I have a Stihl combi-system which includes a polesaw attachment. It’s electric with a lithium ion battery backpack that weighs at least 20 lbs.

I love the thing. I’ve felled trees that are up to 8 inches in diameter and done some real cleanup work around my property with it.

It might be possible to make something for me but the average heavy chainsaw user needs to be able to trek into the woods and spend significant time away from any power source. Furthermore, I want to be nimble and able to drop everything and run when a tree starts moving. A heavy weight strapped to my back for real tree work is a death trap.

Firefighters have even more stringent requirements for their chainsaws in highly demanding environments. If you want to convince anyone that an electric chainsaw is workable, convince them first. Everyone else will be easier.

I use my bigger chainsaws for bigger trees (just took down a mature Monterey Pine that dropped its last needle) and some Alaskan milling. The latter takes a lot of power for a single pass. I’m already lugging 22lbs just for the power head, making that electric with similar capacity to a tank or two of gas will be completely impractical in terms of weight. That’s especially so in rugged terrain.

If you want it to last longer than 20 minutes it would weight about 250 pounds.

Chainsaws are at the very corner of tools that have to be both portable, handheld, and very powerful. This means that their energy source should very dense. Lithium does not come close for the big saws.

Urban tree climbing arborists (that need a small saw to chop limbs while up in a tree) now sometimes use battery powered saws that run off of an "umbilical"- a cable off of the saw runs to a separate (backpack or other container) battery. These saws are among the smaller chainsaws (maybe a 12" bar, sized for chopping limbs). The other extreme is a saw for bucking and felling medium and large trees, which uses a MUCH more powerful motor and a 30" bar or bigger.