Same here -- I'll never go back to pump sprayers. What a difference and time saver. Seriously, buy and try it and if you don't like it take it back. I suspect you'll convert. I rotate three batteries as our electric weed eater shares the same size/type. I spray a lot and honestly I've never drained a battery after a couple of hours. Weed eater, yes, this backpack seems to go forever.Chapin. Purchased at Lowe’s about 5 years ago, and uses a Black and Decker 20V battery. It is comfortable to wear, has never clogged or leaked, and I liked the first one so much I went back and bought a second one to use just for herbicides. it seems that it is no longer made for B&D batteries, but Chapin has the identical sprayer with a different rechargeable battery system. It is pricey at about $160.
Once you go battery you will never go back.