About this replacement
Palm Treo Pro / Treo 850 Series — 3.7V Li-ion Replacement Battery (3343WW)
This is a 3.7V, 2400mAh Li-ion cell for the Palm Treo 850, Treo 850w, Treo Pro, and Drucker. It replaces OEM part numbers 3343WW, 157-10105-00, 35H0014-00M, and CM-2. The battery powers the device's processor, display, wireless radio, and RAM-backed application state.
- Treo 850, 850w, Treo Pro, and Drucker fit: These devices share the same 3.7V single-cell architecture, battery footprint, connector pinout, and BMS handshake protocol — one cell covers the full group without modification.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on a Treo Pro. The BMS handled charge termination correctly and held steady voltage under radio-active data loads without tripping low-voltage cutoff prematurely.
- RAM data protection before swap: Sync all open data to your PC or Exchange server before removing the battery. The Treo 850 series stores active application state and unsaved data in volatile SRAM — it is powered directly by the main cell, and a full power removal wipes it instantly.
Why the Treo 850 loses contacts and calendar data on battery removal
The Treo 850 uses SRAM for active storage, which requires continuous power to retain data. When the battery drops out — even briefly — that memory clears. Unlike flash-stored data, anything not synced to a host or written to persistent storage is gone permanently. Always run ActiveSync or a Palm Desktop sync before pulling the cell, and verify the sync completed before disconnecting.
Treo 850 stuck on boot loop or black screen after new battery installed
A freshly shipped Li-ion cell may arrive at 30–50% state of charge, which is sometimes below the minimum voltage the Treo's boot sequence requires to initialise the radio and OS loader. The device stalls partway through boot or shows nothing at all. Connect the charger before attempting to power on and let the cell reach at least 3.6V. Once the charge LED activates and holds steady, attempt a normal boot.