About this replacement
Harris P5300 / P5400 Series — 7.4V Li-ion Replacement Battery (BT-023406-003)
This 7.4V Li-ion pack replaces the OEM battery in the Harris P5300, P5350, P5370, P5400, and compatible variants. It carries 4100mAh (30.34Wh) of capacity in the same physical shell the radio expects. Fits the multi-pin connector and BMS handshake protocol these radios require before they power on.
- P5300 / P5400 platform compatibility: These models share a common battery bay, connector pinout, and BMS communication protocol across the series. A pack that clears the handshake on a P5300 will clear it identically on a P5370 or P5400 — same voltage rail, same pin layout, same acceptance threshold.
- Bench tested on actual hardware: We seated this pack in a P5400 dock and monitored the BMS initialisation sequence. The pack negotiated the handshake without fault, accepted charge from the first cycle, and held voltage within spec through sustained PTT draw.
- First-insertion contact check: Harris P-series docks read the battery contacts during the first 90 seconds of insertion. If the dock LED flashes a fault immediately, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly — one debris particle on that strip is enough to break the handshake before charging starts.
Why the P5300 cuts out mid-transmission on a new battery
Harris P-series radios draw a spike of current the moment PTT is pressed — transmit current can exceed 2A in under 50 milliseconds. The BMS in a new pack ships at storage voltage, typically around 3.7–3.8V per cell. At that voltage, the BMS overcurrent threshold is tighter than it is at a full charge. One hard PTT press at storage voltage can trip the BMS and cut transmission. Cycle the pack to full charge before putting the radio into operational use — the cutout problem disappears once cells are above 4.0V per cell.
Bar indicator showing fewer bars than expected after fitting this pack
The P5300 and P5400 use a voltage-threshold bar indicator — each bar corresponds to a voltage band, not a percentage. A new pack at storage voltage sits in the middle band, so the radio shows two or three bars rather than full. This is not a capacity fault. Charge the pack fully in the dock until the LED goes solid green, then power on the radio — the indicator will reflect actual resting voltage, which at full charge puts the needle in the top band.