So you’ve got a bunch of 18V Dewalt tools that still work well.
And you’ve got one or two 20v tools around the shop. And maybe some of your 18V batteries don’t hold their charge any longer.
Update to 20V batteries and use them with all your 18V tools with this handy adaptor.
This adapter allows you to use select DEWALT® 20V MAX* Lithium Ion slide pack batteries with DEWALT 18V power tools.
However, word of caution from the reviews. It can be hard to remove and you need to remove the batteries when not in use. Also, it won’t work with certain DeWalt Premium batteries.
Not a perfect solution, but a fairly cost-effective way to get a few more years out of your cordless tools.