Q: What batteries does the Palmtop use and how long do they last?

A: The 100/200LX uses 2 standard AA cells, either Alkaline or NiCd. It also uses a miniature lithium button battery for memory backup when the main batteries fail. Battery life varies a lot, based on how much you use the machine, what kind of PC Card you use, how much you use the serial and IR ports, how good your batteries are, etc. As a rough guess, several users have reported needing to recharge their NiCd's approximately once a week, when running it a few hours a day with a Flash card. Users have reported in excess of a month of regular usage from fresh high-capacity lithium AA cells, down to an hour or less with a power-sucking PC Card modem and NiCds. The HP manual claims that for typical use without the AC adapter, fresh Alkaline batteries should last from 2 to 8 weeks. Rechargeable batteries ... will get less life ... (see page A-2 of The HP 100LX User's Guide).

Although the manual only recommends alkaline or NiCds, users have reported success with lithium AA cells. Lithium cells have a much longer shelf life and running life than alkalines. Setting the machine up for alkalines works for lithiums. Others have cautioned that inserting lithium cells backwards can permanently damage the machine, and the discharge curve for lithiums is very steep, leaving little time between the first low battery warning and completely dead batteries.

The 100/200LX can charge installed NiCds by simply plugging in an AC adapter and selecting the option from the setup application. No separate charger is needed.

Rechargeable alkaline or NiMH batteries can be used, just like regular alkalines. However, to charge the alkalines you must take them out of the 100/200LX and put them in a charger specially designed for rechargeable alkalines. Although the Palmtop's built-in recharging circuitry is designed for NiCds, users have reported success recharging NiMH batteries in the Palmtop. Some users recommend charging NiMH batteries twice (charge for 6 hours, disconnect the adapter and reconnect it to restart the recharging cycle, and charge the batteries for another 6 hours). Others report that a once-a-week overnight charge is all that's needed.