Do Energizer_® NiMH Rechargeable batteries have to be fully drained before recharging? Do they have a “memory”?

No. Energizer_® NiMH Rechargeable batteries do not have the memory problems typically associated with older Nickel Cadmium rechargeable battery technology. NiMH Rechargeable batteries can be recharged after a few hours of use or whenever convenient. If batteries have been stored for more than 1 month, be sure to recharge before using to maximize power.