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  #11  
Old 12-03-2012, 07:01 PM
Darryl G Darryl G is offline
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Ok...so for a FSA 85, 2 batteries that together will give you up to 1 hour of run time, with a charger I costed it out at over $900. That gets you a 14 inch string trimmer running 0.08 line that you can't get wet or use in wet conditions. Sorry but I just can't see this as practical for commercial use unless you and your customers are dedicated tree huggers.
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  #12  
Old 12-03-2012, 07:23 PM
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Richard Martin Richard Martin is offline
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Quote:
Originally Posted by larryinalabama View Post
How do you caculate the cost to recharge batteries???
Just multiply the watts that the charger consumes by the time it takes by the price per KWH.

IE:

200 watt charger and it takes 45 minutes to charge. The electric company charges per 1,000 watts used in an hour. 1,000 divided by 200 is 5. Take your cost per KWH and divide it by 5. Then multiply that by .75 since you're only using 200 watts for 3/4 of an hour. If you pay 12.0 cents per KWH then your cost to charge the battery one time is 1.8 cents.
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  #13  
Old 12-03-2012, 08:44 PM
Monroe74 Monroe74 is offline
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Stihl electric handhelds

Darryl G do you know for sure that you can't get it wet or use in wet conditions?
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  #14  
Old 12-04-2012, 07:58 AM
Darryl G Darryl G is offline
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I read the owner's manual and that's what it says. Says not to use in very damp conditions either. See page 10.

http://www.stihlusa.com/WebContent/C..._85_Manual.pdf
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  #15  
Old 12-04-2012, 08:12 AM
Monroe74 Monroe74 is offline
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Ok thank you for the info
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  #16  
Old 12-04-2012, 10:07 AM
rlitman rlitman is offline
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Quote:
Originally Posted by Darryl G View Post
I read the owner's manual and that's what it says. Says not to use in very damp conditions either. See page 10.

http://www.stihlusa.com/WebContent/C..._85_Manual.pdf
Um, that sucks, and with the motor down by the head it is bound to get moisture. This is an application that screams for a brushless motor if you ask me, but I guess that's not what what they're using.

Now back to the cost: you've given me some real numbers to work with. Thanks.
What's the cost of that 140 gallons of gas, plus 2 gallons of 2cycle oil, plus a plug, air filter and fuel filter? Somewhere around $600, right?

Based on Richard Martin's charging cost estimate (which looks pretty well thought out to me), and 28 weeks, charging FOUR batteries each, once a day, 6 days a week, you're looking at $12.10 in electrical charging cost.

Four AP80 batteries (forgetting about the cost of the equipment for a moment) run about $600. That's about the same as the first season's worth of gas (even counting the charging cost). So the first year is about break-even.

Now, based on 28 weeks, 6 days a week, you're looking at hitting the 500 charge cycle count in just under three years. By then, they claim you will still have 80% of the battery capacity remaining, but even so, after the first year (assuming you need 4 batteries to get through one day's work), you're no longer paying for gas.
If you get 5 years out of the batteries (not counting equipment failures), you could have saved around $2350 (mostly in gas).

If you can get away with just two batteries to get you through the day, your break even time is cut in half.

Now for me, I'm just a homeowner who is interested in the math for the academic purposes. I've got too much tied up in my Kombi motors.
But if Stihl had a Li-Ion Kombi head that could compete with the KM110 for power, where I could still keep my attachments, and if it were brushless, I sure would think hard about that when it comes time to replace my engine.
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  #17  
Old 12-04-2012, 10:39 AM
Darryl G Darryl G is offline
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According to the specs you're only going to get a 15 minute run time off of the AP80 battery! I did my costing based on the AP160 which gives 30 minutes. And that's up to 15 and 30 minutes....For a homeowner I could see it but it just seems impractical to me for a pro.

I do have a B & D cordless hedge trimmer that I use for touch ups and little boxwoods, for one handed ladder work and when I'm climbing behind shrubs and a building. It's quite handy, but it's only a supplemental tool. I think the cordless stuff is great if you're not going to use it for extended periods.
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  #18  
Old 12-04-2012, 11:28 AM
rlitman rlitman is offline
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Ok, I didn't see the runtime numbers before. Sounds like I was a bit too optimistic (it did sound a little too good to be true).

15 minutes doesn't sound too good, but that's for how much time the string is spinning. Electric machines don't need to idle. Four AP160 batteries should give you 2 hours of run time. Do you really think it would be possible to drain four of them in one day?

Based on that (and the higher battery cost), the breakeven would be more like 21 months. That's still well under half the battery's lifetime.

Oh, and it looks like the cordless chainsaw is indeed brushless. I can't confirm if any of their other cordless tools are, but brushless motors are pretty tolerant of being run wet.

So the question is, would a pro actually get the full 30 minutes of working time on each battery?
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  #19  
Old 12-04-2012, 11:29 AM
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Richard Martin Richard Martin is offline
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I was not trying to say that any battery will run for any specific amount of minutes. I was only using 45 minutes as an example. Like I said originally, I did a cost analysis earlier this year and the electric trimmer lost. It really came down to a weakness in duration and life span of the batteries.
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  #20  
Old 12-04-2012, 11:32 AM
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Richard Martin Richard Martin is offline
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Something that hasn't been factored in is the irritation factor. If these are the type of batteries that give full power right until the end and then suddenly quits, imagine the irritation of having to walk back to the truck time and again just to change the battery.
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