PDA

View Full Version : Stihl electric handhelds


Monroe74
12-02-2012, 10:52 PM
Is anybody using them if so how do you like them?
How long do they actually last ?
How are you charging them during the day?

Richard Martin
12-03-2012, 06:49 AM
I did a sort of cost/benefit analysis earlier this year. When you look at the cost, lifespan of equipment and batteries and other little factors, it doesn't make sense to try to go all electric. The killer is the batteries and that holds true no matter what environment you look at, whether it's outdoor power equipment, solar power for your house or automotive.

The batteries are good for about 45 minutes and then they have to be recharged. And as the batteries are cycled they loose a little ability to maintain a charge for a specific amount of time. When they're new they are good for about 45 minutes. As they age the time goes down that they will hold a charge. By about 500 rechargings, the batteries are so weak that they have to be replaced.

For a solo operator it goes something like this. If in an 8 hour workday you use a trimmer for 3 of those 8 hours. That's 180 minutes. You'll need 4 batteries just to work one day. Bear in mind that that the time the battery is good for goes down each time the battery is recharged. So by the time you get to the end of the battery's lifespan you'll probably need 6 batteries just to use the trimmer for 180 minutes.

Do you see where I'm going with this? It is cost prohibitive.

Monroe74
12-03-2012, 08:26 AM
Thank you for your cost analysis but I was looking for real world experience.

rlitman
12-03-2012, 11:36 AM
Thank you for your cost analysis but I was looking for real world experience.

I too am curious about this. The cost analysis route is interesting, but seems far lacking. For one thing, I would be impressed if you could keep your string trimmer engine running for 3 hours every day. But with an electric, if your finger isn't on the trigger, you're not using battery. There is no cost to idle. So 2 hours is a more realistic amount, but I suspect that it is even less than that (depending on the site).
Now you're back to 4 batteries. And should get at least 2 years of life from them.

Here's a simpler way of looking at it though. Forget how many batteries you need on-hand. That just confuses things.
With 45 minutes of run-time and 500 charges, that's 375 hours of operation for each battery. Accounting for idle time, let's say that's the same as 500 hours of gasoline operation. Assuming you burn a quart an hour (and I freely admit I pulled this number out of my butt), that's 125 gallons of gasoline you burned (probably with the added cost of 2-cycle oil), vs an almost negligible electrical cost of charging the batteries.

Ok, so there is a pretty high up-front cost, but the savings look like they can be real.

Makes even more sense, when you realize that 500 hours of engine time on a 2-cycle engine without any repairs is optimistic.

But all this thinking makes me want to hear some real world cases all the more.

Richard Martin
12-03-2012, 11:52 AM
I too am curious about this. The cost analysis route is interesting, but seems far lacking. For one thing, I would be impressed if you could keep your string trimmer engine running for 3 hours every day.

Alright then. Do the analysis based on a trim man on a crew using it for closer to 8 hours a day.

orangemower
12-03-2012, 03:59 PM
Alright then. Do the analysis based on a trim man on a crew using it for closer to 8 hours a day.

That's not being fair. What solo guy is going to be trimming 8hrs a day? I think the idea here is to see how long it would last for a solo guy doing X amount of work a week or day for that matter. I know that I could get away with using a trimmer and blower on most of my properties without needing any recharge for a day if I had 4-6 bats. I don't see it being any good for a larger company with multiple crews using it all day, everyday.

Darryl G
12-03-2012, 04:44 PM
Just get a power inverter for your truck and a really long extension cord!

I read about a guy who used all battery equipment on lawns. He had a solar panel on the roof of the truck. He sold it as a premium service. Depending on where you are you might find enough "environmentally conscious" customers to make a go of it, but I think it's impractical for the most part unless you have all really small yards.

rlitman
12-03-2012, 05:13 PM
Alright then. Do the analysis based on a trim man on a crew using it for closer to 8 hours a day.

Ok, but what I'm trying to say is it doesn't really matter how many hours per day you're running the equipment to see if battery pays off over gas.

The number of hours per day just tells you how many batteries you need to own, but if you double the number of batteries you own, you also get double the number of hours out of them before they wear out. This all divides out.
So, yes, the initial investment for someone who runs the equipment a lot may be high because you need to buy more batteries, but that's not relevant to a cost/benefit analysis when comparing to gas.

The question is how much does one time unit (lets say 100 hours) of operation cost. That's the only way we can make an apples to apples comparison of dollars.

Monroe74
12-03-2012, 06:32 PM
If you were to buy a new 2cycle trimmer and two gallons of 2cycle oil. 1 spark plug, air filter, fuel filter, and 140 gallons of gas. Which is what one of my guys use for a 28 week season. The cost of the Stihl battery powered trimmer with 3 batteries and a charger. Come out to about the same at the end of year. With gas spread out over the course of the year and the electric all up front.
So the second year the 2 cycle user still has the same costs as he did the year before prices being the same. Where as in theory the electric user would only have to buy batteries about 60 a piece. So that being said the second year electric user makes out better.
What I want to know is if you are using one do you like the way it performs. Does it do as advertised?
What issues have you had with it? I.E. you got caught out in the rain and it stopped working.
If you need to charge the battery how are you doing it? I.e. solar how are you doing it? Inverter what issues are you finding with the vehicle ?starting etc.

larryinalabama
12-03-2012, 06:55 PM
How do you caculate the cost to recharge batteries???

Darryl G
12-03-2012, 07:01 PM
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.

Richard Martin
12-03-2012, 07:23 PM
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.

Monroe74
12-03-2012, 08:44 PM
Darryl G do you know for sure that you can't get it wet or use in wet conditions?

Darryl G
12-04-2012, 07:58 AM
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/CMSFileLibrary/instructionmanuals/FSA_65_85_Manual.pdf

Monroe74
12-04-2012, 08:12 AM
Ok thank you for the info

rlitman
12-04-2012, 10:07 AM
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/CMSFileLibrary/instructionmanuals/FSA_65_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.

Darryl G
12-04-2012, 10:39 AM
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.

rlitman
12-04-2012, 11:28 AM
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?

Richard Martin
12-04-2012, 11:29 AM
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.

Richard Martin
12-04-2012, 11:32 AM
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.

rlitman
12-04-2012, 11:33 AM
Right, but Darryl G pointed out that Stihl actually has run time estimates in minutes in their specs. Yes, it really does seem like the battery capacity is the limitation.

Oh, and the funny thing is that from a homeowner perspective, cordless may actually make less sense. Li-Ion batteries only last 7-10 years, whether you use them or not. All batteries eventually go bad, just on the shelf.
If you wouldn't have used enough gas to equal the up-front cost of the batteries over that much time, gas may actually be cheaper.

rlitman
12-04-2012, 11:55 AM
They are that type, but there is a charge level indicator with 4 LED's on the bottom, so you should have some warning.

Darryl G
12-04-2012, 11:55 AM
They do make a hip-mounted battery pack holder and a spare battery holder for it. http://www.stihldealer.net/productdetails-dealer-_ajjnda-prodid-939-toplvl-170-catid-171-subcat-170-catprods-171.aspx

Monroe74
12-04-2012, 12:50 PM
So 2 cycle oil runs 32.00 a gallon
A retune kit with the air filter, fuel filter and plug 15.00
Gas around me is going for 3.539 a gallon
For sake of an example echo Srm 225 200.00
Total 749.26

The battery trimmer
2 batteries @ 260 each 520
Trimmer. @ 300
Rapid charger @90
Total 910

I think the factor that even I forget is just because the trimmer is in my hand doesn't mean I can count the time moving from one obstacle to another as run time.

I personally believe that this is not the end all be all but an additional tool that could be used. For example if I wanted to start at a complex earlier then 8am I would be able to because the trimmer would make significantly less noise then the gas powered one.

The last question I have it how would you figure a charging cost if you are using your vehicle as the point of power?

Richard Martin
12-04-2012, 01:44 PM
The last question I have it how would you figure a charging cost if you are using your vehicle as the point of power?

Recharging costs are negligible which is why I never mentioned them. As I pointed out above, running a 200 watt charger for 45 minutes only costs 1.8 cents. But... Even if you do use a vehicle to charge the batteries, then the cost per charge should also include the 1.8 cents plus the cost of the inverter divided by the expected lifespan, in hours, of the inverter.

Bear in mind that even though the power for the inverter is coming from the vehicle, that power still must be created by the vehicle and therefore, has a cost.

rlitman
12-04-2012, 04:14 PM
>I think the factor that even I forget is just because the trimmer is in my hand doesn't mean I can count the time moving from one obstacle to another as run time.

That was what I was thinking. The run-time may not sound that long, but the question is really how much can you get done with it. Do you really spin the string for an hour in a day, or even more?

>I personally believe that this is not the end all be all but an additional tool that could be used. For example if I wanted to start at a complex earlier then 8am I would be able to because the trimmer would make significantly less noise then the gas powered one.

Interesting. Again, my perspective is skewed as a homeowner, but I personally work weird hours, which leaves me gardening at weird hours.
I bought a BR500 blower knowing that I was sacrificing power, for something that I could regularly use (sometimes after dusk) without annoying my neighbors (or waking the children).
I think professionals might feel that sacrificing power for quiet is a bad tradeoff, but they say that these units are "professional" power, whatever that is worth.

>The last question I have it how would you figure a charging cost if you are using your vehicle as the point of power?

Well, this is a little more difficult. An engine at idle wastes so much energy that a little extra strain on the alternator may not be measurable at all. OTOH, the efficiency of a car/truck engine is MUCH lower than the efficiency of a power company's generator.
I'd venture to say that at a worst case, assuming you don't idle your vehicle more just to charge batteries, the cost of charging in vehicle might be 4-5x the cost of charging from utility power.
My original assumption was you'd have enough batteries and chargers in the shop to have enough batteries ready to grab in the morning and go (so you wouldn't need the quick charger).