About this replacement
Icom IC-M94D / IC-M94DE — 7.4V Li-ion Replacement Battery (BP-306)
The BP-306 is a 7.4V, 2300mAh lithium-ion battery pack for the Icom IC-M94D and IC-M94DE compact VHF marine transceivers. These handheld radios are used for on-water communication — DSC distress calling, Class D MMSI operation, and standard channel monitoring. Capacity figure matches the original specification from product data: 2300mAh (17.02Wh).
- IC-M94D and IC-M94DE compatibility: Both models run the same 7.4V power rail, use the same connector footprint, and share the same BMS handshake protocol — a single BP-306 pack covers both variants without modification.
- Bench tested on actual hardware: We ran the pack through charge acceptance and PTT transmit-load cycles on the IC-M94D dock. The BMS held the voltage rail steady during sustained TX bursts and did not trigger overcurrent cutoff under normal channel 16 transmit loads.
- First insertion into the charger dock: If the dock LED shows a fault on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The IC-M94D dock requires a clean contact cycle to complete the BMS handshake before it begins charging.
Why the IC-M94D cuts out mid-transmission on a new BP-306
New lithium-ion cells ship at storage voltage — typically around 3.6–3.7V per cell, not full charge. When the IC-M94D draws transmit current at storage voltage, the BMS may read the combined voltage sag as a low-cell event and cut output before the radio completes the TX cycle. This is not a faulty pack. A full charge cycle before first use brings both cells to 4.2V each, which gives the BMS enough headroom to sustain the transmit current spike without triggering cutoff.
Bar indicator showing fewer bars than expected after inserting a new BP-306
The IC-M94D uses a voltage-threshold bar indicator — each bar corresponds to a voltage band, not a percentage. A pack at storage voltage sits in the lower threshold bands, so the display shows one or two bars even though the cell capacity is full and unused. This is not a capacity defect. Charge the pack fully in the dock until the LED goes green, then power on the radio — the bar indicator will read correctly once the cells are at 4.2V per cell.