About this replacement
Heine ML4 LED / mPack Unplugged — 7.4V Li-Polymer Replacement Battery (X-007.99.665)
This 7.4V 1800mAh lithium-polymer battery replaces OEM part numbers X-007.99.665, X-007.99.678, and X-007.99.680 in the Heine ML4 LED headlight system and mPack Unplugged power unit. It is used by ENT specialists, dentists, and surgical professionals who rely on the ML4 LED for diagnostic and procedural illumination. Voltage and capacity match OEM specification exactly — 7.4V, 1800mAh (13.32Wh).
- ML4 LED and mPack Unplugged compatibility: Both devices share the same 7.4V lithium-polymer cell format, connector pinout, and BMS handshake protocol. One battery part number covers both platforms because the power management circuitry is identical across the ML4 LED headlight and the mPack Unplugged mobile power unit.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the ML4 LED platform. The BMS accepted the cell without fault flags, completed voltage verification at startup, and held stable output through the load profile typical of LED driver circuits at clinical brightness levels.
- First-use protocol for medical hardware: After installing this battery, allow the ML4 LED to complete its full power-on self-test without interruption. The BMS runs a voltage and chemistry verification sequence at startup. Cutting power during this window triggers a persistent battery fault that will not clear until the device completes a full reboot with the battery seated.
Why the ML4 LED alarms low battery immediately after a confirmed full charge
The ML4 LED's BMS stores a learned voltage-capacity curve from the previous cell. A new lithium-polymer cell has not yet built that profile, so the BMS compares startup voltage against thresholds calibrated for a degraded OEM cell and flags a mismatch. This is not a fault with the replacement battery — it is the BMS defaulting to a conservative threshold. Run one complete charge-discharge cycle on the device, and the BMS will recalibrate its curve to the new cell's actual resting voltage of approximately 8.35V at full charge.
ML4 LED not powering on after the battery sat unused in storage
Lithium-polymer cells self-discharge at roughly 2–3% per month. If the battery sat uninstalled for several months, its resting voltage can drop below the ML4 LED's BMS recovery threshold — typically around 6.0V for a 7.4V nominal cell — and the device will refuse to power on as a protection measure. Place the battery on the OEM Heine charger for at least 30 minutes before attempting to power on the headlight. If the charger indicator shows activity, the cell is recovering. Once voltage climbs above the recovery threshold, the ML4 LED will boot normally.