About this replacement
Toshiba Genio E300 Series — 3.7V Li-Polymer Replacement Battery (LAB503759C)
This is a 3.7V, 1000mAh Li-Polymer battery for the Toshiba Genio E300 line of PDA and Pocket PC handhelds. It replaces OEM part LAB503759C and fits the Genio E300, E310, E330, and E335. The cell measures 60.50 × 36.31 × 5.02mm and slots directly into the original battery bay.
- Genio E300 series compatibility: The E300, E310, E330, and E335 share the same battery footprint, connector pinout, and BMS handshake protocol. One cell covers the full range without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Genio E300 platform. The BMS negotiated correctly, voltage reporting in the system settings matched expected levels, and no fault flags were raised during the test.
- RAM backup before battery removal: Sync all open data to your host computer before pulling the battery. The Genio E300 stores application state and open files in SRAM that is powered entirely by the main cell — cutting power without syncing first will erase unsaved data.
Why the Genio E300 loses contacts and calendar data after a battery swap
The Genio E300 uses battery-backed SRAM as its primary working memory. There is no onboard flash storage holding your active data — the battery is the only thing keeping that memory alive. The moment the cell drops below the SRAM hold voltage, the contents are gone. This is not a fault in the replacement battery; it is the architecture of the device. Always perform an ActiveSync backup to your PC before removing the old cell, then restore after fitting the new one.
Genio E300 stuck on boot screen after fitting new battery
A Li-Polymer cell shipped in storage state may arrive at 3.0V or below, which is under the minimum threshold the Genio E300 boot sequence requires to complete POST. The device powers on, reaches the Toshiba splash screen, and stalls — it is not a firmware or hardware fault. Connect the charger and leave it for at least 30 minutes before attempting to boot again. Once the cell reaches approximately 3.6V, the device will boot normally and proceed to the setup or main screen.