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The BL1840B is Makita's 18V LXT 4.0Ah lithium-ion pack, the mid-size battery in the LXT line. It claims up to 35% more runtime than the older 3.0Ah BL1830 and charges in 40 minutes or less on a Rapid Optimum Charger. It is built to keep working in cold, down to -4°F. The best new price is $76.97 at eBay as of November 7, 2026, with 7 stores listing it new.
In stockSold by ILUINTERP L.L.C.Returns: Sold by a Walmart Marketplace seller; returns go to the seller under the seller's returns policy.
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Availability unknownSold by essentialsdepot24 (99.7% positive, 43,700 ratings)Returns: Set by the eBay seller; the eBay Money Back Guarantee covers an item that doesn't arrive or isn't as described.
Availability unknownSold by we_are_tools (99.9% positive, 182,100 ratings)Returns: Set by the eBay seller; the eBay Money Back Guarantee covers an item that doesn't arrive or isn't as described.
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Lowest price we've seen: $79.99 on Nov 7 at Amazon. Tracked across 3 stores since Nov 7.
Owners of Makita LXT tools generally rate the 4.0Ah pack as a solid middle option: noticeably longer runtime than the 3.0Ah, quick to charge, and reliable in cold weather. Some wish for the runtime of a 5.0Ah on high-draw tools.
Provides up to 35% more run time per charge compared to the 18V 3.0Ah battery (BL1830)Reaches a full charge in 40 minutes or less on the Makita Rapid Optimum Charger (sold separately)Compatible only with Star Protection tools, indicated by the Star Symbol and/or Yellow Battery Receiver under the toolBattery delivers consistent power and runtime in extreme temperatures, even in winter (-4°F/-20°C)
