Kenwood KNB-24L TK-3140 Compatible Battery 7.2V

Kenwood TK-3140 / TK-2140 Series — 7.2V Ni-MH Replacement Battery (KNB-24L)

This is a 7.2V, 1300mAh Ni-MH replacement battery for the Kenwood TK-3140, TK-2140, TK-2160, TK-2170, and eleven additional TK-series portable radios. It replaces OEM part numbers KNB-24L, KNB-25A, KNB-26, KNB-26N, KNB-56N, KNB-55L, KNB-35L, and KNB-57L. The cell stack matches the original voltage rail and connector pinout for these radios.

• TK-2100 / TK-3100 platform compatibility: These Kenwood portables share a common battery bay dimension, seven-pin contact strip, and 7.2V BMS handshake across the TK-2140, TK-2160, TK-2170, and TK-3140 lines — which is why a single pack covers the full group. The connector latch and contact geometry are identical across all listed models.
• Bench tested on actual hardware: We ran this pack on a TK-3140 and cycled it through transmit loads at full RF output. The BMS held voltage above the radio's low-battery threshold across repeated PTT bursts and did not trip the overcurrent cutoff during sustained TX draws.
• Contact strip care on first dock insertion: If the Kenwood charger shows a fault LED on first insertion, remove the pack, wipe the gold contact strip with a dry cloth, and reseat firmly. The charger dock needs a clean contact cycle to complete the BMS handshake before it will begin charging — a light film of packaging residue on the contacts is enough to block it.

Why the TK-3140 cuts out mid-transmission on a new battery

When PTT is pressed, the TK-3140 pulls a sharp current spike to power the RF amplifier — this is the highest draw event the battery sees. On a new Ni-MH pack at storage voltage, that spike can briefly drop the cell voltage below the BMS's overcurrent threshold, triggering a protective cutoff before the radio fully transmits. The fix is to complete two or three full charge cycles so the cells reach their rated capacity and internal resistance drops to normal operating levels. After conditioning, the pack delivers current fast enough to absorb the transmit spike without the BMS intervening. If cutouts persist after three cycles, check that the contact strip is fully seated — a partial connection increases effective resistance at exactly the wrong moment.

Bar indicator showing one fewer bar than expected on a fresh pack

The TK-series radios read battery state using simple voltage-threshold steps — each bar on the display corresponds to a voltage band. A new Ni-MH pack ships at around 6.0–6.4V storage voltage, which sits below the top threshold, so the radio correctly shows one bar fewer than full. This is not a fault. After a full charge cycle the pack reaches 7.2V and the indicator moves to the top bar. Do not judge capacity from the first power-on reading — charge the pack fully before drawing any conclusions about its condition.