About this replacement
Sony DCR-SR40 / DCR-HC17 Series — 7.4V Li-ion Replacement Battery (NP-FP50)
This is a 7.4V, 750mAh Li-ion battery pack replacing the NP-FP50 in Sony Handycam camcorders. It fits the DCR-SR40, DCR-DVD703E, DCR-HC17, DCR-DVD602E, and 96 additional models sharing the same FP-series battery slot. The NP-FP30 and NP-FP51 are also covered by this cell.
- FP-series platform fit: Sony's compact Handycam lineup from this era shares a common 7.4V battery rail and identical connector pinout across the FP30, FP50, and FP51 variants. The BMS communicates capacity data over the same data line, so one cell covers the full range.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a DCR-series body. The BMS accepted the cell without error flags, held voltage above 6.8V through the discharge curve, and the camera's remaining-battery indicator tracked consistently.
- First-use charge cycle on the DCR-SR40: Run the first charge from inside the camera body or the OEM charger before shooting. The DCR-SR40's BMS maps its remaining-battery display to a discharge curve it calibrates on the first cycle — skipping this step causes the indicator to drop erratically mid-session.
Sony Handycam BMS rejecting a third-party cell on first install
Sony's FP-series BMS runs an authentication handshake on power-up. A new third-party cell sometimes fails this check and triggers a "battery info" or "incompatible battery" flag on the LCD. This is a communication timing issue, not a cell fault. Power the camera off, remove the battery, reinsert it, and power back on. If the flag persists, place the battery in the OEM charger for one full charge cycle before inserting it into the body — this initialises the cell's BMS state and resolves the handshake.
Battery percentage dropping suddenly from 50% to empty during recording
This happens when the camera's fuel gauge is calibrated to the original cell's discharge curve and the replacement cell has a slightly different voltage taper. The camera reads a voltage threshold it associates with a nearly empty cell and cuts the display accordingly, even if actual charge remains. Running one full charge-to-empty cycle allows the BMS to remap its thresholds to the new cell. After that single calibration cycle, the percentage readout stabilises across the discharge range.