From page 259 of owner's manual of Bolt EV: https://my.chevrolet.com/content/da...als/2017/Chevrolet/BOLT EV/Owner's Manual.pdf
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 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 - North America 0 295 for the location of these terminals.