About this replacement
ZTE PH500 / PH520 — 7.4V Li-ion Replacement Battery (AB500 / AB600)
This 7.4V, 1800mAh Li-ion pack replaces the original battery in the ZTE PH500 and PH520 portable two-way radios. It fits both models and matches OEM part numbers AB500 and AB600. Capacity is 1800mAh (13.32Wh) — identical to the factory specification.
- PH500 and PH520 platform fit: Both models share the same battery bay geometry, connector pinout, and BMS handshake protocol. One pack covers both radios without any adapter or modification.
- Bench tested on actual hardware: We cycled this pack through transmit and receive loads on the bench. The BMS held stable across repeated PTT surges and tripped correctly at the low-voltage cutoff threshold — no nuisance shutdowns during sustained TX.
- First insertion into the charger dock: If the dock LED shows a fault on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The ZTE charger requires a clean contact cycle to register the new pack's BMS before charging begins.
Why the PH500 cuts out mid-transmission on a new AB500 pack
A PTT press pulls a sharp current spike — often two to three times the standby draw — to power the RF output stage. If the replacement pack ships at storage voltage (typically around 3.7V per cell), the BMS may interpret that surge as an overcurrent event and trip the protection circuit. The radio goes silent instantly. This is not a faulty pack — it is the BMS doing its job on a cell that has not yet been conditioned. Seat the pack in the charger, let it reach full charge, then retry transmission.
Bar indicator shows one fewer bar than expected after fitting a new pack
The PH500 and PH520 read battery level using voltage thresholds — the radio checks terminal voltage and maps it to a bar count. A new cell fresh from storage sits below the top threshold, so the indicator shows one bar short of full even though the pack is not discharged. This is a voltage reading issue, not a capacity problem. Charge the pack fully until the dock LED goes green, then power the radio on — the bar indicator will read correctly at that point.