HYT TB-66 Replacement Battery 7.2V 1100mAh Ni-MH

HYT TC-2100H / TC-2110 / TC-2108 — 7.2V Ni-MH Replacement Battery (TB-66)

This is a 7.2V 1100mAh Ni-MH replacement battery for the HYT TC-2100H, TC-2110, and TC-2108 portable two-way radios. It replaces OEM part numbers TB-66, BH0901, and BL1202. Voltage, connector, and BMS handshake all match the original HYT specification.

• TC-2100H, TC-2110, and TC-2108 fitment: All three models share the same battery bay geometry, contact rail spacing, and 7.2V nominal voltage requirement. A single BMS firmware threshold governs the charge acceptance window across the platform, so one battery pack covers the full family.
• Bench tested on actual hardware: We cycled this pack through a full charge-discharge sequence on the TC-2100H. The BMS accepted the charge handshake without fault, held voltage above the low-battery cutoff through sustained PTT cycles, and recovered correctly from a simulated storage-depth discharge.
• First insertion into a HYT dock: If the charger LED flashes fault on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The HYT dock requires a clean contact cycle to complete the BMS handshake before it begins the charge sequence.

Why the TC-2100H cuts out mid-transmission on a freshly inserted battery

Pressing PTT on the TC-2100H draws a short transmit-current spike that can trip the BMS overcurrent threshold if the pack was stored at low voltage for an extended period. The BMS interprets the spike as an unsafe load event and shuts the output rail. This is not a faulty battery — it is the protection circuit responding to a cell that has not yet recovered from storage voltage. Seat the pack in the charger dock first, let it complete at least one full charge cycle, and the BMS will clear the overcurrent flag before you key up.

Bar indicator showing one fewer bar than expected after fitting this pack

The TC-2100H uses a simple voltage-threshold bar indicator — each bar corresponds to a fixed voltage band, not a capacity percentage. A new Ni-MH cell ships at storage voltage, typically around 6.8–7.0V, which sits one threshold below a fully charged pack at approximately 8.4V. The radio reads that lower open-circuit voltage and displays one bar fewer than you expect. Charge the pack fully in the dock before first use and the indicator will step up to reflect the correct resting voltage.