About this replacement
HYT TC-500 / TB75 Series — 6V Ni-MH Replacement Battery (BH1104)
This is a 6V, 1200mAh Ni-MH replacement battery for the HYT TC-500, TC-500-U1, TC-500-V1, and TB75 two-way radios. It replaces OEM part numbers BH1104, BH1106, BH1301, and BH1302. Physical dimensions match the original pack at 99.34 × 53.72 × 32.84mm, so the battery seats correctly in the radio chassis without modification.
- TC-500 and TB75 platform fit: Both the TC-500 variants and the TB75 share the same battery bay format, contact pin layout, and 6V supply rail. A single pack covers all four model designations without adapter plates or pin swaps.
- Bench tested on actual hardware: We cycled this pack through charge-discharge on a TC-500 unit. The BMS accepted the dock handshake cleanly on the first insertion, and transmit current draw at PTT press registered within the expected range for this voltage class with no cutoff event recorded.
- Contact strip prep on first install: If the charger dock shows a fault LED on first insertion, remove the battery, wipe the gold contact strip with a dry cloth, and reseat firmly. The TC-500 dock requires a clean contact cycle to accept the BMS handshake before the charge cycle can begin.
Why the TC-500 cuts out mid-transmission on a new Ni-MH pack
Ni-MH cells ship at storage voltage — typically 1.1–1.2V per cell, which puts a 6V five-cell pack around 5.5–5.8V on arrival. The TC-500's BMS monitors voltage under PTT load, and if the pack hasn't been charged first, the transmit current spike can pull voltage below the cutoff threshold, dropping the transmission. This is not a faulty battery. Run a full charge cycle before the first use and the pack will hold the voltage rail through sustained PTT without dropping out.
TC-500 bar indicator showing one fewer bar than expected after swap
The TC-500 reads battery state through simple voltage-threshold steps — each bar corresponds to a voltage window, not a percentage from a fuel gauge chip. A freshly charged new pack sitting at storage voltage rather than full-charge voltage will land in a lower threshold band and display one fewer bar than the original worn pack did at "full." Charge the new pack completely in the dock, then power cycle the radio. At full charge voltage the bar indicator will reflect the correct state.