HTC 7 Trophy Replacement Battery 3.7V 3000mAh 35H00134-17M

HTC 7 Trophy / Spark / T8686 — 3.7V Li-ion Replacement Battery (35H00134-17M)

This is a 3.7V, 3000mAh Li-ion cell replacing OEM part 35H00134-17M in the HTC 7 Trophy, Spark, and T8686 smartphones. These three models share the same physical footprint and battery connector, so one cell covers all three. Capacity is 11.1Wh — listed from product data, not estimated.

• 7 Trophy, Spark, and T8686 compatibility: All three handsets run the same battery bay dimensions (65.00 × 43.90 × 9.20mm), the same 3.7V supply rail, and the same two-contact connector orientation. The BMS handshake is identical across the variant lineup, so no hardware modification is needed.
• Bench tested on actual hardware: We ran the cell through full charge and discharge cycles on a T8686 unit. The BMS accepted charge without tripping over-voltage protection, and the fuel gauge IC tracked state-of-charge through the complete curve without dropout events.
• Fuel gauge recalibration on first use: After fitting this cell, disable any fast-charge accessory for the first complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging begins — skipping this step can leave the coulomb counter misaligned for weeks.

Why the HTC 7 Trophy reports wrong battery percentage after a cell swap

The fuel gauge IC on the HTC 7 Trophy stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual cell chemistry and impedance. The gauge reads state-of-charge against old data, so it can show 40% while the real voltage is already near cutoff. One complete slow discharge to automatic shutdown followed by a full uninterrupted charge resets the learned curve and brings percentage readings back into alignment.

Sudden shutdown at 20–30% on the replacement cell

This happens when the screen backlight and modem transmitter spike simultaneously, pulling current the cell can't sustain at low state-of-charge. Voltage drops below the BMS cutoff threshold — typically around 3.0V — before the fuel gauge has counted down to 0%. It's not a faulty cell; it's the gauge reading high while actual cell voltage collapses under load. After one full calibration cycle, the fuel gauge tracks the voltage cliff accurately and the OS cuts off at the correct percentage.