HP iPAQ hw6510 User Manual page 164

CAUTION: Do not allow the battery installed in your HP iPAQ to
discharge completely. Doing so will not harm your HP iPAQ or battery,
but your device will lose all data not stored in File Store (ROM).
Discharging the battery completely is similar to performing a hard reset.
Refer to Chapter 1, in the section "Performing a Hard Reset." for more
information on performing a hard reset.
Managing the Battery 13–10