About this replacement
Kenwood TK-3140 / TK-2140 Series — 7.2V Ni-MH Replacement Battery (KNB-24L)
This is a 7.2V, 2100mAh Ni-MH battery for the Kenwood TK-3140, TK-2140, TK-2160, TK-2170, and compatible models. It replaces OEM part numbers KNB-24L, KNB-25A, KNB-26, KNB-26N, KNB-56N, KNB-55L, KNB-35L, and KNB-57L. The pack slots directly into the standard battery bay on these Kenwood handheld transceivers.
- TK-2140 / TK-2160 / TK-2170 / TK-3140 compatibility: These models share the same 7.2V voltage rail, contact layout, and BMS handshake protocol — which is why one battery family covers the full lineup. The connector footprint and latch geometry are identical across this generation of Kenwood portables.
- Bench tested on actual hardware: We ran this pack through charge and transmit cycles on a TK-3140 dock. The BMS negotiated cleanly on first insertion, held voltage through repeated PTT bursts, and the charger advanced to trickle without a fault LED.
- First insertion on a Kenwood dock: If the dock shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. Kenwood chargers require a clean contact cycle to complete the BMS handshake before charging begins — this is not a defective battery.
Why the TK-3140 cuts out mid-transmission on a new Ni-MH pack
Ni-MH cells ship at a reduced storage voltage — typically 30–50% of full charge. When the radio keys up and demands transmit current, the pack voltage sags below the BMS cutoff threshold before the cells have completed a full conditioning cycle. The radio interprets this as a low-battery event and drops TX. One or two full charge-discharge cycles through the Kenwood dock brings the cells to rated capacity and eliminates the sag. After conditioning, the pack sustains the transmit current draw without tripping the cutoff.
Bar indicator showing one fewer bar than expected on a fresh KNB-24L
Kenwood handhelds use a voltage-threshold bar indicator — each bar corresponds to a specific resting voltage band. A new Ni-MH pack at storage voltage reads lower than a fully charged one, so the radio displays one or two fewer bars even though the pack is not faulty. Charge the battery fully in the Kenwood dock until the charge LED goes green. After a complete charge cycle the resting voltage will sit above 8.4V and the indicator will reflect the correct state.