Palm Handhelds m500 - Manual (Page 21)

Chapter 1 Page 11
4. Plug the AC adapter into any AC current outlet.
Charging your handheld
Your handheld contains a Lithium-ion polymer battery that is
recharged each time you place the handheld in the cradle. Just place
your handheld in the cradle for two hours for an initial charge before
you use it. Then place it in the cradle for a few minutes each day to
recharge the battery to full capacity.
If the battery gets low, your handheld displays a warning message. If
this occurs, perform a HotSync operation and then recharge the
battery as soon as possible. If your handheld shuts down, you still
have about a week to recharge the battery before you lose the data on
your handheld.