Yes, if the voltage is the same. We need to look at this question carefully, though, because there are a few alternatives:If you already own a 20-volt Max DEWALT battery, it will work with 20-volt XR DEWALT chainsaws. You can put it in the XR charger, too. However, you can’t charge the XR batteries in the Max charger.Other brands of 20-volt Max batteries probably won’t fit.You can’t normally swap voltages around. A 20-volt Max or XR does not generate enough power for a 40-volt chainsaw. You can’t go the other way either. For example, a 40-volt battery won’t work on a 20-volt tool. The exception is the Flexvolt battery, which can be switched between compatible 20- and 60-volt tools (but, oddly, not 40-volt).