Fyi i tried the same thing i have a dw9107 charger and the 18v battery wont fit, i modified the battery casing a little and it charged the 18v battery just fine. i dont reccomend this as im sure isnt reccomended by dewalt! just a little personal experience. 14.4 is only 2.6v from 18 so what the heck it worked.

John windfeldt

FYI, I tried the same thing. I have a dw9107 charger, and the 18v battery won't fit. I modified the battery casing a little and it charged the 18v battery just fine. I don't recommend this as I'm sure isn't recommended by Dewalt! just a little personal experience. 14.4 is only 3.6v from 18 so what the heck it worked.