HTC Titan BI39100 Replacement Battery 3.8V 1650mAh

HTC Titan / Sensation XL Series — 3.8V Li-ion Replacement Battery (BI39100)

This is a 3.8V, 1650mAh Li-ion cell built to replace the original BI39100 battery in the HTC Titan, Titan II, X310E, and Sensation XL. It slots into the same battery bay and connects through the same three-contact interface. Capacity matches OEM spec at 6.27Wh.

• Titan and Sensation XL platform fit: Both the Titan and Sensation XL share the same battery form factor, voltage rail, and contact pinout. One cell covers the full platform because HTC standardised the bay dimensions and BMS handshake across this hardware generation.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Titan unit. The BMS accepted the cell without error flags, charge termination triggered correctly at 4.2V, and the protection circuit tripped cleanly on an over-discharge test at 2.5V.
• Fuel gauge recalibration on first install: Disable fast charging and run one full discharge down to automatic shutdown, then charge uninterrupted to 100%. This gives the fuel gauge IC a clean reference curve against the new cell before any high-current cycle pushes current into an uncalibrated state register.

Sudden shutdown at 20–30% on the HTC Titan after a cell swap

The Titan's fuel gauge IC stores a discharge curve calibrated to the original cell's internal resistance profile. A new cell has a different impedance, so the reported percentage diverges from the actual remaining charge. Under modem load — a call, LTE handoff, or background sync — the phone draws a current spike the fuel gauge did not anticipate, the cell voltage drops below the shutdown threshold briefly, and the device cuts out. This is not a faulty cell. One full uninterrupted discharge-to-shutdown followed by a full charge resolves it by forcing the IC to relearn the curve against actual cell behaviour.

Phone feels warm near the battery during the first few charges

A fresh high-impedance cell generates more heat than a run-in cell at the same charge current because internal resistance converts more energy to heat during the initial cycles. The Titan's charge IC does not throttle current on first use — it applies the same charge profile regardless of cell age. The warmth drops off after two to three full cycles as internal resistance settles. If the case stays warm past the third cycle or charge termination is not occurring at 4.2V, check that the battery contacts are fully seated and clean.