Can I use a 18V XR battery in 20V DeWalt?

As you might know, the difference between Dewalt 20V Max and 18V is essentially marketing in nature, rather than relating to electrical power. There is no functional difference between 20V Max and 18V!

18V is the nominal voltage for 5x 3.6V Li-ion batteries connected in series. 20V Max takes into account 5x 4.0V, which is the average maximum voltage at full charge with no load applied.

In other words, if you have a Dewalt 20V Max 5Ah battery from the USA and a Dewalt 18V XR 5Ah battery from Europe, they are – for all intents and purposes – the same exact battery but with different labels.

Cover the labels, and you shouldn’t be able to tell the batteries apart.

If there’s no difference where did “20V Max” come from, and why?

More than 11.5 years ago, back in June 2011, Dewalt announced their then-new 20V Max cordless power tool system.