About this replacement
Motorola MTP700 / MTP750 — 7.5V Li-ion Replacement Battery (PMNN4047)
This is a 7.5V 1800mAh Li-ion battery for the Motorola MTP700 and MTP750 portable two-way radios. It replaces OEM part numbers PMNN4047, FTN6573, FTN6574, PMN4047BR, and PMR4047. If your original pack is no longer holding a charge between shifts, this is the direct swap.
- MTP700 and MTP750 platform fit: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. One pack covers both radios without any hardware change.
- Bench tested on actual hardware: We ran this pack through the MTP700 charge dock and confirmed BMS initialisation, full charge acceptance, and correct voltage output across the contact strip. The protection circuit responded correctly to charge termination at capacity.
- First insertion into the dock: If the charger shows a fault LED on first seat, pull the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The MTP platform requires a clean contact cycle before it accepts the BMS handshake and begins charging.
MTP700 cutting out or dropping TX power mid-transmission on a new pack
During PTT, the MTP700 draws a sharp current spike to drive the RF output stage. If the battery's BMS detects this spike as an overcurrent event, it interrupts the load for a fraction of a second — long enough to drop the transmission. A new pack at storage voltage (typically around 3.7–3.8V per cell) is more vulnerable to this trip point than a fully charged pack. Charge the battery to full before the first shift and the BMS trip threshold will sit well above the transmit current spike.
Bar indicator showing one fewer bar than expected after fitting this pack
The MTP700 reads battery level using voltage thresholds, not a chip that tracks charge history. A new Li-ion cell ships at storage voltage, not full charge, so the radio registers fewer bars even though the pack is not faulty. Place the pack in the charger dock for a full charge cycle. Once the cell voltage reaches its top-of-charge level near 8.4V across the pack, the indicator will read correctly.