Midland H3 Replacement Battery 3.7V 900mAh Li-ion

Midland H3 / H5 — 3.7V Li-ion Replacement Battery

This 3.7V 900mAh (3.33Wh) lithium-ion cell replaces the internal battery in the Midland H3 and H5 action cameras. Both models use the same compact cell format — 32.77 × 29.16 × 10.89mm — and share the same voltage rail. If the original battery no longer holds a charge or the camera shuts down mid-recording, this cell is a direct swap.

• H3 and H5 compatibility: Both cameras run the same 3.7V single-cell architecture with identical connector pinout and physical footprint. One cell fits both bodies without modification.
• Bench tested on actual hardware: We cycled this cell through the Midland camera body and monitored the BMS handshake on first charge. The cell accepted a full charge cycle without cutoff events, and the protection circuit responded correctly to overdischarge simulation.
• First-install charge protocol: Insert the new cell and run a complete charge cycle through the camera body or OEM charger before shooting. Some Midland camera firmware requires this cycle to map the new cell's discharge curve and display battery level accurately.

Why the H3 battery indicator jumps erratically after a cell swap

The H3 maps battery percentage against a fixed voltage-threshold table calibrated to the original cell's discharge curve. A fresh replacement cell discharges at a slightly different rate until it has been cycled once or twice. During that break-in period, the camera may report 80% one moment and drop to 20% shortly after. This is a firmware mapping issue, not a cell fault. Run two full charge-discharge cycles through the camera body and the indicator will track correctly against the new cell's actual curve.

Camera shuts off mid-recording even with a recently charged cell

Sustained 1080p video recording draws continuous current from the sensor, image processor, and stabilisation system simultaneously. Under that combined load, a partially degraded or improperly seated cell can sag below the BMS undervoltage cutoff threshold — typically around 3.0V on Midland's protection circuit — triggering an abrupt shutdown. Check the cell is fully seated and the contacts are clean. Charge to full, then verify the cell voltage reads at or above 4.1V before recording a long session.