AT&T Inspire 4G Replacement Battery 3.7V 1050mAh

AT&T Inspire 4G — 3.7V Li-ion Replacement Battery (35H00141-00M)

This is a 3.7V, 1050mAh lithium-ion replacement battery for the AT&T Inspire 4G smartphone. It fits directly in place of the original cell and covers all OEM part numbers in this device family: 35H00141-00M, 35H00141-02M, 35H00141-03M, BD26100, and BA S470. Replace it when your original battery swells, stops holding charge, or shuts down unexpectedly under load.

• Inspire 4G compatibility: All five OEM part numbers above share the same 3.7V cell format, connector pinout, and BMS handshake on the Inspire 4G. HTC revised the part number across production runs without changing the physical or electrical spec, so these are interchangeable on the same hardware.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Inspire 4G platform. The BMS accepted the charge handshake on first connection, and the protection circuit tripped correctly at the low-voltage cutoff threshold — no false overcurrent events during normal draw.
• Fuel gauge recalibration on first use: On first use after installation, run one full discharge down to auto-shutdown, then charge uninterrupted to 100% before using the phone normally. This gives the fuel gauge IC a complete discharge curve against the new cell so percentage readings stay accurate from cycle two onward.

Sudden shutdown at 20–30% on the Inspire 4G

This happens when the cell's internal resistance rises enough that voltage drops sharply under modem or display load — even though the fuel gauge still shows charge remaining. The phone's low-voltage protection trips before the gauge catches up. On a new replacement cell, this most often occurs before the first full calibration cycle is complete. Run one full discharge to auto-shutdown and recharge to 100% without interruption; the fuel gauge IC will map the new cell's voltage curve and the cutoffs will align correctly. After calibration, the shutoff threshold should track closer to 3.4–3.5V under load.

Phone won't power on after sitting in storage with a flat battery

If the Inspire 4G was stored discharged for weeks or months, the cell voltage may have dropped below 2.5V — the threshold where the BMS locks out to prevent damage. The phone will show no response and may not even display a low-battery screen. Connect it to a wall charger (not a PC USB port) and leave it for 20–30 minutes without pressing anything. The charge IC will trickle current into the cell to bring voltage above the BMS unlock threshold, after which normal charging resumes — target a full charge to 4.2V before first use.