You would be better off buying a small gas chain saw. Do you really want to haul the weight of a large car battery and everything else out to a site? With the power needed, the battery won't last very long either.

The newer electric saw batteries can do a medium size tree with just one charge -

And they are getting better and better:

http://www.stihl.com/msa-160-c-bq-cordless-battery...

It could be done with a power inverter. They have Highly portable ones that are light weight that run on gas.

;-)

Battery??? No need.

Plug it in to a currant bush or locally available specie...;)

like this

http://www.sears.com/oregon-cs250e-40v-cordless-li...

i would also look into a reciprocating saw with a pruning blade

like this

http://www.sears.com/dewalt-dc385k-18v-cordless-xr...