Tidbit of engineering amazingnesss.
We have a Gen 1 Volt the company is leasing as a PR campaign.
It stays plugged in 98% of its life into a Lvl2 charger. If the car isn't driven in say 2+ month, the 12v battery goes flat, car can't be started/moved and must be trickle charged/battery replaced. The Lvl 2 charger only feeds the high voltage battery, GM didn't take into account a trickle charger for the standard 12V battery.
We've had to have the car towed 3-4 times in the past 4 years, ha!
Per the owner's manual.
"Four weeks to 12 months
. Discharge the high voltage
battery until two or three bars
remain on the battery range
indicator (Battery symbol) on the
instrument cluster.
. Do not plug in the high voltage
battery charge cord.
. Remove the black negative (−)
cable from the 12-volt battery
and attach a trickle charger to
the battery terminals or keep the
12-volt battery cables connected
and trickle charge from the
underhood remote positive (+)
and negative (−) terminals. See
Jump Starting on page 10-69 for
the location of these terminals.
{Caution
The vehicle is equipped with an
AGM/VRLA 12-volt battery, which
can be damaged by using the
incorrect type of trickle charger.
An AGM/VRLA-compatible
charger must be used, with the
appropriate setting selected.
Follow the trickle charger
manufacturer instructions".