[Boltsport]

This is a relevant question for me as a new Bolt owner, and one who doesn't drive much. The car will sit in my garage for 2-3 days, sometimes.
With my two Priuses the last 11 years, I had to replace the 12v battery after about 4 years.

When does the 12V battery get charged? While you are driving (like a conventional car)? While you are charging the big battery?

 

[Sean Nelson]

Yes, the 12V battery does get charged from the high voltage battery. See this thread: https://www.chevybolt.org/threads/12v-battery-charging.10290/

 

[redpoint5]

It gets charged anytime the car is "On" (is that ready in Bolt-speak?). Also when the traction (big) battery is charging. Finally, the Bolt checks the charge level periodically when parked and uses the traction battery to charge if it's below some threshold. It does this more often when plugged in, so keep your car plugged in when not in use.

The Prius batteries should have lasted longer than 4 years. Are the keyfobs stored close to the vehicles? This causes the vehicle to not enter the full sleep state.

 

[Boltsport]

It gets charged anytime the car is "On" (is that ready in Bolt-speak?). Also when the traction (big) battery is charging. Finally, the Bolt checks the charge level periodically when parked and uses the traction battery to charge if it's below some threshold. It does this more often when plugged in, so keep your car plugged in when not in use.

The Prius batteries should have lasted longer than 4 years. Are the keyfobs stored close to the vehicles? This causes the vehicle to not enter the full sleep state.

Thanks. The key fobs are in the house. The car is in the garage, maybe 25 ft away.

Looks like the Bolt 12V battery is automatically recharged by the big Bolt battery. And the info system will alert you to any problem with the 12v battery.,

 

[psyflyjohn]

You can buy an inexpensive voltmeter that plugs into the 12V system via the "lighter socket". It will show the charging system in action as you drive.

 

[surgeonFWW]

Many of us (including me) bought an inexpensive battery trickle charger and hook up the 12V overnight once every 2-3 months (for me, monthly on the last day of the month) to keep it in good shape. The argument was that since it did not need to produce "cold-cranking amps" upon startup (but only bring the traction battery online) "dendrites" would build up on the plates of the 12V, eventually shorting it out, and that the trickle charge removes these. I am happy, though it may be overkill, but I am only at 27 months.

 

[psyflyjohn]

Yep, I put our Bolts on a small charger, overnight, once a month to desulphate those pesky dendtrites and extend the life of the AGM batteries. If you do try this, be sure you have a charger that specifically works with AGM batteries, as the voltages are slightly different than regular lead acid batteries.

 

[TotaledJetta]

You can buy an inexpensive voltmeter that plugs into the 12V system via the "lighter socket". It will show the charging system in action as you drive.

Definitely. That help me understand what was going on, when I had 12 v trouble.