Dead Car, Dead 12V Battery

[bolter]

Last night I parked my 18 month old 2017 Bolt EV with about 5400 miles in my garage. It showed 150 miles remaining range, and I didn't plug it in. This afternoon, I found that it wouldn't respond to the fob, wouldn't respond to door button presses, and when I plugged it in, the charge light didn't come on. Later, when I had time, I got in with the key. I checked the 12V battery voltage; it was 3.6. I hooked up a power pack to the 12V battery for a few minutes, and then the car worked normally. It's charging now.

I had driven the car daily, but I normally drive only a few miles per day. It had been three or four days since it was fully charged. I use hilltop reserve even though I'm not on top of a hill to prolong battery life because I have plenty of range anyway. The weather is mild now, and I think it's very unlikely the temperature in the garage wasn't between 60 and 70 F the whole time.

What happened? Why did the 12V battery go dead? Is the 12V battery supposed to be charged from the high-voltage battery when the car is in use? Does the 12V battery get charged when the car is plugged in? Are the factory 12 batteries good quality? If the 12V battery gets fully charged when the car is plugged in, it should have died in a few days, should it?

It seems bizarre to me that a car with a 60 kWH propulsion battery is designed so that it is disabled when an approximately 1 kWH accessory battery is discharged. I read some of the other posts about why having the separate 12V battery supposedly increases safety. Even if that is so, there should be a warning when its state of charge is getting low, and there should be something the driver can do from the driver's seat to make it recharge from the propulsion battery.

Although I sufferd about as little inconvenience as one could because I had anotner vehicle at hand to use, I had a modicrum of technical knowledge, I had a DVM, I had a power pack, and the failure occured in my garage, this just shouldn't happen.

[theothertom]

There's a saying...misery loves company. You're not alone in this. Other EV brands have the same issue. Of course this doesn't help solve the problem. 12V batteries go dead, even in ICE cars. In ICE cars you usually get slow cranking before it dies, which is somewhat of a warning. I agree there should be a monitor of some type in EV's so that we won't be left stranded.

[mrdrmorgan]

Last night I parked my 18 month old 2017 Bolt EV with about 5400 miles in my garage. It showed 150 miles remaining range, and I didn't plug it in. This afternoon, I found that it wouldn't respond to the fob, wouldn't respond to door button presses, and when I plugged it in, the charge light didn't come on. Later, when I had time, I got in with the key. I checked the 12V battery voltage; it was 3.6. I hooked up a power pack to the 12V battery for a few minutes, and then the car worked normally. It's charging now.

I had driven the car daily, but I normally drive only a few miles per day. It had been three or four days since it was fully charged. I use hilltop reserve even though I'm not on top of a hill to prolong battery life because I have plenty of range anyway. The weather is mild now, and I think it's very unlikely the temperature in the garage wasn't between 60 and 70 F the whole time.

What happened? Why did the 12V battery go dead? Is the 12V battery supposed to be charged from the high-voltage battery when the car is in use? Does the 12V battery get charged when the car is plugged in? Are the factory 12 batteries good quality? If the 12V battery gets fully charged when the car is plugged in, it should have died in a few days, should it?

It seems bizarre to me that a car with a 60 kWH propulsion battery is designed so that it is disabled when an approximately 1 kWH accessory battery is discharged. I read some of the other posts about why having the separate 12V battery supposedly increases safety. Even if that is so, there should be a warning when its state of charge is getting low, and there should be something the driver can do from the driver's seat to make it recharge from the propulsion battery.

Although I sufferd about as little inconvenience as one could because I had anotner vehicle at hand to use, I had a modicrum of technical knowledge, I had a DVM, I had a power pack, and the failure occured in my garage, this just shouldn't happen.

Your short trips might not be allowing enough time for the HV battery to charge the 12 volt battery. It might be a good idea to purchase a BatteryMinder 2012-AGM battery charger and at least once per month fully charge your 12 volt battery. AGM batteries are temperamental. BatteryMinder has an option that allows charging through the OBD-2 port inside the car. I use this on both of my Spark EVs and it works great!

[RichCapeCod]

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?

Rich

[bolter]

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?

Rich

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.

Any thoughts?

Does anyone know for sure how the charging system for the 12V battery is supposed to work?

[SparkEVPilot]

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?

Rich

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.

Any thoughts?

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).

[bolter]

Update:

They called back today and said they found nothing wrong with the car. I had a long, unproductive phone conversation with the service manager (When they called, the tech who worked on it was no longer available.). He said that they had checked the battery again twice today, and it was staying charged. No surprise there. In a nutshell, he said they found nothing wrong. Some of what he said was inconsistent with what the tech said yesterday. He couldn't explain why the 12V battery was discharged, as they said it was, after the car had been plugged in continuously for 60 hours. He also said that when the car is turned on, the 12V battery only charges when the car is moving, and that climate control runs off it. He also didn't seem to understand that to charge any battery, it is necessary to apply a voltage to it that is higher than the resting voltage. He also couldn't explain why the owner's manual gives directions for jump starting, but jump starting my car when the battery was dead still left it inoperable. In short, he didn't seem to understand how the car works, how batteries and chargers in general work, or what had happened with my car.

I'm going to pick it up in the morning. I'm taking a power pack with me, as well as a DVM. I'm hoping another customer asks me in front of employees why I brought a power pack when I came to pick my car up.

My biggest concern is safety. Can anyone tell me what happens if I'm driving at 70 mph in traffic and the 12V battery dies? Do I lose steering? Do I lose brakes? Do the brakes lock up? Any information about this will be very much appreciated.

I have ordered a service manual. I think that, with access to detailed information about intended behavior, I can diagnose it. In addition, I'll have an authoritative source of information about what should happen, instead of something I read on the Internet, to confront the service people with. It's too bad I have to approach it this way, but, if it's what it takes, I can do it.

Can anyone recommend a good combination of Bluetooth OBD device and iOs app?

[bolter]

I picked the car up today. Before I moved it I checked the 12V battery voltage; it was 12.5. 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? Would steering work? Would it set the parking brake and put itself into park, as it normally does when turned off? I told him I wanted a manager to call me to answer those questions. He said he would give the message to the Service Manager. After three hours, when no one had called, I called him, and he said he gave him the message right after I left. I then called the GM Customer Care number and talked to someone who was obviously just a call-taker. She said a more senior person would call me within two business days.

I said from the first that I was lucky that it happened when the car was in my garage. I might not be so lucky next time. Even if the car didn't become uncontrollable, I would either be stopped in a traffic lane without working emergency flashers, or would coast to the shoulder without working turn signals. Neither seems very safe, and that's the best case.

I loved my Bolt EV until five days ago. Now, I'm not so sure.

Any advice, especially about diagnosing it myself or getting better support than I've had so far, will be appreciated.

In my state, I only have to give the dealer one shot at fixing a problem that could cause death or serious injury before starting a lemon law proceeding, and I'm thinking about doing that. I'll wait until I hear from the GM rep to decide

[bolter]

Further update:

The service manager did finally call me after about five hours. He tried to reassure me that the car wouldn't shut down while in motion. However, he was much less dogmatic and much more willing to say so when he didn't know something instead of making assumtions. He promised to contact a GM engineer regarding my questions about the car's expected behavior when the 12V battery goes dead while driving and my question about why it was still undrivable after jump starting. The manual gives directions for jump starting, and there's no reason to do it if it won't make the car functional.

[DanDietrich]

On my Nissan Leaf the 12 volt battery does not charge when the car is plugged in. Leaving the car plugged in for 60 hours would lead my Leaf to be dead, just as your car was, especially if there was any draw, like a bluetooth OBD2 transmitter. I had thought that the Bolt was programmed differently, but perhaps not. I started keeping a small 12 volt jumping battery around, the kind that is a usb battery charger as well, and if the car died i would hook it to the battery for 5 minutes and then it would start right up. A recent new battery and series of software updates, as well as care about not leaving it plugged in seems to have solved my issue.