I bought a Lynx brand battery powered pole saw from Harbor Freight. It came with 1 battery and a 1 hour fast charger. It will easily handle work for 4 hours without charge with 1 person cutting and 1 person dragging brush off. Put it on charger at lunch break whether it needs it or not. Work the afternoon away.
I have cut several limbs off in the 6-8" diameter range and even cut the limbs up in easier to move size pieces once on the ground without swapping saws. Only complaint I have is, it doesn't have the reach that a gas powered pole saw has. It is several hundred dollars less, so that outweighs the height handicap. I believe I can reach about 15' feet with the saw (with angle to prevent bar pinch). It is really light so that my father in his 70s uses it some as well.
I have a lot of Ryobi 18 v tools and about 8 batteries. Most of my batteries are over 6 years old. If you are in the OKC area and need batteries for cordless tools, check out Advantage Battery. They carry a lot of them and their normal prices is the same or lower than the sale price at the big box store.From my experience if your dont use the battery powered units very often its not worth it the batteries will get to a point they wont hold a charge and then your stuck with either replacing the batteries ( which usually cost nearly as much as what your trying to power) or replacing the entire unit itself. Batteries needs to be cycled on a regular basis to keep a charge.