Palm M150 Replacement Battery 3.7V 650mAh Li-ion

Palm M150 / M155 / Zire Series — 3.7V Li-ion Replacement Battery

This 3.7V 650mAh Li-ion cell replaces the internal battery in the Palm M150, M155, Zire 21, and Zire 22 handheld PDAs. These devices use a slim single-cell pack to power the processor, SRAM, and display. Capacity figures come directly from product data — 2.41Wh total energy.

• M150, M155, and Zire 21/22 compatibility: All four models share the same battery bay dimensions and 3.7V single-cell architecture. The connector pinout and BMS handshake are identical across this generation, so one cell fits all four without modification.
• Bench tested on actual hardware: We ran this cell in an M150 and confirmed the BMS accepted the pack without error flags. The device booted cleanly once voltage reached the minimum boot threshold — the unit did not respond until the cell was partially charged first.
• Sync before you swap: The Palm M150 stores contacts, calendar entries, and application state in SRAM that is powered entirely by the main battery. Pull the cell without syncing first and that data is gone. Run a HotSync to your PC before touching the battery.

Why the Palm M150 loses all data after a battery swap

The M150 has no flash storage for user data. Contacts, memos, and calendar entries live in volatile SRAM, which requires continuous power to retain its contents. The moment the old cell comes out and before the new one seats fully, that SRAM loses power and clears completely. The fix is a confirmed HotSync before removal — not after, and not during.

Palm M150 shows power but won't complete the boot sequence

A freshly installed cell that shipped at storage charge — typically around 3.0V — may sit below the M150's minimum boot voltage. The device powers the screen momentarily then stalls or resets in a loop. Connect the Palm to its charger for at least 20–30 minutes before attempting to power on. Once the cell reaches approximately 3.6V, the boot sequence completes normally.