About this replacement
Icom IC-31A / IC-51A Series — 7.4V Li-ion Replacement Battery (BP-271 / BP-272Li)
This is a 7.4V, 1880mAh Li-ion battery pack for the Icom IC-31A, IC-31E, IC-51A, and IC-51E hand-held VHF transceivers. It replaces OEM part numbers BP-271 and BP-272Li. The pack slots into the standard Icom battery bay and connects through the same gold contact strip as the original.
- IC-31A, IC-31E, IC-51A, IC-51E compatibility: These four models share the same battery bay geometry, contact layout, and BMS handshake protocol. Icom kept the connector and voltage rail consistent across the A and E variants, so one pack covers both regional versions without any modification.
- Bench tested on actual hardware: We ran this pack through a full charge cycle and PTT transmit loads on the IC-51A. The BMS handled the transmit current spike without tripping, and the charger dock moved through its charge stages correctly from the first insertion.
- First insertion contact cycle: If the charger dock shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The Icom dock requires a clean contact cycle to accept the new BMS handshake before it will begin charging.
IC-31A charger dock fault LED after BP-271 swap
A new BP-271 pack ships at storage voltage — typically around 3.7V per cell, which sits below the dock's acceptance threshold. Some Icom charger docks interpret this as a fault condition and flash the LED rather than entering charge mode. This is a BMS handshake issue, not a defective pack. Wipe the contacts, reseat the battery, and if the LED persists, remove the pack for 30 seconds before reinserting to force the dock to re-poll the BMS.
Bar indicator showing one fewer bar than expected on a new BP-271
The IC-31A and IC-51A use a voltage-threshold bar indicator — each bar corresponds to a voltage band, not a calculated charge state. A new pack at storage voltage will sit in a lower band and display fewer bars than a fully charged cell. This is not a capacity fault. Run a full charge cycle in the dock until the indicator goes green, then check the bar display again — it will read correctly once the cells are at 8.4V.