little 12v battery under hood

[bobo]

I am a new owner. Completely new the the EV world!
What is that little 12 volt battery under the hood for? Thanks

 

[user 4721]

It powers the computer systems and the infotainment devices. If the little 12V ever goes dead, you will not be able to start your Bolt !

Whilst plugged-in, the Bolt will top-up the 12V battery when necessary. When not plugged-in, the Bolt will top-up the 12V once in a while, provided the big battery is mostly charged.

A brand-new Bolt may have a damaged OEM 12V battery because it's been sitting in the dealer's lot for months without topping-up. Sometimes it will develop a bad cell, and you have less than 12V to power the computer. The console display will warn you about this.

Be nice to your little 12V !!

 

[SeanNelson]

It powers the computer systems and the infotainment devices....

...while the car is turned off. When the car is turned on that power comes from the main 60 kWh battery. But the computers still need to run when the car is turned off to provide things like Internet connectivity (i.e., remote fob commands via cell phone app), recognize key fobs to unlock the car, etc. etc.

 

[bobo]

Thank you.
Maybe to be on the safe side I should replace this battery every so often?
I think the ave battery lasts about 5 years.
So... say every 2 1/2 years? Would be cheap insurance?
What do you think?

 

[theothertom]

Most everything in the car works off the 12V battery....lights, heat, radio, wipers, A/C, computer, etc. Of course the drive motor works off the main battery. There's a lot of discussion about how to check the 12V battery, but it seems that it doesn't give warning when it dies. And when it dies, your car won't start. So replacing it early is a good idea.
Edit: Check out this thread on the 12V battery
http://www.mychevybolt.com/forum/viewtopic.php?f=10&t=8505

 

[bobo]

Thanks for link. Good read. :ugeek:

 

[WetEV]

Most everything in the car works off the 12V battery....lights, heat, radio, wipers, A/C, computer, etc. Of course the drive motor works off the main battery. There's a lot of discussion about how to check the 12V battery, but it seems that it doesn't give warning when it dies. And when it dies, your car won't start. So replacing it early is a good idea.
Edit: Check out this thread on the 12V battery
http://www.mychevybolt.com/forum/viewtopic.php?f=10&t=8505

Heater works on the drive battery. Has to, due to 5 kW / 12 V is far too many Amps (416 A!).

 

[SeanNelson]

Most everything in the car works off the 12V battery....lights, heat, radio, wipers, A/C, computer, etc.

To be clear, 12V power comes from the high voltage battery via an inverter when the car is turned on. The 12V battery is only there to provide the power needed for baseline functions when the car is turned off.

 

[bobo]

Thanks. That does clear it up for me.
So, my Bolt has a 12V inverter.
Do you have any idea what the input voltage is from the "drive" batteries?

 

[SparkEVPilot]

Thanks. That does clear it up for me.
So, my Bolt has a 12V inverter.
Do you have any idea what the input voltage is from the "drive" batteries?

The HV battery is about 400 volts DC.

One suggestion I found for keeping your 12 volt battery healthy is this - once a month fully charge your 12 volt battery over night. The 12 volt battery used in the Bolt and Spark EV is an AGM battery and requires a special charger. I am using a BatteryMINDer model 2012 AGM. This charger has an option that allows you to charge through the OBD2 port below the dash by the hood release. I also purchased a couple of extension cables that allow me to mount the charger on a wall by a 120 VAC outlet. This way I just have to pull the cable to the car, drop the window a bit and plug into the OBD2 connector. I has been working great.

 

[SeanNelson]

One suggestion I found for keeping your 12 volt battery healthy is this - once a month fully charge your 12 volt battery over night.

I'm pretty skeptical that this would be necessary if your battery is in good condition and you drive your Bolt a reasonable distance on a regular basis. I've never done anything special with my battery in almost 2 years and I've never had any issues.

If you leave your Bolt sitting idle for extended periods of time or if you only drive a few km a week then I can see that this might be beneficial. And it might help if your 12V battery capacity was damaged because it got almost fully discharged for one reason or another - but in that case I'd suggest that the better remedy would be to replace it with a new battery.

 

[SparkEVPilot]

One suggestion I found for keeping your 12 volt battery healthy is this - once a month fully charge your 12 volt battery over night.

I'm pretty skeptical that this would be necessary if your battery is in good condition and you drive your Bolt a reasonable distance on a regular basis. I've never done anything special with my battery in almost 2 years and I've never had any issues.

If you leave your Bolt sitting idle for extended periods of time or if you only drive a few km a week then I can see that this might be beneficial. And it might help if your 12V battery capacity was damaged because it got almost fully discharged for one reason or another - but in that case I'd suggest that the better remedy would be to replace it with a new battery.

Granted, it is a personal preference. But, it will not hurt anything and may prolong the life of the battery by periodically desulfating it.