Coinsound E7 Replacement Battery PCT903450 3.7V 1800mAh

Coinsound E7 Series — 3.7V Li-Polymer Replacement Battery (PCT903450)

This 3.7V 1800mAh Li-Polymer cell replaces the original PCT903450 pack in the Coinsound E7, E7 Pro, and OWIN E7 wireless headsets. It restores full charge capacity when the original cell has degraded through repeated cycles. Voltage and connector match the OEM spec exactly.

• E7, E7 Pro, and OWIN E7 compatibility: All three models share the same PCB layout, connector pinout, and 3.7V power rail, which is why they take the same PCT903450 cell. The BMS on each variant reads cell voltage and temperature through the same logic — no firmware difference affects pack recognition.
• Bench tested on actual hardware: We cycled this cell through the E7 base station and confirmed the BMS completed a full charge handshake without throwing a fault. Discharge held steady under combined DECT radio and audio draw with no mid-cycle cutoff.
• First charge in the base station: Seat the headset in the base dock and let it complete a full uninterrupted charge before use. The E7 base logs the new cell during this cycle — skipping it causes the talk-time indicator to read inaccurately until the calibration cycle finishes.

Base station showing a charging error after fitting a new cell

The E7 base station checks for a BMS handshake before it starts the charge cycle. If the new cell ships at storage voltage — typically around 3.6V — the base may flag an error on first dock because it expects a cell already within its normal operating window. Place the headset in the dock, leave it for 10 minutes, then remove and re-seat it. This gives the BMS time to initialise and pass the voltage check, after which the base clears the error and begins charging normally.

Headset cutting out mid-call even after a full charge

The E7 draws current from two sources simultaneously during a call — the DECT radio transmitter and the audio codec. That combined load creates brief current spikes that exceed what a degraded or shallow-cycled cell can deliver without a voltage sag. When cell voltage dips below the BMS cutoff threshold during a spike, the headset drops the call and powers off. After fitting a new cell, run three to five full charge-discharge cycles before judging talk time — capacity improves as the cell conditions. If cut-outs persist past cycle five, confirm the base dock contacts are clean and making firm contact with the headset.