really is) appears not to be true. If GM calls the driver door "the left side front door" in their parts listing or in their repair manual, does it mean the car does not have a driver door?

I might! >