About this replacement
Icom IC-M71 / IC-M72 / IC-M73 Series — 7.4V Li-ion Replacement Battery (BP-245)
This 7.4V 2100mAh Li-ion battery replaces the BP-245, BP-245N, and BP-245H packs used in the Icom IC-M71, IC-M72, IC-M73, and IC-M73 Euro portable marine transceivers. It slots into the same battery compartment and uses the same contact layout as the original Icom pack. Voltage and capacity match the OEM spec exactly — 7.4V, 2100mAh (15.54Wh).
- IC-M71 / IC-M72 / IC-M73 platform fit: These four models share the same battery bay dimensions, contact strip geometry, and BMS handshake protocol. One battery covers the full range because Icom standardised the BP-245 form factor across this marine VHF line.
- Bench tested on actual hardware: We cycled this pack through transmit loads on the IC-M71 and confirmed the BMS held voltage above the radio's low-battery cutoff threshold under sustained PTT draws. No overcurrent trips occurred during the full test sequence.
- Marine dock contact care: Salt air and moisture on the gold contact strip will cause a fault LED on first dock insertion. Before seating the pack in the charger, wipe the contact strip with a dry cloth — the Icom dock requires a clean contact surface to complete the BMS handshake and begin the charge cycle.
Why the IC-M71 cuts out mid-transmission on a fresh BP-245
A new Li-ion cell ships at storage voltage — typically around 3.7V per cell, giving roughly 7.4V at the pack terminals. On the IC-M71, that voltage is right at the edge of the radio's transmit threshold. When PTT is pressed, the transmit current spike causes a brief voltage sag that the BMS reads as an undercurrent event. The radio drops out because the BMS has tripped, not because the cell is faulty. Run one full charge cycle before the first transmission test — the pack needs to reach its operating voltage range of 8.2–8.4V to sustain transmit current without tripping.
Bar indicator showing one fewer bar than expected on a new BP-245
The IC-M71 reads battery level by measuring pack voltage against fixed thresholds — it does not track charge capacity. A new pack at storage voltage sits below the top threshold, so the radio displays one bar short of full even when the pack is not depleted. This is a voltage-threshold display behaviour, not a defective cell. Charge the pack fully in the Icom dock until the charge indicator clears, then reinsert — the bar indicator will reflect the correct full-charge voltage of approximately 8.4V.