About this replacement
HTC U Ultra — 3.85V Li-Polymer Replacement Battery (B2PZF100)
This 3.85V, 3000mAh Li-Polymer battery replaces the original cell in the HTC U Ultra and U Ultra TD-LTE (Ocean Note). It matches OEM part numbers B2PZF100 and 35H00269-00M. Capacity figure is taken directly from product specifications, not estimated from web sources.
- U Ultra and TD-LTE variant fitment: Both the standard U Ultra and the TD-LTE (Ocean Note) variant share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell fits across the entire lineup without modification.
- Bench tested on actual hardware: We ran this cell on a U Ultra test unit and confirmed the BMS accepted charge state communication on first cycle, charge IC engaged without fault flags, and the fuel gauge IC reported state of charge correctly after a single full discharge.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell and skews percentage readings.
Sudden shutdown at 20–30% after fitting a replacement cell
The U Ultra's SoC pulls hard on the battery when the modem switches between LTE bands or the display drives peak brightness. A new cell with a slightly different discharge curve hits a voltage cliff earlier than the fuel gauge IC expects. The phone reads 25% but the actual cell voltage has already dropped below the hardware shutdown threshold under load. One full calibration cycle — drain to auto-off, charge uninterrupted to 100% with fast charge disabled — resets the coulomb counter and resolves this.
USB-PD fast charge not engaging on the first charge after swap
After a cell replacement, the U Ultra's charge IC defaults to standard 5V/1A on the first connection while it verifies BMS handshake data from the new cell. Fast charge negotiation via the Quick Charge protocol resumes once the IC has confirmed cell impedance is within range — typically after the first full charge cycle completes. If fast charge still does not engage after that cycle, check that the original HTC wall adapter is in use, since third-party adapters may not complete the proprietary voltage handshake. Confirm the adapter output steps up to 9V during charging to verify fast charge is active.