Olympus BLH-1 Mirrorless Camera Replacement Battery 7.4V 2250mAh

Olympus E-M1 Mark II — 7.4V Li-ion Replacement Battery (BLH-1)

This is a 7.4V, 2250mAh Li-ion replacement for the Olympus BLH-1 battery. It fits the Olympus OM-D E-M1 Mark II mirrorless camera. The cell powers the sensor, autofocus system, and electronic viewfinder through the same voltage rail as the original.

• E-M1 Mark II compatibility: The E-M1 Mark II uses a single BLH-1 cell on a 7.4V rail with a BMS handshake for battery-remaining display. This cell matches that voltage and the connector pinout. The BMS reads state-of-charge from the cell's discharge curve — a mismatch here causes erratic percentage readouts.
• Bench tested on actual hardware: We ran this cell through the E-M1 Mark II body and an OEM HLD-9 grip. The BMS accepted the cell without error flags, and cutoff triggered correctly at low-voltage threshold rather than throwing a false-empty warning mid-shoot.
• First charge on the E-M1 Mark II: Complete the first full charge cycle inside the camera body or OEM BCH-1 charger — not a third-party USB charger. The E-M1 Mark II BMS maps its battery-remaining indicator against an internal calibration cycle. Skipping this step often causes the percentage display to jump or read inaccurately from the start.

Why the E-M1 Mark II shot count drops under sustained 4K or continuous AF

The E-M1 Mark II pulls current from four major draws simultaneously during video or burst shooting: the sensor, the image processor, the 5-axis in-body stabilisation, and the phase-detect AF system. Combined draw during 4K recording is significantly higher than during single-shot stills. The rated shot count is measured under CIPA conditions — mostly single-frame stills with the EVF off — not continuous recording. Switching to a smaller JPEG format or reducing AF sensitivity in the menu will lower current draw and extend each charge.

Battery percentage jumping on the E-M1 Mark II display after fitting a new cell

The E-M1 Mark II maps its battery-remaining percentage against a stored discharge-curve profile from the BMS calibration cycle. A new, uncalibrated cell has a slightly different resting voltage at each state-of-charge point, so the camera misreads percentage at certain thresholds. This is not a faulty cell — it is a calibration gap. Run one full discharge down to camera cutoff, then charge to 100% inside the camera body or BCH-1 charger. After that cycle, the percentage display stabilises.