About this replacement
HTC U11 Series — 3.85V Li-Polymer Replacement Battery (B2PZC100)
This is a 3.85V, 2500mAh Li-Polymer cell that replaces the original power unit in the HTC U11 and U11 TD-LTE smartphones. It covers the U-3f and U-3w variants as well. Use the OEM part number B2PZC100 or 35H00271-00M to verify fitment against your original cell before opening the phone.
- U11 platform compatibility: The U11 family shares a common battery bay, connector pinout, and BMS handshake across its regional variants — TD-LTE, U-3f, and U-3w. The voltage rail is identical across all, so one cell covers the full lineup without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a U11 unit. The BMS accepted the cell on first connection, charge current ramped correctly, and the protection circuit tripped at the expected low-voltage cutoff without requiring a manual reset.
- First-cycle fast charge protocol: On first use after installation, disable HTC's fast charging and run one complete discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated coulomb counter.
Sudden shutdown at 20–30% on the U11 after a cell swap
The U11's fuel gauge IC stores a discharge curve from the old cell. When a new cell is fitted, the IC still references that old curve. At around 20–30% reported charge, the new cell's actual voltage drops below what the modem and display demand under load — even though the gauge still shows charge remaining. The phone cuts out because the cell cannot sustain voltage under that current draw, not because it is empty. One full slow discharge to auto-shutdown followed by a full charge resets the coulomb counter and clears the mismatch. After that cycle, shutdowns at inflated percentages stop.
USB-PD fast charge not triggering on the first cycle after replacement
After a cell swap, the U11's charge IC sometimes defaults to standard 5V charging on the first cycle. This happens because the BMS on the new cell has not yet completed its initial handshake with the phone's power delivery negotiation logic. It is not a fault with the charger or the USB-C port. Plug in, let the first full charge complete at standard rate, then disconnect and reconnect — fast charge resumes normally once the BMS handshake clears. If it does not resume, check that the charger outputs at least 9V/1.67A to meet the U11's fast charge threshold.