About this replacement
Motorola R2 — 7.4V Li-ion Replacement Battery (PMNN4598A / PMNN4600A)
This is a 7.4V, 3300mAh Li-ion replacement battery for the Motorola R2 two-way radio. It replaces OEM part numbers PMNN4598A and PMNN4600A. It fits the R2 platform used in security, dispatch, and field operations where continuous shift coverage is non-negotiable.
- R2 platform fit: The R2 runs a 7.4V nominal rail with a specific BMS handshake protocol at the contact interface. Both PMNN4598A and PMNN4600A share the same connector pinout and voltage threshold, which is why this single pack covers both OEM references.
- Bench tested on actual hardware: We cycled this pack on the R2 platform and logged BMS response across transmit loads. The protection circuit held within spec during sustained PTT events, and the dock accepted the pack without a fault flag after a clean contact seating.
- First insertion on the R2 charger dock: If the dock LED flashes amber or shows a fault on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The R2 dock runs a BMS handshake check before it begins the charge cycle — a trace of oxidation or dust on the contacts is enough to fail that check.
Why the R2 cuts out mid-transmission on a new battery
During PTT, the R2 draws a short but sharp current spike as the RF stage powers up. If the BMS interprets this spike as an overcurrent event, it trips the protection circuit and cuts the radio off — even on a fresh pack. This is not a faulty battery. It happens when the pack is at storage voltage rather than a full charge, because internal resistance is higher at lower states of charge, which amplifies the voltage sag under transmit load. Charge the pack fully before the first operational shift and the BMS will handle normal PTT loads without tripping.
R2 bar indicator showing one fewer bar than expected on a new pack
The R2 uses voltage-threshold bar indicators — each bar represents a voltage band, not a percentage from a fuel gauge chip. Replacement packs ship at storage voltage, typically around 3.7–3.8V per cell, which sits below the threshold for a full bar reading. This is normal. Run the pack through a full charge cycle on the R2 dock first. After a complete charge, the terminal voltage will sit at or above 8.2V and the bar indicator will reflect the correct state.