Motorola R2 Replacement Battery PMNN4598A 7.4V 3350mAh

Motorola R2 — 7.4V Li-ion Replacement Battery (PMNN4598A / PMNN4600A)

This is a 7.4V, 3350mAh lithium-ion battery for the Motorola R2 portable two-way radio. It replaces OEM part numbers PMNN4598A and PMNN4600A. The R2 is widely used in security, dispatch, and field operations where battery failure means loss of communication.

• R2 platform fit: The R2 runs a 7.4V nominal voltage rail with a multi-pin BMS handshake at the contact strip. Both PMNN4598A and PMNN4600A share this rail and connector layout, which is why a single cell pack covers both OEM references without modification.
• Bench tested on actual hardware: We ran this pack through the R2 charger dock and monitored the BMS negotiation cycle. The pack accepted charge without fault, passed the overcurrent threshold check during simulated PTT draw, and held voltage within expected range across the full charge cycle.
• First insertion on the R2 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 requires a clean contact cycle to complete the BMS handshake before charging begins — this is not a defective pack.

Why the R2 cuts out mid-transmission on a new battery

A new lithium-ion cell ships at storage voltage — typically around 3.6–3.7V per cell, not full charge. When the R2 transmits, PTT current draw spikes sharply. If the pack is not fully charged before first use, the BMS may read that spike as an overcurrent event and cut output momentarily. This is a BMS protection response, not a hardware fault. Fully charge the pack to 8.4V before the first shift and the cutouts stop.

R2 bar indicator showing one fewer bar than expected after swap

The R2 uses a voltage-threshold bar indicator, not a fuel gauge chip. Each bar corresponds to a voltage band, and a new pack at storage voltage will show one or two bars short of full. This is accurate — the cell is not at full charge yet, and the radio is reading voltage correctly. Put the pack on the dock for a full charge cycle. Once the pack reaches 8.4V, the bar indicator will reflect full charge on the next power cycle.