Need thoughts on battery operated sawsall

I have a Ridgid 18V and a Dewalt 18V. (got the Dewalt at a garage sale.... too good of a deal to pass by since I already had Dewalt batteries for other tools)They both work well but tend to use up batteries pretty quickly. Take several spare batteries to a junk yard run. Certain blades seem to use up batteries faster than others and that seems to be different between my saws.