{"product_id":"firestorm-fs1800cs-replacement-battery-18v-4000mah-li-ion","title":"Firestorm A18 18V Cordless Drill Replacement Battery 4000mAh","description":"\u003cdiv class=\"bpw-desc\"\u003e\n  \u003ch2 class=\"bpw-desc-h2\"\u003eFirestorm FS1800CS Series — 18V Li-ion 4000mAh Replacement Battery (A18 \/ FSB18)\u003c\/h2\u003e\n\n  \u003cp class=\"bpw-desc-lead\"\u003eThis is an 18V 4000mAh Li-ion replacement battery for the Firestorm FS1800CS series. It fits the FS1800CS, FS1800D, FS1800D-2, FS1800ID, and over 21 additional Firestorm 18V cordless tools. Capacity is 4000mAh (72Wh) as specified in the product data.\u003c\/p\u003e\n\n  \u003cul class=\"bpw-desc-bullets\"\u003e\n    \u003cli\u003e\n\u003cstrong\u003eFS1800CS platform fit:\u003c\/strong\u003e\n    All listed models share the same 18V rail, connector footprint, and BMS handshake protocol. The pack communicates state-of-charge directly to the tool's onboard electronics — swapping in this battery does not require any firmware or hardware modification.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eBench tested on actual hardware:\u003c\/strong\u003e\n    We ran this pack through repeated trigger-pull cycles on an FS1800D drill to verify BMS overcurrent thresholds. The protection circuit handled motor-start inrush without nuisance tripping, and cell voltage recovered cleanly between draws.\u003c\/li\u003e\n\n    \u003cli\u003e\n\u003cstrong\u003eMotor inrush break-in:\u003c\/strong\u003e\n    On first use, run the tool at half load for two cycles before pushing maximum torque. This lets the BMS log the motor's inrush current profile and set accurate overcurrent thresholds — reducing the chance of nuisance cutoffs during heavy drilling later.\u003c\/li\u003e\n  \u003c\/ul\u003e\n\n  \u003chr class=\"bpw-desc-divider\"\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eBMS cutoff on drill motor-start inrush surge\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eWhen you pull the trigger on a stalled or high-load application, the motor draws a spike of current that can be three to five times the steady running load. If the BMS has not yet profiled the motor, it may read that spike as a fault and cut the pack. This is not a battery defect — it is the protection circuit doing its job with incomplete data. Two half-load break-in cycles let the BMS establish a current baseline so it tolerates normal inrush without tripping.\u003c\/p\u003e\n\n  \u003ch3 class=\"bpw-desc-h3\"\u003eTool bogs under load but doesn't cut out completely\u003c\/h3\u003e\n  \u003cp class=\"bpw-desc-p\"\u003eThis is voltage sag — cell voltage drops under sustained draw and the tool loses torque without the BMS triggering a full shutdown. The most common hardware cause is high contact resistance at the battery rail, usually from oxidised or debris-fouled terminals. Clean the pack and tool contacts with isopropyl alcohol, let them dry fully, then retest. Under normal load the rail voltage should hold above 16V; consistent drops below that point to either degraded cells or a contact resistance problem at the connector.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"BatteryWeb","offers":[{"title":"Warranty 1 Year","offer_id":43416012980314,"sku":"BWCS-BPS180PX-1","price":99.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 2 Year","offer_id":43416013013082,"sku":"BWCS-BPS180PX-2","price":116.99,"currency_code":"USD","in_stock":true},{"title":"Warranty 3 Year","offer_id":43416013045850,"sku":"BWCS-BPS180PX-3","price":129.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/4775\/0746\/files\/BW-CS-BPS180PX-1.webp?v=1779759461","url":"https:\/\/batteryweb.com\/products\/firestorm-fs1800cs-replacement-battery-18v-4000mah-li-ion","provider":"BatteryWeb","version":"1.0","type":"link"}