Depends on the chemistry. Assuming you're describing recent lithium batteries, it's good to discharge as shallow as possible, and charge as full as possible (a

Depends on the chemistry. Assuming you're describing recent lithium batteries, it's good to discharge as shallow as possible, and charge as full as possible (according to Peukert curve) to preserve lifespan. Most modern laptops apply the proper charge impedance as part of their charging circuits. Older laptops that used Ni-Cd would benefit from a full ('til it's dead) discharge before a recharge.