I've run my scarifier on 2.5Ah, 4Ah and 5Ah, and and mix. It didn't care, unless you're digging the blades deep into the ground (not sure why you would) it's pretty light work. I wouldn't worry about getting high capacity batteries just for the scarifier. I already had those batteries and didn't want to need to buy more to get a matching pair. Ryobi said it will run fine, will just run till the lower capacity battery is empty.