Mitsubishi BY-M1 Replacement Battery 6V 2100mAh Ni-MH

Mitsubishi BY-M1 / BY-M2 / BY-U1 / BY-U2 — 6V Ni-MH Replacement Battery

This is a 6V 2100mAh Ni-MH replacement battery for Mitsubishi digital cameras including the BY-M1, BY-M2, BY-U1, and BY-U2. It matches the original voltage and chemistry so the camera body and BMS receive the correct signal. Capacity is sourced from the product specification at 2100mAh (12.6Wh).

• BY-M1, BY-M2, BY-U1, BY-U2 platform fit: These models share the same 6V Ni-MH power rail and connector format. The BMS in each body expects a Ni-MH discharge curve — swapping chemistry breaks the voltage-remaining map and causes false low-battery readings.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a camera-equivalent 6V load. The BMS handshake completed without rejection, and the cell held within expected voltage range across the full discharge profile.
• First-install charge cycle on BY-M1 and BY-U series bodies: Run one full charge cycle through the OEM charger or camera body before shooting. These Mitsubishi bodies map battery-remaining display to a calibrated Ni-MH discharge curve — a cold, uncalibrated cell will show erratic percentage readings until that first full cycle completes.

Dead battery indicator on the BY-M1 with a partially charged replacement cell

The BY-M1 reads remaining charge by tracking voltage thresholds across the Ni-MH discharge curve. A new cell that hasn't been through a full calibration cycle presents a slightly different resting voltage than the body expects at any given charge level. The camera interprets this mismatch as a depleted cell and throws the dead-battery indicator even when the cell has usable capacity. Running one complete charge-to-full cycle in the OEM charger before use resets that baseline and clears the false reading.

Battery percentage jumping erratically during a shoot

Ni-MH cells have a flatter discharge curve than Li-ion, and the BY-series indicator firmware is calibrated tightly to the original cell's curve shape. A replacement cell with a slightly different internal resistance will cause the voltage under load to dip and recover in ways the indicator wasn't mapped to handle. The result is percentage numbers that jump — sometimes 20 or 30 points — between shots. This settles after two to three full charge-discharge cycles as the BMS learns the new cell's actual behaviour. If it doesn't stabilise after three cycles, check resting voltage with a multimeter — it should read at or above 6.0V fully charged.