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Discussion Starter · #1 ·
What's the deal with the 12V battery, when the car is off, but the hazard lights or the dome lights are on for a little while?

I used hazards for 30 minutes while unloading luggage and running it upstairs. Then the car would not start due to charging system error. Turned everything off and let the car just sit for 15 minutes, then it started.

Car wash guys kept doors open and dome lights on whilst vacuuming interior. Couldn't have been more than 20 minutes. Upon starting, car gave a cannot charge warning, then started anyway.

What the **** is going on, is this all normal? Such a lite 12V capacity? Do I need to carry a jumper cable?
 

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May be a sign of impending failure of the 12 volt battery. Worse case, the DC-DC charger is not functioning as it should. But I'd blame the battery first. Still check the obvious though. Corrosion on terminals or they're loose.

Some forum members carry an emergency jump start battery for just this scenario. Jumper cables would work fine and the manual addresses its use.
 

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30 min is way past the batteries rated reserve.
If you need to do that often, get a micro jump pack. I recommend it to everyone.

Follow this link!

[ame]https://www.amazon.com/Antigravity-Batteries-XP-3-Portable-Flashlight/dp/B075YC2NYG/ref=sr_1_13?ie=UTF8&qid=1531961050&sr=8-13&keywords=micro+jump+pack[/ame]
 

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The Bolt's 12v battery part number must be classified information. I'm not able to find the OEM part number even though part diagrams show it labeled as #1 , the part descriptions omit #1 and go on to #2 .

That said, I found this replacement battery which should be equivalent, and it's rated for 50 Ah, which is not a small capacity at all. It should easily run dome lights for 20 minutes, or hazards for 30 and still start the car.

If there is an accessory mode that turns on things like the radio and interior fans, but does not put the car into "ready" mode, it can quickly drain a battery. Fans can pull a couple hundred watts.

https://www.carid.com/acdelco/professional-battery-mpn-ln1agm.html?singleid=743277260&url=96670651

Dealerships are notorious for killing 12v batteries by leaving car doors open too long, or people checking out the features of the car while in accessory mode rather than "ready". You'll see them running around a huge battery cart on wheels just for the purpose of jumping cars with dead batteries.

I'd have the dealer replace it under warranty, especially given the probability that they caused it to be weak in the first place.
 

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I've seen a few posts of people with 12V battery issues, and I generally assume that they've occurred with cars that had compromised 12V batteries as a result of having sat on the lot unused for several months.
Based on what I've read here, it seems merely sitting for months on a lot shouldn't kill the 12v battery. Even unplugged the car checks the voltage something like once every 6 hours and charges it if needed. I'd say something like leaving a door ajar killed the battery.
 

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so NOW i have a valid reason for having swapped out the interior lighting for LEDs!

prescient I am! :)
I also swapped all the interior and exterior lamps for LED, even the headlamps, on my 2009 Chevy Equinox. But even if the lights were left on, it will shut down the lights after one minute all by itself. That is the job of the BCM (Body Control Module), so it will never allow any light to run down the 12 VDC battery.
 

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The 12 volt battery is very small. You could leave the car in run mode when extended battery
use is required.
If running the flashers for extended periods is a regular routine for the OP, I would suggest-


  1. The above procedure. Leave the car in run mode. That's the beauty of the BEV, no idling motor with tail pipe emmisions. The amount of power consumed from the high voltage battery would not even be noticeable.
  2. change the turn signal bulbs out for LEDs. This should extend your run time on the 12v battery.
  3. Get the specs on the Bolt's 12v battery and see if you can find a battery that will fit with higher capacity.
 

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I can't see why the lights stayed on unless they were closing and opening the doors reactivating the system.


The system is designed to shut off the power if you leave lights on or a door open.


I have left the dome light on, next day when I came out to start the car after standing all night the dome light came back on when the car started.


I would say there is something wrong with your 12V battery, those things do go bad, some are junk from the get go.


Take the car to any auto part store that knows how to test a battery have them do a LOAD test this will determine if you battery is junk.


Then after they tell you its no good take it back to the dealer to get it replaced, get some paperwork from the tester if you can to help you get a new battery.


((You might want to try slow charging the battery I put a float charger on my car every once and awhile sometimes it charges for hours before it brings the battery up to fully charged.))
 

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I've seen a few posts of people with 12V battery issues, and I generally assume that they've occurred with cars that had compromised 12V batteries as a result of having sat on the lot unused for several months.
Based on what I've read here, it seems merely sitting for months on a lot shouldn't kill the 12v battery. Even unplugged the car checks the voltage something like once every 6 hours and charges it if needed. I'd say something like leaving a door ajar killed the battery.
My reading of the 12V battery maintenance algorithm is that this only happens when the high voltage battery is at a 40% or greater state of charge, which may not be the case if the car has been sitting unused on the lot for a long time. Bolts are not shipped from the factory with their batteries fully charged.

This would explain why the 12V batteries in some Bolts won't hold a charge. It's one thing for the battery to run down due to some accessory being on, but failure to keep a proper charge suggests that the battery suffered some serious indignity at some point.
 

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30 min is way past the batteries rated reserve.
If you need to do that often, get a micro jump pack. I recommend it to everyone.

Follow this link!

https://www.amazon.com/Antigravity-...d=1531961050&sr=8-13&keywords=micro+jump+pack
IMO any car battery should be able to run the hazard lights for several hours and still have enough juice to start. Especially in a car like the Bolt where the 12V battery is only needed to power the electronics and activate the DC-DC converter.

It seems that the Bolt is far too sensitive to low voltage conditions with the 12V battery.
 

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Based on what I've read here, it seems merely sitting for months on a lot shouldn't kill the 12v battery. Even unplugged the car checks the voltage something like once every 6 hours and charges it if needed. I'd say something like leaving a door ajar killed the battery.
No, that's not true. WHEN PLUGGED IN (and not charging) it will wake up and check the status of the 12V battery every 6 hours. If the 12V battery is low the car will begin charging it for up to 2 to 3 hours.

If the car is not plugged but has been turned on within the last 30 days, it will wake up every 3 days to check the 12V battery and if the main battery is at least 40 percent full it will begin charging the 12V battery for 45 to 90 minutes.
 

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If running the flashers for extended periods is a regular routine for the OP, I would suggest-


  1. The above procedure. Leave the car in run mode. That's the beauty of the BEV, no idling motor with tail pipe emmisions. The amount of power consumed from the high voltage battery would not even be noticeable.
  2. change the turn signal bulbs out for LEDs. This should extend your run time on the 12v battery.
  3. Get the specs on the Bolt's 12v battery and see if you can find a battery that will fit with higher capacity.

Last time I changed the aux battery in my 2011 Volt, I took the old one to an auto parts store, and had him find one the same size that was a VRLA AGM with the highest capacity available. We don't give a rat's patootie about CCA, because the draw isn't extreme (like with a starter). When It's time to replace the aux in the Bolt, I'll probably use a VMAX Tanks that fits. They're awesome batteries.
 

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I purchased a 12V indicator that plugs into the cigarrette lighter/12V port to monitor the status of the 12V system. It turns off when the Infotainment system is off as it appears to be on the same accessory-type circuit (but not ignition in the old-school sense of the word).

It was like $3, eBay, blah blah blah. Like this one (an expensive example), so you know what I mean.

I've opened doors and the hatch for vacuuming, cleaning, etc. and left them open and have had no 12V issues. My car is usually well above 40% SOC. The dome light shuts itself off if doors are left open after 10-15m, so that safety is built in. As for hazards, they should be able to run for 24Hrs or more without running the 12V battery down, but as people have mentioned, maybe you have a battery or APM issue.

If you use a voltage indicator, at least you will be able to tell if the 12V system is dropping below 9V, the level at which everything is supposed to still work to be able to start the car. If it is only at 10-11V and giving you that error. Just wait a few minutes and try again.

Sometimes, a glitch catches a voltage drop and an error occurs. Waiting allows the voltage to rebound from a drain and it may be enough to get you on your way.
 

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The battery rundown system can not over ride the hazard lamps. The battery has a low CCA
output with a low reserve due to an EV's or PHEV's starting system. This works against us
as far as 12 volt battery reserves. Like I tell everyone. Keep a micro jump pack in the car!
 

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Discussion Starter · #19 ·
OP Follow-up

If the car is not plugged but has been turned on within the last 30 days, it will wake up every 3 days to check the 12V battery and if the main battery is at least 40 percent full it will begin charging the 12V battery for 45 to 90 minutes.
I went on vacation for three weeks and first prepared my Bolt by charging it 100%. I did not leave it plugged in that entire time because, as a fire/lightning precaution, I disabled power into my garage. I reasoned that the every 3 day check would keep the 12V charged.

During vacation I was able to remotely check the main battery SoC, using my.chevrolet.com, and there wasn't any change.

Upon returning, the Bolt was dead as a door knob. Upon opening the doors, no lights or indications at all. So I closed the garage breaker, then attached a 12V, 10A charger directly to the 12V (grounding to chassis). The battery sucked a full 10A for a minute or so, then gradually settled down. It reached 0A after a few hours. After that, all Bolt systems were back to normal, and there have been no follow-on issues.

I could not reach a conclusion about the initial 12V SoC: whether it was initially low, or the charging system is deficient, or there's a drain in the circuitry.

I observe that my Prius absolutely MUST have a 12V trickle charge if the car is not driven for more than 3 days; it will go dead, too. However I have concluded in that case that the Prius computer system creates a constant 12V drain.

It has not been mentioned in this forum that the Bolt computer also presents a constant drain--could it?
 

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It's a good idea to fully charge the 12V battery before leaving on vacation if you aren't going to leave the vehicle plugged in.
 
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