The AC power adapter is needed to maintain the charge on the internal NiMH battery.

Instead of using the battery the A33 can also be powered from the AC adapter when portability is not required.  This way the unit should have a full charge and can be disconnected at any time for portable operation.

Battery life should not be affected by leaving the AC adapter connected for extended periods of time.

To maintain the battery charge when not in use, the A33 can be disconnected from power and the ON/OFF switch on the right end of the unit set to OFF.  This should reduce any long term charge decrease on the battery.

If the A33 battery has run down, it is suggested that a recharge take place.  Leaving the battery in an exhausted state for an extended period may shorten its life.