My brother has a boat load of 18V "stuff"... Then the lith-ion 20V came out and it's pretty nice, he bought a few of those tools.
Anyway, he likes those 20V lith-ion batts so much, he made an adapter to use the new 20V batts in all of his 18V tools! IT works perfectly!
If you didn't already know, the 20V batts/tools run on 18V, so it a no brainer to run those batts on the 18V tools!
BTW, I think NOW, Dewalt makes/sells just an adapter to do this...
Lastly, "I" LOVE my Dewalt 20V tools too!
Lincolns legacy is, he freed the slaves
Obama's legacy will be, he freed the terrorist!