[Bruce Allen]

5 yrs of ownership. 89k miles. Replaced original 12v agm battery this past June-2022.

No issues ever with 12v systems.

Drove for a few errands around town. Returned home and parked. Moved the car about 10 minutes later to position it out of the way (about 20 ft) to drive my ice vehicle.

Returned home 3 hours later in ice vehicle. Went to move my bolt back into its normal spot. The drivers door unlocked and got in. Stuff was fading, lights flickered, weird very weak horn beeps. Nothing would boot up. Other doors wouldn't unlock and the half way turned on car wouldnt shut off. I opened the hood disconnected the 12v so car would shutoff. Reattached wire about 60 seconds later. Same issues. Assumed dead 12v so I jumped it with ice vehicle.

Now it's next day and all seems back to normal. After 2 hours of bolt being on and driving I took it to advance auto parts for a 12v battery check. Test good. Drove 15 minutes away to another advance auto parts for 2nd opinion and 12v test. It tests good again.

Long story but has anybody else have 12v gremlins before??!!

The cars computer went bonkers and was reporting on the dash vehicle theft warning and the advance auto parts woman at 2nd store also checked the errors from check engine light. It had 8 reported problems.

Now after about 5 or 6 restarts and driving, all the check engine warnings are gone.

? ? Weird

 

[SpicyBolt]

5 yrs of ownership. 89k miles. Replaced original 12v agm battery this past June-2022.

No issues ever with 12v systems.

Drove for a few errands around town. Returned home and parked. Moved the car about 10 minutes later to position it out of the way (about 20 ft) to drive my ice vehicle.

Returned home 3 hours later in ice vehicle. Went to move my bolt back into its normal spot. The drivers door unlocked and got in. Stuff was fading, lights flickered, weird very weak horn beeps. Nothing would boot up. Other doors wouldn't unlock and the half way turned on car wouldnt shut off. I opened the hood disconnected the 12v so car would shutoff. Reattached wire about 60 seconds later. Same issues. Assumed dead 12v so I jumped it with ice vehicle.

Now it's next day and all seems back to normal. After 2 hours of bolt being on and driving I took it to advance auto parts for a 12v battery check. Test good. Drove 15 minutes away to another advance auto parts for 2nd opinion and 12v test. It tests good again.

Long story but has anybody else have 12v gremlins before??!!

The cars computer went bonkers and was reporting on the dash vehicle theft warning and the advance auto parts woman at 2nd store also checked the errors from check engine light. It had 8 reported problems.

Now after about 5 or 6 restarts and driving, all the check engine warnings are gone.

? ? Weird

We had 12 volt battery gremlins on our new 2023 EUV, just two weeks ago.

The car wouldn't shut off, or shift out of Park. We got the "conditions not right to shift" warning. I was out of town at the time, but my wife disconnected the battery waited and tried again, same thing. The 2nd time she left it to shut itself off and came back later to see the wipers going back and forth real slowly. Car was in the garage, dry as a bone. She disconnected the battery again and called the dealer.

Anyway, it was towed to the dealership and they replaced the 12 volt battery and now it's fine. They noted it threw a ton of codes, but nothing else was wrong.

 

[MichBolt]

5 yrs of ownership. 89k miles. Replaced original 12v agm battery this past June-2022.

No issues ever with 12v systems.

Drove for a few errands around town. Returned home and parked. Moved the car about 10 minutes later to position it out of the way (about 20 ft) to drive my ice vehicle.

Returned home 3 hours later in ice vehicle. Went to move my bolt back into its normal spot. The drivers door unlocked and got in. Stuff was fading, lights flickered, weird very weak horn beeps. Nothing would boot up. Other doors wouldn't unlock and the half way turned on car wouldnt shut off. I opened the hood disconnected the 12v so car would shutoff. Reattached wire about 60 seconds later. Same issues. Assumed dead 12v so I jumped it with ice vehicle.

Now it's next day and all seems back to normal. After 2 hours of bolt being on and driving I took it to advance auto parts for a 12v battery check. Test good. Drove 15 minutes away to another advance auto parts for 2nd opinion and 12v test. It tests good again.

Long story but has anybody else have 12v gremlins before??!!

The cars computer went bonkers and was reporting on the dash vehicle theft warning and the advance auto parts woman at 2nd store also checked the errors from check engine light. It had 8 reported problems.

Now after about 5 or 6 restarts and driving, all the check engine warnings are gone.

? ? Weird

Symptoms certainly suggest 12V battery issue. Did Advance Auto Parts test the battery under load? Also, in the testing process, did you jostle or tighten the connections to the battery terminals?

I suppose another possibility is a loose connection in a wiring harness somewhere. Do you park in an area with small critters (mice, rats, chipmunks, etc.)?

 

[Bruce Allen]

No critters ever seen here. The terminals were tight. I think I'm just going to chalk it up as electric gremlins and hope it doesn't do this again under harsh Chicagoland weather. It's currently no so bad for November. 😊

 

[GJETSON]

No critters ever seen here. The terminals were tight. I think I'm just going to chalk it up as electric gremlins and hope it doesn't do this again under harsh Chicagoland weather. It's currently no so bad for November. 😊

Wow! Timely. Our 2017 Bolt battery was built in August of 2016, in Korea. It went in the Bolt in December of 2016. It sat somewhere until we bought it in June of 2017. It has had a pretty easy life since then. Always plugged in, in our temperate garage, in temperate central Virginia. It seems to be fine. When I sneak up on it with a VOM, it is always over 12 volts. Googling around about the life expectancy of an AGM battery suggests 6+ years is approaching the end. If we were still a two car household, I would just wait until it messed up, and one of us would show up with jumper cables. I can get a NAPA replacement in 24 hours, delivered to the store near here. But as our only vehicle, I am considering being proactive.

https://www.napaonline.com/en/p/BAT9847?cid=paidsearch_shopping_dcoe_google&store=21220

What brand did you buy? New or rebuilt?

Do they disconnect the battery for the load test?

 

[SpicyBolt]

Wow! Timely. Our 2017 Bolt battery was built in August of 2016, in Korea. It went in the Bolt in December of 2016. It sat somewhere until we bought it in June of 2017. It has had a pretty easy life since then. Always plugged in, in our temperate garage, in temperate central Virginia. It seems to be fine. When I sneak up on it with a VOM, it is always over 12 volts. Googling around about the life expectancy of an AGM battery suggests 6+ years is approaching the end. If we were still a two car household, I would just wait until it messed up, and one of us would show up with jumper cables. I can get a NAPA replacement in 24 hours, delivered to the store near here. But as our only vehicle, I am considering being proactive.

https://www.napaonline.com/en/p/BAT9847?cid=paidsearch_shopping_dcoe_google&store=21220

What brand did you buy? New or rebuilt?

Do they disconnect the battery for the load test?

You can get an ACDelco LN1 for less at Summit Racing. I've purchased from them before although not a battery.

 

[jefro]

Charge then load test battery.

 

[GJETSON]

Charge then load test battery.

If I drive to town, the onboard charger should have it fully charged, right?

 

[sir3lit]

If I drive to town, the onboard charger should have it fully charged, right?

The EV isn't like a car where it needs the engine to spin the alternator. The car should have it being maintained 24/7...

 

[MichBolt]

A cheap-ish insurance policy that might be useful anyway is a portable battery jump starter. I got one from Costco similar to this one:

https://www.costco.com/type-s-8000mah-portable-power-bank-jump-starter-with-lcd-screen.product.100813421.html

In theory, once the system is powered on, the main traction battery will maintain the 14V bus. So even if the 12V battery is dying, you just need to get the Bolt started.

 

[Bruce Allen]

I didn't want to be stranded somewhere so I replaced it at 5 yrs. Summit racing delivered it. Easy remove and install new one. They did not disconnect to test the battery. Its still holding a charge just fine now.

Weird that's it

 

[sir3lit]

They did not disconnect to test the battery.

If that's the case, the DC-DC converter could've been supplying its 165A max to the tester... giving it a false positive that it's good... just a thought

 

[Sean Nelson]

I can get a NAPA replacement in 24 hours, delivered to the store near here. But as our only vehicle, I am considering being proactive.

Maybe buy the spare battery and leave it on the shelf (or in the trunk) until you need it?

Do they disconnect the battery for the load test?

I do my load testing with the battery connected - but I leave the hood open overnight and make sure I don't have my key fob on me when I do my load test so as to not wake the car up.

 

[sir3lit]

Battery Sulfation Mode
Battery sulfation mode is used to help maintain the battery life. The charging system will enter a battery sulfation mode which tries to increase the vehicle charging when the charging system voltage is less than 13.2 V for about 30 minutes. Once in this mode, the BCM will set a targeted output voltage between 13.9–15.5 V for about 5 minutes. Following this 5 minutes, the BCM will then determine which mode to enter depending on the system voltage requirements.

Normal Mode
The BCM will enter Normal Mode whenever one of the following conditions are met.

• The wipers are ON for more than 3 seconds.
• GMLAN Climate Control Voltage Boost Mode Request is true, as sensed by the HVAC control head. High speed cooling fan, rear defogger and HVAC high speed blower operation can cause the BCM to enter the Charge Mode.
• The estimated battery temperature is less than 0°C (32°F).
• Vehicle Speed is greater than 145 km/h (90 mph)
• Current Sensor Fault Exists
• System Voltage was determined to be below 12.56 V
• Tow/Haul Mode is enabled

When any one of these conditions is met, the system will set targeted generator output voltage to a charging voltage between 13.9–15.5 V, depending on the battery state of charge and estimated battery temperature.

Fuel Economy Mode
The BCM will enter Fuel Economy Mode when the ambient air temperature is at least 0°C (32°F) but less than or equal to 80°C (176°F), the calculated battery current is greater than −8 A but less than 5 A, and the battery state of charge is greater than or equal to 85 percent. Its targeted 14V Power Module set-point voltage is the open circuit voltage of the battery and can be between 12.6–13.2 V. The BCM will exit this mode and enter Normal Mode when any of the conditions described above are present.

Headlamp Mode
The BCM will enter Headlamp Mode whenever the high or low beam headlamps are ON. Voltage will be regulated between 13.9–14.5 V.

Voltage Reduction Mode
The BCM will enter Voltage Reduction Mode when the calculated battery temperature is above 0°C (32°F) and the calculated battery current is greater than −7 A but less than 1 A. Its targeted 14V Power Module set-point voltage is 12.9–13.2 V. The BCM will exit this mode once the criteria are met for Normal Mode.

Battery Maintenance Mode
That battery maintenance mode is designed to ensure the 12V battery has a good state of charge. It accomplishes this by checking the voltage of the 12V battery and providing a charge if needed.

When the vehicle cord is plugged in

• The Hybrid/EV Powertrain control module (HPCM2) will check the 12V battery every 6 hours if the ignition is off. If the voltage is below a temperature dependent threshold ranging from 12.1 (cold) to 12.4 (warm)V, the Hybrid/EV Powertrain control module (HPCM2) will send the voltage set point to the engine control module (ECM). The engine control module (ECM) will send this to the 14V Power Module. Battery maintenance mode will charge the battery for 2-3 hours. If the Ignition is ON, the APM will cycle on as needed to maintain the 12V SOC.

When the vehicle cord is not plugged in

• The Hybrid/EV Powertrain control module (HPCM2) will check the 12V battery every 4 days (2.5 to 3 days) and if the voltage is below a threshold of 12.0 may activate battery maintenance. If the high voltage battery state of charge is greater than 40% and the propulsion system is not active, Hybrid/EV Powertrain control module (HPCM2) will send the voltage set point to the engine control module (ECM). The engine control module (ECM) will send this to the 14V Power Module. Battery maintenance mode will charge the battery for 45-90 minutes..

Plant Assembly Mode
The BCM will increase charging voltage for the first 500 miles of operation in an effort to ensure that the 12 V battery is fully charged when the vehicle is delivered to the customer.

Here are some of the "modes" the car will be in... I find it interesting.

 

[Bruce Allen]

Makes sense the 12v battery was warm to the touch the 1st hour of car being on. By the 2nd hour it had cooled off.

 

[GJETSON]

Maybe buy the spare battery and leave it on the shelf (or in the trunk) until you need it?


I do my load testing with the battery connected - but I leave the hood open overnight and make sure I don't have my key fob on me when I do my load test so as to not wake the car up.

If I actually buy one. It is going in the car. My wife isn't going to swap out a dead battery on the side of the road. and I am not going to ride my bicycle there to do it. I could, but I don't need the penance.

That would work, but if the OP drove there, they would need to open the hood, and the car would likely not be dormant. It would need to sit with the hood open, and everything else off, and undisturbed for at least ten minutes for a total shutdown.

 

[accelerus]

A cheap-ish insurance policy that might be useful anyway is a portable battery jump starter. I got one from Costco similar to this one:

https://www.costco.com/type-s-8000mah-portable-power-bank-jump-starter-with-lcd-screen.product.100813421.html

In theory, once the system is powered on, the main traction battery will maintain the 14V bus. So even if the 12V battery is dying, you just need to get the Bolt started.

With the way GM designs 12V/HV circuits -- unfortunately it's not as easy. There was a situation on my Volt where 12V battery wasn't being maintained, and HV system would not kick over any juice to the 12V system. Result was car ran fine, until it didn't, for me it was total loss of all power on the side of the road and towed to dealership.

(now) I keep a 12V jump/booster pack in my emergency kit in the underfloor storage for this reason. Worst case, either battery itself shits itself, or the car decides it can't/won't charge it anymore, I still have enough 12V juice in the pack to get me home since all it has to do is run computers/contactors.

 

[Eriamjh1138]

$149 is a good price. I just pad $200 from Amazon, shipped. Battery was made in March of 2022, but mine lasted 6 years from manufacture and wasn't dead. I just changed it before a big trip since I could not be certain I would not have trouble.

 

[EV Engineering]

The question that worries me, does Bolt need adaptation when new 12V battery is replaced.



If someone is familiar with this please respond to my question.

 

[LarryO]

5 yrs of ownership. 89k miles. Replaced original 12v agm battery this past June-2022.

No issues ever with 12v systems.

Drove for a few errands around town. Returned home and parked. Moved the car about 10 minutes later to position it out of the way (about 20 ft) to drive my ice vehicle.

Returned home 3 hours later in ice vehicle. Went to move my bolt back into its normal spot. The drivers door unlocked and got in. Stuff was fading, lights flickered, weird very weak horn beeps. Nothing would boot up. Other doors wouldn't unlock and the half way turned on car wouldnt shut off. I opened the hood disconnected the 12v so car would shutoff. Reattached wire about 60 seconds later. Same issues. Assumed dead 12v so I jumped it with ice vehicle.

Now it's next day and all seems back to normal. After 2 hours of bolt being on and driving I took it to advance auto parts for a 12v battery check. Test good. Drove 15 minutes away to another advance auto parts for 2nd opinion and 12v test. It tests good again.

Long story but has anybody else have 12v gremlins before??!!

The cars computer went bonkers and was reporting on the dash vehicle theft warning and the advance auto parts woman at 2nd store also checked the errors from check engine light. It had 8 reported problems.

Now after about 5 or 6 restarts and driving, all the check engine warnings are gone.

? ? Weird

I had the same thing happen several months ago on my 2019. I charged the battery and it's been fine since. I think a gremlin may have messed up the charging or possibly left the headlights on. I started carrying a boost battery along with my 10mm reset tool. LOL