PUXING PB-72L Compatible Battery 7.4V 1200mAh Li-ion

PUXING PX-888K / PX-328 Series — 7.4V Li-ion Replacement Battery (PB-72L)

This is a 7.4V 1200mAh Li-ion pack built to the PB-72L specification. It fits the PUXING PX-888K, PX-UV973, PX-777, and PX-328, plus four additional models in the same family. Voltage and connector format match the original, so it seats and charges through the standard dock without modification.

• PX-888K / PX-328 platform fit: These models share a common 7.4V rail, the same latch geometry, and the same contact strip pitch. One pack covers the entire lineup because the BMS handshake threshold is identical across all variants in this family.
• Bench tested on actual hardware: We cycled this pack through transmit load on a PX-888K body and monitored BMS behaviour under the PTT current spike. The protection circuit held cutoff at the correct threshold and did not trip during sustained keying.
• First-insertion contact check: If the charger shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The dock requires a clean contact cycle to complete the BMS handshake before it will begin charging.

Why the PX-888K cuts out mid-transmission on a new PB-72L pack

New cells ship at storage voltage — typically around 3.7V per cell, giving roughly 7.4V at the pack terminals. Under the PTT current spike, that storage-voltage starting point can push the instantaneous pack voltage below the BMS low-voltage cutoff, triggering a momentary trip. The radio cuts out, then resets within a second. This is not a fault with the pack — it is the BMS doing its job on a cell that has not yet completed its first full charge cycle. Run a full charge before first use and the cutoff threshold will no longer be at risk during transmit.

Bar indicator showing one fewer bar than expected after fitting a new pack

The PX-888K uses a simple voltage-threshold bar display — each bar corresponds to a voltage window, not a fuel gauge reading. A new pack at storage voltage sits in the lower window and displays fewer bars even though capacity is not depleted. Charge the pack fully to approximately 8.4V and the bar indicator will move to the correct level. If it still reads low after a full charge, check that the contact strip is making clean contact with the dock — a resistive connection causes a voltage drop that pulls the reading down.