bolter
Posts: 24
Joined: Sun Nov 26, 2017 8:51 pm

Re: Dead Car, Dead 12V Battery

Mon May 20, 2019 4:16 pm

I jumped my car twice. The first time, when it was completely dead, it woke it up and allowed me to charge it. I tried it again a second time after discovering that it was still undriveable after charging. I verified for myself after getting it back from the dealer that the 12V battery gets charged when it is turned off and not plugged in by checking the 12V battery voltage at intervals. It increased from 12.45V to 12.66V, which could only occur if it was charging or had been charged.

When the service manual arrives, I'll find out for sure what the expected charging behavior is.

DanDietrich
Posts: 13
Joined: Wed Nov 22, 2017 9:37 pm

Re: Dead Car, Dead 12V Battery

Mon May 20, 2019 9:57 pm

Try checking it while it is plugged in. I'm curious to see if it is charging then.
Dan Dietrich - currently own a 2014 Leaf, 2012 Prius V, and a 1984 F-250

bolter
Posts: 24
Joined: Sun Nov 26, 2017 8:51 pm

Re: Dead Car, Dead 12V Battery

Tue May 21, 2019 1:55 am

DanDietrich,

I checked the 12V battery voltage with the car parked in my garage and turned off. It was 12.45 V. I then checked it at intervals. Two hours later it was 12.66 V. Clearly, either the 12V battery was getting charged or had been charged in the interval because that's the only way the voltage could increase.

SeanNelson
Posts: 1444
Joined: Tue Jul 05, 2016 2:43 am
Location: Vancouver, BC

Re: Dead Car, Dead 12V Battery

Thu May 23, 2019 4:11 pm

bolter wrote:...I told the man at the service desk that I was concerned about a safety issue, i.e., that, if the 12V battery went dead when I was driving, would it be dangerous? Would I lose brake function? Would the brakes lock up?

The 12V battery is there to get the car "booted up" when it's turned off and the high voltage battery is disconnected. Once the car has been started and the "Ready" light has turned on, all of the 12V power comes from an inverter powered by the high voltage battery (it's actually something more like 13.5 or 14V). So there should be no risk of the car stopping because of 12V battery issues. The only problems you should see from a bad 12V battery would be the inability to start the car and the potential for a bunch of weird error codes being thrown during the startup process as the car's systems start to draw power - that can cause a weak battery's voltage to dip until the high voltage inverter comes online.

The runaround you're getting suggests that the dealership simply isn't familiar with how EVs (and hybrids) handle the 12V battery, it's got a very different usage and charging strategy than a conventional vehicle. If I were you I'd try to escalate this to GM customer service. The dealer should simply replace your 12V battery, but they may need some escalation in order to get GM to pay for it under the terms of the warranty.

SparkE
Moderator
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Location: SF Bay Area

Re: Dead Car, Dead 12V Battery

Fri May 24, 2019 5:36 pm

Recent post on this same subject:

viewtopic.php?f=10&t=8500&start=10#p33784

bolter
Posts: 24
Joined: Sun Nov 26, 2017 8:51 pm

Re: Dead Car, Dead 12V Battery

Fri May 24, 2019 7:22 pm

Thanks, SparkE. One difference between my experience and the one described in that thread is that his car was left unplugged for a month in cold weather, and mine was left for less than 24 hours in a garage. He didn't give much detail about it, but it seems that jump starting, which one would expect to work because the Owner's manual gives directions for it, did not work for him, either. The service manager couldn't explain why it didn't work for me and said he would consult a GM engineer and get back to me---a week ago. Chevrolet Customer Satisfaction said someone would call me back within two business days---five business days ago. Oh, well.

SeanNelson, I understand what you are saying about what should happen. However, I am uncertain about how confident I can be that what should happen will happen. What should happen is that a Bolt EV that had just been driven 10 miles at the end of which there were no in indications of problems, and that had 150 miles of range left when was it was turned off, should start without problems 20 hours later, but mine didn't. What should happen is that a Bolt EV with a dead 12V battery should work after being jump-started, but mine didn't. What should happen after a year-and-a-half-old car malfunctions so badly that it has to be towed to the dealer is that the problem is identified and corrected, but mine wasn't.

As it stands, even if I'm not at risk of loss of control at speed, I am at risk of having an inoperative car whenever I park it and leave it unplugged, which means that I risk significant inconvenience if I use the car in a way that even approximates normal use.

SeanNelson
Posts: 1444
Joined: Tue Jul 05, 2016 2:43 am
Location: Vancouver, BC

Re: Dead Car, Dead 12V Battery

Fri May 24, 2019 8:39 pm

bolter wrote:As it stands, even if I'm not at risk of loss of control at speed, I am at risk of having an inoperative car whenever I park it and leave it unplugged, which means that I risk significant inconvenience if I use the car in a way that even approximates normal use.

Sure, but for example if you can get the thing started then you can drive it to the dealer for service. There wouldn't be a need to tow it.

At some point, in your situation, I'd just go out and buy a d@mn 12V battery to see if it fixes the problem. If it does, then present the receipt to GM and demand reimbursement.

SparkE
Moderator
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Location: SF Bay Area

Re: Dead Car, Dead 12V Battery

Sat May 25, 2019 9:36 pm

Sean I disagree somewhat. I think *everybody* (ICE or EV) should have a Li_Ion "jump starter" in the trunk. In an electric, if you leave it connected you can just drive home and plug in (a 12V trickle charger) - but it allows you to drive home.

SeanNelson
Posts: 1444
Joined: Tue Jul 05, 2016 2:43 am
Location: Vancouver, BC

Re: Dead Car, Dead 12V Battery

Mon May 27, 2019 6:00 am

SparkE wrote:Sean I disagree somewhat. I think *everybody* (ICE or EV) should have a Li_Ion "jump starter" in the trunk. In an electric, if you leave it connected you can just drive home and plug in (a 12V trickle charger) - but it allows you to drive home.

Oh, I totally agree and I have one for my Bolt. I should point out that it needs to be regularly maintained - mine looses about 20% of it's charge over 3 months. It's not a "chuck it in the trunk and forget it" device, you should recharge it every few months.

bolter
Posts: 24
Joined: Sun Nov 26, 2017 8:51 pm

Re: Dead Car, Dead 12V Battery

Mon May 27, 2019 3:33 pm

I did have a power pack, and I did jump start the car, but it still was undriveable and had to be towed to the dealer.

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