Motorola CP250 HNN8133C Replacement Battery 7.4V 3600mAh

Motorola CP250 / GP300 Series — 7.4V Li-ion Replacement Battery (HNN8133C)

This 7.4V, 3600mAh Li-ion pack replaces the OEM battery on Motorola CP250, CP450, CP450LS, GP300, and a range of compatible portable two-way radios. It matches the original voltage rail and physical footprint so it seats correctly in the radio body and standard Motorola drop-in charger docks. Capacity is 3600mAh (26.64Wh) — drawn from product data, not estimated.

• CP250 / CP450 / GP300 platform fit: These models share a common 7.4V power rail, identical battery cavity dimensions, and the same BMS handshake protocol. One cell format covers the full group — no adapters, no modified contacts.
• Bench tested on actual hardware: We cycled this pack through transmit load pulls on the CP250 platform. The BMS held steady under sustained PTT draw and tripped cleanly at the correct undervoltage threshold without latching.
• First insertion into the charger dock: If the dock LED flashes fault on first seat, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The Motorola dock runs a BMS handshake before accepting charge — a single clean contact cycle clears this in most cases.

Why the CP250 cuts out mid-transmission on a freshly inserted pack

New Li-ion cells ship at storage voltage — typically 3.7V per cell, putting a two-cell pack around 7.4V at rest. Under a PTT transmit spike, the radio draws a surge of current that briefly collapses the terminal voltage below the BMS cutoff threshold. The BMS interprets this as a depleted or fault condition and interrupts power to protect the cells. This is not a defective battery — it is normal BMS behaviour on a cold pack at storage charge. Run the pack through one full charge cycle before use and the cutoff issue stops.

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

Motorola CP-series radios read battery level from voltage thresholds at the power rail — not a fuel gauge chip. A new pack at storage voltage sits at the boundary between the second and third bar threshold, so the display shows one bar fewer than you expect. This is a storage-voltage reading, not a capacity fault. Charge the pack fully — the radio will read the correct bar level once the pack reaches its rated 8.4V charged voltage.