Koehler Lighthawk 600 7.4V Replacement Battery 9B-1963-2

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

This is a 7.4V, 10200mAh Li-ion replacement battery for the Koehler Lighthawk 600, Lighthawk 600 Lumens, and Lighthawk Gen II LED flashlights. It replaces OEM part number 9B-1963-2 and restores full output across all drive modes. Capacity is rated at 75.48Wh — matching the original cell configuration.

• Lighthawk 600, 600 Lumens, and Gen II LED compatibility: All three models use the same 7.4V two-cell pack format with the same connector and BMS handshake. The driver circuit across this series expects the same voltage rail, so one battery fits all three without modification.
• Bench tested on actual hardware: We cycled this pack through full discharge under high-draw conditions replicating turbo mode. The BMS held steady at cutoff threshold, protected the cells from over-discharge, and accepted a full charge without cell imbalance flags.
• Multi-cell replacement timing: The Lighthawk 600 pack uses two cells in series. If you are running a second original cell alongside this replacement, the older cell will drain first under turbo-mode current draw. Replace both cells from the same batch at the same time to prevent one cell pulling the other below safe discharge voltage.

Why the Lighthawk 600 dims before the battery indicator reads low

The Lighthawk driver monitors pack voltage continuously and steps output down before the indicator trips — this is brownout protection, not a battery fault. When cell voltage drops under sustained high-current draw, the driver reduces LED current to keep voltage above the cutoff threshold. You will see noticeable dimming in turbo mode well before the indicator signals low. This is normal end-of-charge behaviour; switching to a lower mode restores stable output from the remaining charge.

Turbo mode running noticeably shorter than standard mode

Turbo mode on the Lighthawk 600 draws five to ten times the current of standard mode, compressing the usable charge window significantly. High current draw also generates heat in the cells, which causes temporary capacity suppression — the battery is not defective. The driver may also throttle output under thermal load, which some users misread as a weak battery. To confirm the pack is healthy, run a full charge and discharge cycle on standard mode and compare output stability throughout.