HTC ChaCha BA S570 Replacement Battery 3.7V 1200mAh

HTC ChaCha A810E — 3.7V Li-ion Replacement Battery (BA S570)

This 3.7V 1200mAh Li-ion battery fits the HTC ChaCha and ChaCha A810E smartphone. It replaces OEM part numbers BA S570, BH06100, 35H00156-00M, and 35H00155-00M. The ChaCha's compact QWERTY form factor uses a slim 51 x 36 x 6mm cell — this unit matches that footprint exactly.

• ChaCha platform fit: The ChaCha, A810E, PH06130, and G16 all share the same battery bay dimensions, connector pinout, and 3.7V nominal voltage rail. The BMS on each of these models communicates through the same three-pin interface, so the cell seats and handshakes without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the ChaCha platform. The BMS accepted the cell on first connection, charge termination triggered correctly at 4.2V, and the protection circuit responded to over-current draw as expected.
• Fuel gauge recalibration on first use: After installing this cell, disable any fast-charge adapter for the first complete discharge-to-charge cycle. The ChaCha's fuel gauge IC needs one full cycle against the new cell's discharge curve before its coulomb counter reads accurately. Skip this step and the percentage display will drift.

Why the ChaCha reports wrong battery percentage after a cell swap

The ChaCha uses a fuel gauge IC that builds its capacity model from accumulated charge and discharge data on the original cell. When you fit a new cell, that stored model no longer matches the actual discharge curve. The IC continues applying the old curve, so the percentage it reports diverges from true state of charge. One complete slow discharge down to automatic shutdown, followed by a full charge to 4.2V, resets the coulomb counter reference point and realigns the gauge to the new cell.

Sudden shutdown at 20–30% on the ChaCha after fitting a new cell

This happens when the fuel gauge IC is still calibrated to a degraded cell with a compressed voltage curve. The new cell hits a steeper voltage drop under modem or screen load than the IC anticipates, and the BMS trips the low-voltage cutoff before the displayed percentage reaches zero. It is not a faulty cell — it is a calibration mismatch. Run one full discharge cycle without interruption and let the phone shut itself off, then charge uninterrupted to 4.2V. After that cycle the shutdowns stop.