Motorola GP2000 Replacement Battery PMNN4046A 7.5V 2500mAh

Motorola GP2000 / GP2100 Series — 7.5V Li-ion Replacement Battery (PMNN4046A)

This 7.5V 2500mAh Li-ion battery replaces the PMNN4046A pack in Motorola GP2000, GP2000s, GP2100, and SP66 two-way radios. It fits the same connector and BMS handshake point as the OEM unit. Capacity is drawn from product data — 2500mAh / 18.75Wh.

• GP2000 / GP2100 platform fit: These models share a common 7.5V cell stack, identical connector housing, and the same BMS communication protocol — so one pack covers the full series without modification.
• Bench tested on actual hardware: We ran this pack through a full charge cycle and PTT transmit load on a GP2000 body. The BMS held the voltage rail steady through repeated transmit bursts and released the protection circuit cleanly at end-of-discharge.
• First insertion into the charger dock: If the dock shows a fault LED on first insertion, remove the battery, wipe the gold contact strip with a dry cloth, and reseat firmly. The GP2000 charger platform requires a clean contact cycle to accept the new BMS handshake before charging begins.

Why the GP2000 cuts out mid-transmission on a new PMNN4046A

A new Li-ion pack ships at storage voltage — typically 3.6–3.7V per cell, not full charge. When PTT is pressed, the radio draws a sharp current spike to power the RF output stage. At storage voltage, that spike can drag the cell voltage below the BMS undervoltage threshold momentarily, triggering a protection cutoff. The radio goes silent not because the battery is faulty, but because the pack hasn't been fully charged before use. A complete charge cycle before the first shift eliminates this behaviour.

Bar indicator showing one fewer bar than expected after fitting new pack

The GP2000 uses a simple voltage-threshold bar indicator — it reads battery state by measuring terminal voltage, not cell chemistry history. A new pack at storage voltage sits below the threshold for a full bar display, so the radio shows one bar even though the cell is not depleted. This is not a capacity fault. Charge the battery fully; once terminal voltage reaches approximately 8.3–8.4V, the indicator will step up to reflect the actual charge state.