About this replacement
Icom IC-31A / IC-51A Series — 7.4V Li-ion Replacement Battery (BP-271 / BP-272Li)
This is a 7.4V, 3300mAh Li-ion battery for the Icom IC-31A, IC-31E, IC-51A, and IC-51E handheld transceivers. These are compact VHF/UHF two-way radios used in portable field and professional communications. The battery slots into the same dock position as the original BP-271 and BP-272Li packs.
- IC-31 and IC-51 platform fit: Both series run the same 7.4V rail, use the same gold-contact connector, and share a BMS handshake protocol — one battery covers both. The BP-271 and BP-272Li OEM references both map to this cell configuration.
- Bench tested on actual hardware: We cycled this pack through full charge and PTT transmit loads on the IC-51 platform. The BMS handled the transmit current spike without tripping, and the dock accepted the pack on first insertion after a contact wipe.
- First insertion on the Icom dock: If the charger dock shows a fault LED on first insertion, remove the battery, wipe the gold contact strip with a dry cloth, and reseat firmly. The Icom platform requires a clean contact cycle to complete the BMS handshake before charging begins.
IC-31A / IC-51A bar indicator showing one fewer bar than expected on a new pack
New Li-ion cells ship at storage voltage — typically around 3.7–3.8V per cell, which puts the pack near 7.5V total. The IC-31 and IC-51 voltage-threshold bar system reads this as one bar below full. The radio is not faulty and the battery is not defective. Run a full charge cycle first; once the pack reaches 8.4V, the bar indicator will read correctly.
Radio cuts out mid-transmission on PTT press with new battery inserted
Pressing PTT draws a hard current spike as the RF stage ramps up — on the IC-51 platform this can exceed 1.5A for a brief moment. If the gold contact strip has residue or oxidation, that spike causes a voltage drop at the terminal that the BMS reads as an overcurrent event and trips. Remove the pack, clean all six contact points on both the battery and dock with a dry cloth, reseat the battery, and confirm the dock accepts it before transmitting again.