BI39100 HTC Titan Compatible Battery 3.8V 1400mAh

HTC Titan X310E — 3.8V Li-ion Replacement Battery (BI39100)

This is a 3.8V, 1400mAh Li-ion cell for the HTC Titan and Titan X310E — Windows Phone devices that share the same battery bay and connector. It also fits the Sensation XL (X315E) and several other HTC models listed in the compatibility table. Capacity is 1400mAh (5.32Wh), matching the original OEM specification.

• Titan and Sensation XL compatibility: The Titan X310E and Sensation XL X315E both use the BI39100 cell because HTC standardised the battery footprint, connector pin-out, and BMS handshake across this generation of Windows Phone and Android hardware. The same physical dimensions (51.28 × 50.95 × 5.55mm) and thermistor line allow the charge IC on each device to read cell temperature correctly.
• Bench tested on actual hardware: We cycled this cell on the Titan platform and confirmed the BMS communicates charge state correctly to the OS. The protection circuit trips at the expected undervoltage threshold, and the charge IC accepted the cell without flagging an authentication error on initial power-up.
• Fuel gauge recalibration on first install: On first use after installation, disable fast charging for one full discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins — skipping this step often causes erratic percentage readings for the first several cycles.

Why the Titan reports wrong battery percentage after a cell swap

The HTC Titan uses a coulomb-counter fuel gauge IC that builds its capacity model against the original cell over hundreds of cycles. When you install a new cell, the IC still references that old discharge curve. The result is percentage readings that lag, jump, or plateau — especially in the 40–80% range. One complete discharge to auto-off followed by an uninterrupted charge to 100% forces the IC to recalibrate against the new cell. After two or three full cycles, the reported percentage tracks actual capacity accurately.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops below the modem or display's minimum rail voltage under load — even though the fuel gauge still shows charge remaining. The fuel gauge reads open-circuit voltage, not loaded voltage, so it misses the voltage cliff. Under peak modem transmission or screen brightness, current draw spikes and the cell can't hold voltage above the BMS cutoff threshold. Run one full calibration cycle first; if shutdowns persist, check that resting cell voltage after a full charge reads at least 4.15V — anything lower points to a cell that didn't fully accept the first charge.