Kenwood NX-200S KNB-33L Replacement Battery 7.4V 3350mAh

Kenwood NX-200S / NX-300S Series — 7.4V Li-ion Replacement Battery (KNB-33L)

This is a 7.4V, 3350mAh Li-ion replacement battery for Kenwood NX-series two-way radios. It fits the NX-200S, NX-210, NX-300S, and NX-410, among others. OEM part numbers covered include KNB-33L, KNB-41NC, and KNB-54N.

• NX-200S / NX-210 / NX-300S / NX-410 platform fit: These models share the same 7.4V battery rail, connector footprint, and BMS handshake protocol. One pack works across the group without modification or adapter.
• Bench tested on actual hardware: We ran this pack through full charge and PTT load cycles on NX-series hardware. The BMS handled transmit current spikes without triggering overcurrent cutoff, and the charger dock accepted the pack on first insertion.
• Contact strip care on first dock insertion: 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 Kenwood dock requires a clean contact cycle to complete the BMS handshake before charging begins.

Why the NX-200S cuts out mid-transmission on a new battery

During PTT, the NX-200S draws a sharp current spike — often 1.5A to 2A above standby draw — as the RF amplifier fires. A new cell shipped at storage voltage (around 3.6V–3.7V per cell) has higher internal impedance than a fully cycled cell. Under that transmit spike, the BMS reads the voltage drop as an overcurrent event and trips the protection circuit. The fix is straightforward: charge the pack fully to 8.4V before the first transmission shift, and the BMS will pass the spike without cutting out.

Bar indicator showing one fewer bar than expected on a new KNB-33L

The NX-series bar indicator reads voltage thresholds — it does not track stored energy. A new pack arrives at shipping storage voltage, which sits below the top threshold, so the radio displays one bar short of full even with a freshly inserted cell. This is not a capacity fault. Run a complete charge cycle to 8.4V, let the pack rest for ten minutes off the charger, then reinsert — the indicator will display correctly.