About this replacement
HTC One M9 — 3.8V Li-Polymer Replacement Battery (B0PGE100)
This 3.8V, 2840mAh lithium-polymer cell replaces the OEM battery in the HTC One M9 and One M9+. It fits devices where the original cell has degraded through repeated charge cycles and can no longer sustain voltage under normal screen and modem load. Part number B0PGE100 confirms fitment across the M9 family.
- M9 and M9+ family fitment: The M9 and M9+ share the same battery bay dimensions, connector pinout, and BMS communication protocol — which is why one cell covers both. The 93.00 × 63.03 × 3.20mm form factor matches the chassis recess exactly, and the thermistor line on the connector carries cell temperature data to the Qualcomm charge IC on the board.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an M9 board. The BMS handshake completed on first connection, the charge IC accepted the cell without fault flags, and the coulomb counter began tracking state-of-charge within the first partial cycle.
- First-cycle fast charge hold-off: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate its discharge curve against the new cell before the charge IC pushes high current into an uncalibrated state-of-charge model. Standard USB charging is enough for cycle one.
Sudden shutdown at 20–30% on the HTC One M9 after a cell swap
The HTC One M9 uses a coulomb counter paired with a voltage-based fuel gauge model calibrated to the original cell's discharge curve. When you fit a new cell, that model is still referencing the old curve. Under high-draw conditions — LTE modem, screen at full brightness, GPS active — the new cell's actual terminal voltage drops faster than the gauge predicts, and the system hits the low-voltage cutoff while the display still shows 20–30%. One full slow discharge to automatic shutoff followed by an uninterrupted charge to 100% resets the fuel gauge baseline against the new cell.
Phone warm near the battery during the first few charges
A new lithium-polymer cell typically has higher internal impedance than a well-cycled original. During the first few charge sessions, the charge IC on the M9 board pushes current through that higher-impedance cell, and more energy converts to heat at the cell surface before impedance drops with conditioning. This is normal and reduces after three to five full cycles. If the phone remains warm beyond cycle five or the charge IC triggers a thermal throttle — indicated by charging slowing significantly mid-cycle — check that the replacement cell's NTC thermistor connector is fully seated, as a poor connection sends incorrect temperature data to the charge IC.