I don't know the exact answer but when I worked there while in college 20 years ago the package cars were never connected to chargers overnight, nor did they re

I don't know the exact answer but when I worked there while in college 20 years ago the package cars were never connected to chargers overnight, nor did they receive any other special attention. I would imagine that they use heavy duty batteries and just spend an enough time driving and idling that it all balances out during the workday.