Emporia Elson SL900 Replacement Battery 3.7V 550mAh Li-ion

Emporia Elson SL900 — 3.7V Li-ion Replacement Battery (BTY26153ELSON/STD)

This is a 3.7V Li-ion cell rated at 550mAh (2.04Wh), built to the same form factor as the original BTY26153ELSON/STD. It fits the Elson SL900 and Elson SL900A. Swap it in when the original cell no longer holds a useful charge or fails to power on.

• SL900 and SL900A compatibility: Both models use the same 3.7V single-cell architecture with the same connector pinout and BMS handshake. The cell dimensions are 41.65 × 38.73 × 5.28mm — measure your original before installing if you are unsure which variant you have.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the SL900 platform and confirmed the BMS accepts the cell, reports voltage correctly, and does not trigger a protection cutoff under normal screen and modem load.
• First-cycle calibration tip: After installing, disable fast charging and run one full discharge-charge cycle before normal use. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.

Why the SL900 reports wrong battery percentage after a cell swap

The fuel gauge IC on the SL900 stores a charge curve learned from the original cell. When you fit a new cell, that stored curve no longer matches the actual discharge profile. The phone reads the voltage and maps it to the old curve, so the percentage shown can be off by 10–20%. One full discharge down to automatic shutdown, followed by a full charge to 100%, forces the coulomb counter to reset its baseline against the new cell. After that cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or display pulls a brief high-current spike that the cell cannot sustain at that state of charge. The cell voltage dips below the BMS cutoff threshold — typically around 3.0V — and the phone shuts off even though the gauge still shows charge remaining. It is more common on the first few cycles before the fuel gauge IC has recalibrated. Run two full discharge-charge cycles; if shutdowns persist beyond that, check that the battery connector is fully seated and making clean contact.