B-81I Inrico BS-81G Replacement Battery 3.85V 5900mAh

Inrico BS-81G — 3.85V Li-ion Replacement Battery (B-81I)

This 3.85V, 5900mAh Li-ion battery replaces the B-81I pack in the Inrico BS-81G two-way radio. It fits the BS-81G directly and matches the original voltage rail and connector profile. The 22.72Wh capacity supports full-shift use by security, events, and emergency response crews.

• BS-81G platform fit: The BS-81G runs a single-cell 3.85V architecture. This pack matches that rail exactly. The BMS communicates with the radio's charge management circuit using the same handshake protocol as the original B-81I, so the radio accepts the pack without throwing a fault state.
• Bench tested on actual hardware: We cycled this pack through transmit and standby loads on the BS-81G platform. The BMS handled PTT-triggered current spikes without tripping into overcurrent lockout. Charge termination was clean at full voltage with no false-positive fault signals from the dock.
• First insertion on the BS-81G charger dock: If the dock LED shows a fault on first insertion, remove the pack and wipe the contact strip with a dry cloth before reseating. The BS-81G charger checks contact resistance before initiating the charge cycle — a single residue layer on the contacts is enough to trigger a rejection flag.

BS-81G bar indicator showing one fewer bar than expected on a new B-81I pack

The BS-81G uses voltage thresholds to calculate the bar indicator — it does not read capacity directly. A new pack ships at storage voltage, typically around 3.6–3.7V, which sits below the top threshold for a full-bar reading. The radio correctly interprets this as not-full, because at that voltage it is not full. Run one complete charge cycle through the dock and the indicator will reflect the actual resting voltage of a fully charged cell, which sits at 4.2V for this chemistry.

BS-81G drops to reduced TX power mid-shift on a charged pack

Sustained RF output draws significantly more current than standby, and if the pack's internal impedance is elevated, voltage sags under that load. The BS-81G responds to a voltage sag by stepping down transmit power to protect the circuit. This is not a faulty battery — it is the radio managing a real voltage drop. Check resting voltage after the radio cools; if it recovers above 3.7V, impedance is the cause. A full discharge and recharge cycle can reduce impedance slightly on a new pack in its first few cycles.