With an 18V to 20V battery adapter, you can use your DeWalt 20V batteries with older 18V tools. However, not all battery packs and drill models are compatible.
When cordless power tools initially became mainstream, their batteries were made of nickel cadmium (NiCd). One of their biggest limitations is the so-called memory effect, where batteries could no longer hold the same capacity when they were only partially discharged. You need to fully discharge them before topping them up again. These power tool batteries also lose a certain percentage of charge when you don’t use them. Like many other tool brands, DeWalt once offered NiCd-powered tools, specifically its 18V line. The company has since discontinued this range, replacing it with 20V power tools paired with Lithium-ion batteries (Li-ion) instead.
But with the phaseout of DeWalt’s NiCd batteries came the introduction of one problem: Can users of still-functional NiCd tools keep their gear? Unfortunately, DeWalt’s 18V and 20V power tool batteries aren’t completely interchangeable.
