Withdrawn Electric chainsaw efficiency vs gas.

[Hermio]

I put away my Stihl MS 500i for the season, but I had a bit of cleanup to do with a treetop, so I used a Kobalt 80 volt saw for that. I cut about 1/2 cord using 6.5 amp-hours at 80 volts. That works out to about 1 kW-h per cord, battery usage. Allowing for about 90% motor efficiency, it would be about a net energy usage of about 0.9 kW-h/cord. It took me about 1 hour to cut it, so that would be about 2 hours per cord. When I cut with my MS500i, I get a cord done in about an hour, so it is at least twice as fast. It uses about 53 ounces of fuel per cord. Energy density of gasoline is about 12 kW-h/kg or about 0.3 kW-h per fluid ounce, so the gross energy consumption is about 15.9 kW-h per cord. The saw itself has a maximum power output of 5 kW, so if it were running at full power the entire time, it would be about 31% efficient. But since it is loafing much of the time and idling some of the time, it is probably delivering at most 3 kW-h per cord. Still, that is much higher net energy used than the electric saw; perhaps triple. This may be because the Stihl uses 3/8" RS chain, and cuts about twice the kerf. I am not saying we should use battery saws. I like to get the job done quickly. And the batteries are way too expensive to keep enough on hand for using several hours at a time. (A 2AH battery has a run time of about 10 minutes on the Kobalt saw.) But I just thought it would be an interesting comparison.