About this replacement
Motorola XPR3300 / XPR3550 Series — 7.4V Li-ion Replacement Battery (PMNN4490)
This is a 7.4V, 2450mAh lithium-ion battery for the Motorola XPR3300, XPR3300e, XPR3550, and XPR3550e two-way radios. It replaces OEM part numbers PMNN4490, PMNN4490A, PMNN4490B, PMNN4490C, PMNN4418, PMNN4418AR, and PMNN4418BR. The battery slots into the standard battery bay and connects via the same multi-pin contact strip as the original pack.
- XPR3300 / XPR3550 platform fit: These models share a common 7.4V voltage rail, identical multi-pin connector layout, and the same BMS handshake protocol. One battery SKU covers both the standard and 'e' variants because the dock and radio firmware treat them identically.
- Bench tested on actual hardware: We ran this pack in an XPR3300e dock and cycled it through full transmit loads. The BMS held stable across sustained PTT events with no overcurrent trip, and the dock advanced from charge to ready without fault codes.
- First insertion on a Motorola impres-style dock: If the dock LED stays red or blinks fault after the first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and firmly reseat it. The XPR platform requires a clean contact cycle to complete the initial BMS handshake before charging begins.
Why the XPR3300 cuts out mid-transmission on a new battery
A new cell ships at storage voltage — typically around 3.7V per cell, well below the 4.2V full-charge peak. When you press PTT, transmit current spikes hard and fast. If the pack hasn't completed at least one full charge cycle, the BMS can read that current spike as an overcurrent event and trip the protection circuit, killing the transmission. Charge the pack fully in the dock before the first field use. After one complete charge cycle, the BMS recalibrates its overcurrent threshold against the actual cell capacity and the mid-transmission dropout stops.
Bar indicator showing one fewer bar than expected on a fresh pack
The XPR3300 uses a voltage-threshold bar system — each bar represents a voltage band, not a fuel gauge calculation. A new pack at storage voltage sits in a lower band than a freshly charged one, so the radio displays fewer bars even though the battery is not faulty. This is not a capacity or hardware problem. Charge the pack fully and the indicator will step up to the correct reading once cell voltage clears the 7.9V threshold.