The first thing is to be equipped with is the best hand tools. Usually a good Japanese manual pruning saw goes through wood so quickly that power to cut anything less than 2" diameter should be a waste of time. After that a small chain saw is what most professionals use- I don’t go for mine until diameter exceeds 4" except in big jobs where I run through with the chain saw first.
If you don’t have something like a long handled Bahco ultra-light loppers, Silky Gomtarro 300mm course cut saw and an ARS or at least a Felco hand pruner you probably don’t know how quickly you can go through trees with very little non-manual power.
Typical bearing age peach trees (say 6" diameter with a 15’ spread) or similar sized trees take me under 10 minutes to prune- for peaches, often only 5. A sawzall would not speed up the process in any way I can picture. Some pros do like to use a powered hand pruner but I’ve never tried one. I can’t picture that saving a lot of time for me either, because I’m usually in top pruning shape from doing it almost 7 months of the year. It is the only task I can still perform more quickly than my younger and stronger help.
If a sawzall or anything besides a good chain saw helped speed the process, I expect commercial growers would employ them with their hundreds of acres of trees to prune. Pruning is one of the most expensive operations in a free standing tree orchard.
Sawzall would do the job, but is overkill for most stuff. Downside also is the weight of the saw to carry around continuously (5lbs or more) and the fact that it wouldnt fit in some spots that you might want to cut. Plus you wont just slip it into a sheath on your hip when you need 2 hands for something else!
I know some bamboo growers use a sawzall to cut back bamboo. I’ve been able to keep my bamboo in check by cutting down news shoots with the riding mower. Will likely have to do some selective cutting eventually, and will probably use a sawzall for that.
For fruit tress I just use manual hand tools. Seems like a good idea, though, if you’re pruning that many trees.
I do use ARS hand pruners per your suggestion and they are the cats ass. My hand held course cut saw is a generic home depot model and im just not real impressed with it most the time. Are the Silky’s that much better? Have a good chainsaw but its a larger model and not much fun to manuver in tight quarters. Thats where I was thinking that the sawzall would come in handly. For that 4"-6" stuff that is a pain with the hand saw. Stuff 1-3" is pretty quickly dispatched with the hand saw, bigger stuff is a chore.
Sounds like you need a small and light chain saw. I can’t make any recommendations unless you want to spend about $560 for the Stihl topping saw I use. It’s so light you can operate it with one hand and so powerful you could easily end up one handed if you lose focus.
There is a big difference between hand saws. The Taiwan made blades tend to bind and a 300mm blade is long enough to cut through the 4" stuff quickly but for 6" the chain saw is the ticket.
Not sure if your asking how long a charged battery will hold after charging without use or how long will the charge last while in use.
The newer lithium type batteries can be charge and will hold the charge several months in storage.
While in use is a difficult question to answer because ir just depends on how much your using the saw. I have more than one battery and I have never had an issue.
Just wanted to mention how handy the Ryobi chain saw is also. My use is small scale so it is difficult for me to even attempt to decide how practical these cordless tools would be on a bigger scale. They work well for my use.
I’d need a couple thousand feet of cord to use an electric chainsaw here. If your trees are close to home then an electric model makes good sense (I’d assume anyway, no idea about longevity of electric chainsaws vs. gas)
A small Stihl MS170 is a no-brainer. You can get them for $179.99 and it will mow through any task piece of wood growing on a fruit tree. Sure, you aren’t going to use it to fell 150 year old oak trees but it will work for anything you’d use it for. Anyone that has trees should own a chain saw.
And until you have used a small, decent quality chain saw like that you won’t have the comparison that will likely demonstrate why commercial orchardists turn to such a tool for cutting branches and not something designed for carpentry.