About this replacement
Sony Portable Reader PRS-500 / PRS-505 — 3.7V Li-Polymer Replacement Battery (1-756-769-11)
This 3.7V 680mAh Li-Polymer cell replaces the original battery in the Sony Portable Reader PRS-500, PRS-505, PRS-505SC/JP, and PRS-505/RC. It matches the OEM part numbers 1-756-769-11, LIS1382(J), and 8704A41918. At 52 x 34 x 4mm, it fits the original battery bay without modification.
- PRS-500 and PRS-505 series compatibility: Both models share the same 3.7V Li-Polymer cell format, connector pinout, and BMS handshake protocol. Sony used the same battery platform across the PRS-505 regional variants, so one cell covers the full lineup listed above.
- Bench tested on actual hardware: We cycled this cell through the PRS-500's charge controller and confirmed the BMS accepts the cell without fault flags. Charge termination triggered correctly at 4.2V and the device booted cleanly from a cold state.
- Post-swap charge cycle on e-ink firmware: The PRS-500 and PRS-505 firmware calibrates battery percentage display against a full charge cycle. After installing, connect via USB and let the device charge to 100% before use — skipping this step causes the battery indicator to read inaccurately for the first several sessions.
Why the PRS-500 battery percentage jumps or reads wrong after a cell swap
Sony's e-reader firmware stores a charge model built from the old cell's degraded capacity. When a fresh cell goes in, the stored model no longer matches actual cell behaviour, so the percentage display skips or reads high then drops suddenly. The fix is a full charge-to-discharge-to-charge cycle, which forces the firmware to rebuild its capacity estimate against the new cell. After two full cycles, the percentage display stabilises. No factory reset is needed — the calibration happens automatically through normal use once the first full charge completes.
PRS-500 showing low battery warning immediately after installing a new cell
Replacement cells ship at storage voltage — typically 3.6V to 3.7V — to slow self-discharge in transit. The PRS-500's low-battery threshold sits close to that range, so the device can flag a warning the moment it boots on a fresh cell. This is a voltage threshold trigger, not a cell fault. Connect the device to a USB charger immediately after installation and leave it for a full charge cycle before attempting to use it. Once the cell reaches 4.2V and the charge controller terminates, the warning clears and the firmware locks on to the correct charge floor.