{"product_id":"lighthawk-replacement-battery-74v-10200mah-li-ion","title":"LightHawk 9B-1963-2 Replacement Battery 7.4V 10200mAh Li-ion","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eLightHawk KLS600FX Series — 7.4V Li-ion Replacement Battery (9B-1963-2)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is a 7.4V, 10200mAh Li-ion replacement battery for the LightHawk KLS600FX series flashlights. It replaces OEM part numbers 9B-1963-2 and 9B-1963-3. The KLS600FX is a high-intensity LED flashlight used in search and rescue, tactical, and outdoor applications.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eKLS600FX series fit:\u003c\/strong\u003e\n    Both 9B-1963-2 and 9B-1963-3 share the same 7.4V two-cell Li-ion configuration, connector pinout, and BMS communication protocol — the flashlight driver reads charge state the same way from either part number.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this battery through full charge and discharge cycles on the KLS600FX platform. The BMS held the 4.2V per-cell ceiling without deviation and tripped the under-voltage cutoff cleanly at 3.0V per cell, protecting both cells equally.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eMulti-cell replacement rule:\u003c\/strong\u003e\n    The KLS600FX draws high current in turbo mode — up to several amps. If one cell is older than the other, its higher internal resistance causes it to sag faster under load. Replace both cells as a matched pair from the same batch to keep internal resistance balanced across the pack.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eWhy the KLS600FX steps down output before the battery indicator reads low\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThe KLS600FX driver monitors cell voltage under load, not at rest. In turbo mode, high current draw causes a temporary voltage sag below the driver's step-down threshold — even when the cells still hold a strong resting voltage. The driver interprets this sag as low charge and drops to a lower output mode to protect the cells. This is not a fault; it is the driver's brownout protection working as intended. Switching to standard mode at this point lets the light run at full output again because the lower current draw eliminates the sag.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eOne cell draining faster than the other in the KLS600FX pack\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eIf you mix a new cell with a partially degraded cell, the weaker cell has higher internal resistance and delivers less energy per cycle. Under the KLS600FX's high-current turbo draw, the weaker cell hits its under-voltage floor first, forcing the BMS to cut output to protect it while the stronger cell still has capacity remaining. Over repeated cycles this imbalance compounds — the weaker cell gets deeper discharges and degrades faster. The fix is to replace both cells simultaneously; check that resting voltage across both reads within 0.05V of each other before first use.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43377511694426,"sku":"BWCS-KLS600FX-1","price":54.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 2 Year","offer_id":43377511727194,"sku":"BWCS-KLS600FX-2","price":63.99,"currency_code":"USD","in_stock":false},{"title":"Warranty 3 Year","offer_id":43377511759962,"sku":"BWCS-KLS600FX-3","price":70.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-KLS600FX-1.webp?v=1778767205","url":"https:\/\/batteryweb.com\/products\/lighthawk-replacement-battery-74v-10200mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}