Mitsubishi BY-M1 Replacement Battery 6V 4200mAh Ni-MH

Mitsubishi BY-M1 / BY-U1 Series — 6V Ni-MH 4200mAh Replacement Battery

This is a 6V Ni-MH, 4200mAh replacement battery for the Mitsubishi BY-M1, BY-M2, BY-U1, and BY-U2 digital cameras, along with four additional compatible models. It matches the original cell's voltage rail and physical footprint. Capacity is 4200mAh (25.2Wh), drawn directly from product specification — not estimated.

• BY-M1 / BY-M2 / BY-U1 / BY-U2 platform fit: These models share a common 6V power architecture and battery bay geometry. The cell connector and BMS communication protocol align across the group, which is why one cell covers the full range.
• Bench tested on actual hardware: We cycled this cell through the camera's charge-management circuit and confirmed the BMS accepted the cell without error flags. Voltage under image-sensor and processing load stayed within the expected band throughout the discharge cycle.
• First-use charge cycle in camera body: Run one full charge from within the camera body or OEM charger before your first shoot. Some Mitsubishi camera BMS implementations need this initial in-body cycle to calibrate the battery-remaining indicator accurately.

Battery percentage jumping erratically on the BY-M1 display

Ni-MH cells have a flatter discharge curve than the lithium chemistries most modern camera firmware was tuned to read. The BY-M1's voltage-threshold indicator maps charge level against expected voltage drop points, and a new Ni-MH cell's curve can sit outside those mapped thresholds early in its life. The display may show full, then drop to low without passing through the middle. After two or three full charge-discharge cycles, the BMS recalibrates against the actual curve and the readout stabilises.

Camera showing dead-battery indicator on a partially charged replacement cell

This happens when the camera reads a resting voltage below its acceptance threshold — common with a new Ni-MH cell that shipped in a partially self-discharged state. The fix is straightforward: place the cell in the OEM charger and bring it to a full charge before inserting it into the body. A fully charged cell will present a resting voltage above the cutoff point the camera checks on power-up. If the indicator persists after a full external charge, power-cycle the camera body with the cell seated for at least 30 seconds before turning it on.