About this replacement
Motorola GP900 / HT1000 Series — 7.5V Ni-MH Replacement Battery (NTN7143)
This is a 7.5V, 1500mAh nickel-metal hydride battery for Motorola portable land mobile radios including the GP900, GP1200, HT1000, and HT6000. It replaces OEM part numbers NTN7143, NTN7144, and their variants. The pack slots into the same housing as the original and connects to the same BMS handshake points in the charger dock.
- GP900, GP1200, HT1000, HT6000 platform: These models share the same 7.5V three-cell Ni-MH rail, identical connector pinout, and the same dock communication protocol — so one pack covers the whole family without any adapter or firmware flag.
- Bench tested on actual hardware: We cycled this pack through full charge and transmit-load discharge on the GP900 platform. The BMS held stable under repeated PTT draw spikes and the dock accepted the pack without fault LED on a clean contact seat.
- First insertion into the dock: If the dock shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The Motorola dock requires a clean contact cycle to register the new pack's BMS handshake before charging will begin.
Why the GP900 cuts out mid-transmission on a new NTN7143 pack
A new Ni-MH pack ships at storage voltage — typically 6.8–7.0V across three cells. When PTT is pressed, the transmitter pulls a sharp current spike of 1.5–2A or more. If the cells haven't been through a full charge cycle first, that spike can drag terminal voltage below the radio's undervoltage cutoff, killing the transmission. The BMS interprets this as an overcurrent event and opens the output gate. Run one full charge before taking the radio into the field.
Bar indicator showing one fewer bar than expected on a freshly charged pack
The GP900 uses a voltage-threshold bar indicator, not a fuel gauge chip. A new Ni-MH cell at full charge reads slightly lower than a broken-in cell because the voltage curve hasn't been conditioned yet. After two or three full charge-discharge cycles, cell voltage at full charge rises to its rated peak and the indicator catches up. If the pack still reads low after three cycles, check terminal voltage with a meter — a healthy 7.5V Ni-MH pack fully charged should read 8.4–8.7V at rest.