Nokia THR9 Replacement Battery 3.7V 2300mAh Li-ion

Nokia THR9 / THR9i / THR9+ — 3.7V Li-ion Replacement Battery

This is a 3.7V, 2300mAh Li-ion battery for the Nokia THR9, THR9i, and THR9+ professional portable two-way radios. All three variants share the same battery bay geometry and contact arrangement, so one pack covers the full family. Capacity figures come from the product data, not third-party estimates.

• THR9 family compatibility: The THR9, THR9i, and THR9+ run the same 3.7V battery rail and use an identical contact strip layout. No mechanical modification is needed to swap between variants — the BMS handshake protocol is consistent across all three.
• Bench tested on actual hardware: We cycled this pack through transmit and standby loads on the THR9 platform. The BMS held stable across repeated PTT events without triggering overcurrent cutoff, and the contact interface seated cleanly in the battery bay.
• Contact strip care on first insertion: If the Nokia charging dock shows a fault LED when you first insert this pack, remove it, wipe the gold contact strip with a dry cloth, and reseat firmly. The dock requires a clean contact surface to complete the BMS handshake before it will begin charging.

Why the THR9 drops to reduced TX power mid-shift on a new battery

The THR9 manages transmit power based on real-time voltage readings from the battery. A new cell shipped at storage voltage — typically around 3.6–3.7V — can sag under the sustained current draw of RF output, pushing the radio's protection circuit to throttle transmission power. This is not a fault with the pack. Running two or three full charge cycles through the dock normalises cell impedance and raises the resting voltage enough to sustain full TX power throughout a shift.

THR9 bar indicator showing one fewer bar than expected on a new pack

The THR9 uses voltage-threshold bar indicators, not a fuel gauge chip. A new pack at storage voltage reads lower than a fully charged cell, so the radio displays one fewer bar even though the battery is not depleted. This is a voltage reading, not a capacity fault. Charge the pack fully in the Nokia dock — once the cell reaches its nominal 4.2V peak, the bar display will reflect the correct charge state.