Motorola GP2000 Two-Way Radio Replacement Battery PMNN4046A 7.5V

Motorola GP2000 / GP2100 / SP66 Series — 7.5V Ni-MH Replacement Battery (PMNN4046A)

This 7.5V, 1800mAh Ni-MH battery replaces the PMNN4046A pack in the Motorola GP2000, GP2000s, GP2100, and SP66 two-way radios. These are portable land mobile radios used in public safety, industrial, and business communications. It fits the same connector and battery bay as the original pack, with no hardware modification required.

• GP2000 and GP2100 battery bay compatibility: These models share the same physical battery bay, contact rail, and 7.5V BMS handshake threshold. A pack that clears the BMS on a GP2000 will clear it on a GP2100 and SP66 without modification.
• Bench tested on actual hardware: We cycled this pack through full charge and transmit-load discharge on a GP2000 chassis. The BMS held the voltage rail stable through repeated PTT press sequences and accepted the Motorola dock charge cycle without fault flags.
• First-insertion contact check on the GP2000 dock: If the charger shows a fault LED on the first seating, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The GP2000 dock requires a clean contact cycle to complete the BMS handshake before charging begins.

Why a new PMNN4046A pack reads fewer bars than expected on the GP2000

Ni-MH cells ship at storage voltage — typically 1.1–1.2V per cell — not at full charge. The GP2000 uses a simple voltage-threshold bar indicator, so a new pack at storage voltage will display one or two fewer bars than a fully charged pack. This is not a capacity or cell fault. Run the pack through one full charge cycle in the Motorola dock before judging bar level. After a complete charge, the indicator will reflect actual cell state.

Radio drops to reduced TX power partway through a shift on a fresh pack

This happens when sustained RF output pulls the cell voltage below the GP2000's TX power threshold — typically around 6.8V under load. Ni-MH voltage sag is steeper than Li-ion under high current draw, and new cells that haven't been conditioned can sag faster in the first few cycles. The radio steps down TX power to protect the RF stage, not because the pack is faulty. Cycle the pack two to three times with full charge and moderate use, and measure resting voltage after charge — a healthy PMNN4046A should read at or above 7.5V at rest.