About this replacement
Inrico T740 — 3.7V Li-ion Replacement Battery (B-52H)
This is a 3.7V 5300mAh lithium-ion replacement battery for the Inrico T740 portable digital two-way radio. It carries OEM part number B-52H and fits the T740 directly. The T740 is used in security, logistics, and emergency services — environments where a battery that won't hold charge is a liability.
- T740 platform fit: The T740 uses a single-cell Li-ion pack at 3.7V with a specific connector and BMS handshake. This battery matches that voltage rail, connector format, and BMS communication requirement so the radio recognises it and charges normally.
- Bench tested on actual hardware: We ran the B-52H on a T740 dock and monitored BMS response across a full charge cycle. The protection circuit handled transmit-current spikes without tripping, and the pack accepted charge from the standard dock without a fault LED.
- First insertion on the T740 dock: If the dock shows a fault LED on first insertion, remove the battery, wipe the gold contact strip with a dry cloth, and reseat firmly. The T740 platform requires a clean contact cycle before the dock accepts the new BMS handshake and begins charging.
Why the T740 cuts out mid-transmission on a new B-52H battery
The T740's transmit circuit draws a sharp current spike the moment PTT is pressed. A new cell shipped at storage voltage — typically around 3.6V to 3.7V — sits close to the BMS undervoltage threshold under that load. If the BMS reads a momentary voltage dip below its cutoff, it interrupts power to protect the cell. This is not a faulty battery. Run one full charge cycle on the dock before heavy PTT use and the issue resolves.
T740 bar indicator showing one fewer bar than expected after fitting new B-52H
The T740 reads battery level using voltage thresholds only — it has no capacity-tracking circuit. A new pack at storage voltage will read one bar lower than a fully charged pack until the first full charge completes. This is normal and not a sign the battery is undersized or faulty. Charge the pack fully on the T740 dock and the bar indicator will reflect the correct level at 4.2V.