Motorola MagOne RTN4000A Replacement Battery 10.8V 1200mAh

Motorola MagOne RTN4000A — 10.8V Ni-MH Replacement Battery

This is a 10.8V, 1200mAh Ni-MH replacement battery for the Motorola MagOne RTN4000A two-way radio. It slots directly into the radio's battery bay and connects to the same dock contacts as the original pack. Voltage and capacity match the OEM specification exactly.

• MagOne RTN4000A platform fit: The RTN4000A uses a 10.8V Ni-MH pack with a specific contact layout and BMS handshake sequence. This battery matches that voltage rail and contact geometry, so the charger dock and radio firmware both recognise it as a valid pack on first insertion.
• Bench tested on actual hardware: We cycled this pack through transmit loads that mirror PTT-heavy commercial use. The BMS held the voltage rail steady through repeated transmit current spikes and did not trip into protection mode during any test cycle.
• First-insertion contact check on the RTN4000A dock: If the charger dock shows a fault LED on first insertion, remove the battery, wipe the gold contact strip with a dry cloth, and reseat firmly. The MagOne platform requires a clean contact cycle to complete the BMS handshake before charging begins — this is not a faulty cell.

Why the RTN4000A cuts out mid-transmission on a new battery

When PTT is pressed, the radio draws a sharp transmit current spike that can exceed 1A in under a millisecond. A new Ni-MH cell sitting at storage voltage — typically around 10.2–10.4V — can trigger the BMS overcurrent threshold before the cell has warmed up through a few charge cycles. The radio interprets that brief voltage drop as a low-battery condition and interrupts transmission. Running two or three full charge-discharge cycles brings the cells to operating voltage and resolves the cutout.

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

The RTN4000A reads battery level through fixed voltage thresholds, not a fuel gauge chip. A new pack shipped at storage voltage — around 10.2V — sits below the threshold the radio uses to display a full bar reading. This is not a capacity fault. Charge the battery fully before first use and the indicator will reflect actual cell voltage, typically stepping up to the highest bar at or above 10.8V.