I forgot to mention, I purchased them through Walmart on-line (6 amp hour). I think my brother had problems with the 4 amp hour ones.
When we are doing projects up at the cabin over a long WE ... off the grid ... battery powered tools are indispensable. Luckly, they are getting so much better.
I updated to the 20V DeWalt (from 18 V) several years ago. Around the holidays, HD often has a "package" deal on them. I got the drill, impact, circular saw, reciprocating saw, grinder, vibrating cutter, and 90* drill all at the same time for a good price. The reciprocating saw also likes to eat batteries, usually cutting either plywood or pipe.
I also have purchased their battery powered leaf blower (for down here), the vacuum (indispensable up at the cabin), hedge clipper (lasts far longer than you think it will) and their battery powered tire inflator. No regrets with any of them. I still use my 18V 1/2 impact with a converter for the 20V batteries, works well.
The additional batteries come in very handy, especially if you have to cut a lot of 3/4" plywood, etc.