Telstra Velocity 4G Replacement Battery BH39100 3.7V 1600mAh

Telstra Velocity 4G — 3.7V Li-ion Replacement Battery (BH39100)

This is a 3.7V, 1600mAh Li-ion battery for the Telstra Velocity 4G smartphone. It replaces OEM part numbers BH39100, 35H00167-00M, 35H00167-03M, and 35H00167-01M. If your Velocity 4G is shutting down unexpectedly, not holding charge, or failing to power on, this cell replaces the original unit directly.

• Velocity 4G compatibility: All four OEM part numbers listed above share the same 3.7V single-cell Li-ion platform, connector pinout, and BMS handshake profile used across Velocity 4G production runs. The revision codes (00M, 01M, 03M) reflect manufacturing batches, not electrical changes — one cell fits all.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Velocity 4G platform and monitored BMS communication. The protection circuit responded correctly to charge termination, over-discharge cutoff, and thermal thresholds throughout testing.
• Fuel gauge recalibration on first use: After installation, disable any fast-charge mode and run one full discharge-to-charge cycle at standard current. This lets the phone's fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the Velocity 4G after a cell swap

A new Li-ion cell has a slightly different internal resistance profile than the aged cell the phone's fuel gauge was trained on. Under peak load — mobile data, screen-on, GPS active simultaneously — the voltage drops faster than the gauge predicts, and the BMS trips the cutoff before the displayed percentage reaches zero. The phone reads 25% but the actual cell voltage has already fallen below the BMS cutoff threshold of around 3.0V under load. One complete slow discharge-charge cycle recalibrates the coulomb counter and eliminates this mismatch. After that cycle, percentage readings and actual cutoff voltage align correctly.

Battery percentage jumping erratically in the first few days after replacement

The Velocity 4G uses a fuel gauge IC that builds its state-of-charge model from discharge history. When a new cell replaces a degraded one, the IC has no valid reference curve for the new cell's capacity and internal resistance — so it interpolates badly, producing percentage jumps of 5–15% in either direction. This is not a fault with the replacement cell. Run two full discharge cycles — drain until the phone shuts off automatically, then charge uninterrupted to 100% — and the gauge IC will rebuild its model. Jumps should resolve by the end of the second cycle.