About this replacement
Motorola GP900 / HT1000 Series — 7.5V Ni-MH 2500mAh Replacement Battery (NTN7143)
This is a 7.5V Ni-MH battery rated at 2500mAh (18.75Wh), built to fit the Motorola GP900, GP1200, HT1000, HT6000, and compatible variants. It replaces OEM part numbers NTN7143, NTN7144, NTN7143CR, NTN7144CR, and several related suffixes. Connector orientation, casing dimensions (153 × 59 × 20mm), and BMS handshake match the original dock and radio body.
- GP900 / HT1000 platform fit: These models share the same battery bay geometry, 7.5V power rail, and contact pinout. One battery SKU covers the full range without adapter modifications or connector rework.
- Bench tested on actual hardware: We cycled this pack through three full charge-discharge sequences on a GP900 body. The BMS accepted charger handshake on first dock insertion, held voltage above 6.9V through sustained TX load, and showed no thermal trip during repeated PTT cycling.
- First-insertion contact reset on the GP900 dock: If the dock LED shows a fault on first insertion, remove the pack and wipe the gold contact strip with a dry cloth before reseating. The GP900 charging dock requires a clean contact surface to complete the BMS handshake — this is not a faulty pack, it is a platform behaviour common across the Motorola professional radio line.
Why the GP900 cuts out mid-transmission on a freshly inserted battery
When PTT is pressed on a GP900, transmit current spikes sharply — often 1.5A to 2A above standby draw. A new Ni-MH pack shipped at storage voltage (typically 6.0–6.5V) may sit just above the radio's undervoltage cutoff threshold. That spike then pulls the pack below the cutoff, and the radio drops TX without warning. The fix is a full charge cycle before field deployment — not a workaround, just letting the cells reach operating voltage. After one complete charge, the pack holds the voltage rail through sustained PTT use without tripping cutoff.
Bar indicator showing one fewer bar than expected after a full charge
The GP900 uses a simple voltage-threshold bar display — each bar corresponds to a voltage band, not a percentage calculation. Fresh Ni-MH cells can take two to three full charge-discharge cycles before they reach peak resting voltage, so the indicator may read one bar low early on. This is not a capacity fault. Run the radio down to the low-battery warning, charge fully, and repeat once more — resting voltage stabilises and the bar reading corrects to match actual charge state.