Koehler Lighthawk 600 Replacement Battery 7.4V 7800mAh

Koehler Lighthawk 600 Series — 7.4V Li-ion Replacement Battery (9B-1963-2)

This is a 7.4V 7800mAh Li-ion battery for the Koehler Lighthawk 600, Lighthawk 600 Lumens, and Lighthawk Gen II LED flashlights. It replaces OEM part 9B-1963-2 directly. At 57.72Wh, it matches the original cell configuration and voltage rail these lights run on.

• Lighthawk 600 and Gen II LED compatibility: These three models share the same 7.4V two-cell battery format, connector pinout, and BMS handshake protocol. Swapping between them without changing the battery platform was intentional in the Gen II refresh — same pack, updated driver board.
• Bench tested on actual hardware: We cycled this pack through full charge and discharge on a Lighthawk 600 body. The BMS held cutoff at the correct low-voltage threshold and balanced both cells within 20mV at full charge. No false low-battery triggers during the cycle.
• Multi-cell replacement timing: The Lighthawk 600 runs two cells in series. If you are mixing this new pack into a light that still has one aged original cell, stop — replace the full pack as a unit. A weaker cell drains first under the high-current draw of turbo mode and can be pushed below its safe floor by the stronger cell continuing to discharge through it.

Why the Lighthawk 600 steps down output before the indicator reads low

The Lighthawk 600 driver monitors cell voltage in real time and steps down output — usually from turbo to high or medium — before the battery indicator registers low. This is brownout protection built into the driver, not a battery fault. It activates when cell voltage drops under load, even if resting voltage still reads acceptable. If the light steps down frequently and early in a session, the battery's internal resistance has likely climbed — the cells can no longer sustain voltage under the current draw turbo mode demands.

Battery reads full but turbo mode lasts noticeably less time than it used to

Turbo mode on the Lighthawk 600 draws significantly more current than standard or high modes — often five to ten times more. A degraded cell may hold a surface charge that reads as full at rest, but voltage collapses the moment high current flows. The driver reads this sag as a low-voltage condition and steps output down within seconds. Charge the replacement pack fully before its first turbo session and confirm resting voltage sits at or above 8.2V before use.