About this replacement
Canon C300 Mark I / EOS C100 Series — 7.4V Li-ion Replacement Battery
This 7.4V 5200mAh Li-ion cell replaces the OEM BP-955 battery in the Canon C300 Mark I, EOS C100, EOS C100 Mark II, GL2, and 13 additional compatible bodies. It matches the original voltage rail and connector format used across Canon's cinema and prosumer camera lineup. Capacity is drawn from product specification at 38.48Wh.
- C300 / C100 platform fit: These bodies share the same BP-9xx battery slot, contact pinout, and BMS handshake protocol — one cell format covers the full range from the GL2 through the C300 Mark I without adapter or modification.
- Bench tested on actual hardware: We ran this cell through the Canon C100 Mark II body and OEM charger. The BMS handshake completed on first charge cycle, battery-remaining percentage displayed correctly, and no over-voltage flags were triggered on the protection circuit.
- First-install charge cycle on Canon cinema bodies: Insert the new cell and run one full charge directly inside the camera body before heading to set. Canon's BMS on the C300 and C100 series maps its battery-remaining display against a charge cycle performed in-body — skipping this step can cause the indicator to report inaccurate remaining capacity from the first use.
Why the C300 Mark I rejects a third-party cell on first install
Canon cinema bodies authenticate the battery pack through a multi-pin contact check and a brief BMS handshake at power-on. A new third-party cell without a prior charge cycle can fail this check, triggering a no-battery or incompatible-battery warning even when the cell is fully charged. The fix is straightforward: place the battery in the OEM charger or camera body and run one complete charge from empty before inserting it cold into a powered camera. After that first cycle, the body accepts the cell normally and the indicator maps correctly.
Battery percentage jumping erratically on the C100 display
This happens when the camera's internal discharge-curve map doesn't align with the new cell's actual voltage-threshold profile. Canon's indicator firmware reads voltage steps and converts them to percentage brackets — a replacement cell with a slightly different discharge curve hits those voltage thresholds at different points, causing the display to jump in large increments rather than count down smoothly. Run two full charge-discharge cycles through the camera body to let the BMS recalibrate. After the second cycle, the readout should track within a few percentage points of actual remaining charge, and voltage at the low warning threshold should sit near 6.4V.