Electrified Yard Equipment Hauls Grass

mower2

[AmpEater] spent the summer converting yard equipment from internal combustion to electric power. The conversions run from a relatively tame Wheel Horse, to an insane Cub Cadet. The Wheel Horse lost its Kohler engine in favor of a hydraulic pump motor from a crown forklift. 48 volt power is supplied by MK lead acid gel cells. An Alltrax 300 amp controller keeps this horse reigned in.

On his Reddit thread, [AmpEater] says he is especially proud of his Cub Cadet zero turn ride on mower. For those who aren’t up on lawn implement terminology, a “zero turn” means a mower with zero turning radius. Zero turn mowers use two large wheels and tank style steering to turn within their own radius. We bet this style mower would also make a pretty good robot conversion, however [AmpEater’s] zero turn is still setup for cutting the grass.

After pulling the V-twin motor the 48 volt Motenergy ME-1004 was put in place. Batteries are 3 x Enerdel 48V 33 amp hour lithium ion packs. The packs are wired in series to provide 144V nominal. Right about here is where our brain started to melt. A 48V motor on 144V has to mean magic smoke, right? This is where the motor controller magic comes in.

[AmpEater] used Evnetics soliton-jr motor controller. The controller appears to be operating as a DC to DC converter, dropping the 144v down to a safe 48v for the motor, as well as providing a host of other features. Even with a switcher dropping the voltage down, there is quite a bit of heat generated in the controller. The Soliton has liquid cooling capability, and [AmpEater] is experimenting with a Koolace PMP-450 system. We’re a bit worried about a PC cooling system standing up to the vibration and abuse a 50” lawn mower can dish out though.

In case you’re wondering, this is not a cheap conversion. The motor retails for over $500 USD, and the Controller for around $2100 USD, and the batteries are around $4500 USD per pack. That’s more than double original price of the Cub Cadet.  Understandably, these conversions would be outside the realm of the average homeowner, but they may be worthwhile for a commercial gardener. Even with the recent push toward 4 stroke motors, small engines are still major polluters. We wish we could say an electric mower is quieter than a gas-powered one, however as the video shows, much of the noise lawn mowers create is the blades themselves.

Comments

  1. confused says:

    Yea, throw money at an idea. Heat=loss, commercial no way, solar panel would take way way too long to charge that battery pack. check out http://www.youtube.com/watch?feature=player_embedded&v=qgKfvNkJjcU

    • Heat = the inevitable result of switching DC power. Solar panel doesn’t charge the swappable high-voltage battery packs, it runs the 12v system which engages the main contactor, cools the motor, runs the pump, and activates the electromagnetic clutch for the blades.

      • rasz says:

        so what you are saying is Solar panel is there FOR SHOW ONLY

        • Nope, not at all. It keeps the 12v system operating. Got to run the pump and engage the blades somehow.

        • Do you honestly believe there is a big difference between a device which puts 50 watts into the HV pack and then converted to 12v and 50watts pulled vs. a device which just puts 50w into the 12v system? I’m avoiding a LV -> HV -> LV conversion, dude man

          • phlt says:

            I honestly believe that solar is as good here as it werent there. If it works only for 12V system, than it needs also it’s own batteries – you can’t stop if suddenly a cloud comes, what’s the point of having another package of batteries only for that? Also, right me if I’m wrong, it shall be lead battery, or if it’s some kind of lithium than again it should have charger for lithiums, and low voltage cut off (needed by battery.)
            I know that it’s conversion – and it looks nice and so on, and I like it as it is. I just don’t see too much sense in it :)

          • The mowers stock 12v system/battery is left unchanged. But it needs to be charged somehow. For less than the price of a nice 12v charger I got the sun to do it for free forever, with 0 user input.

          • phlt says:

            Ok, than it’s nicely thought, congrats! I’m always skeptic when I see solar batteries, but here they may pay of. Now I’m curious: this kind of machines have alternators? And if yes, did you leave it in system?

          • Tim says:

            Tesla Motors vehicles have a separate 12V battery for the radio, switching relays, etc. Why be skeptical of solar panels and batteries, when they just work? It’s like saying a survivalist can’t get potable drinking water by collecting morning dew, but they do (pun). Every drop in the bucket counts.

            I don’t understand how anyone could bitch about this awesome build, or solar power for that matter.

  2. polytechnick says:

    Gotta love that 70’s garden tractor with LED headlights! Seriously though, I hope there will be more of electric yard equipment out there. Gas powered ones are obnoxiously noisy. By a funny coincidence, as I’m typing this, landscaping company that takes care of the development I live in is mowing grass on my backyard. I can barely hear myself thinking :) In addition to the mufflers that are pretty much missing, those gas mowers have no catalytic converters. I read someone calculate a while ago that gas powered mowers around Los Angeles create more CO2 emissions than all the planes flying into LAX during the same time period. It’s high time those gas guzzling noisemakers started to use electricity. Great job on the conversion, AmpEater!

    • Wut? says:

      Ok, so if his battery bank has 33 amp hours of capacity at 144V, and he’s basically using a controller to turn it back into 48V, then using a motor which according to the company specifications is 300 amps peak at 48V, but only ~150 amps at normal operation………

      He is getting what, Maybe somewhere in the 1 hour range for his run time??? Most of the power in one of these units goes to the blades if I remember right, meaning that even when it’s not moving that fast and is “idling” it’s still using a lot of power…..

      I don’t know…… If he spent more than $16,000 on parts alone to make a lawnmower which has about 45 minutes of runtime maybe?? That kinda seems like an enormously shameful act of waste. I mean….. this isn’t exactly cutting edge research here, and that kind of money could have done a lot more for people….. It’s just the whimsically indulgent side of this kind of stuff gets to me sometimes….. I don’t know.

      Not trying to be trolling here, but I am kinda shocked by the pricetag on this one.

      • No, you have a valid point. You can buy an electric ride-on for a fraction of that price and a hybrid would be more practical, doubles as a generator and a four wheeler.

        • Electric equipment costs more upfront but operating costs are a fraction of gas. A mower can easially go through a gallon an hour, but 4kwh for 1 hour only costs 50 cents where I live. The ~$4,000 difference will be made up after a little more than 1,000 hours of operation.

          • Chris C. says:

            If run time is an hour, then 1,000 hours of operation is at least 1,000 cycles on the Lithium Ion battery, and it’s time to replace it. If not already overdue. There goes the $4,000 you saved.

            I think electrics are cool. And I like your conversion despite what anyone says. But claims of savings or breakeven based *only* on upfront costs and the cost of gas vs. electricity, while ignoring other major recurring costs, aren’t honest at all.

          • These Enerdel cells have a rated life of >3000 cycles and >10 years.

          • Please, continue to call out my honesty while pulling numbers out of your butt that don’t align with simple google-able reality

          • phlt says:

            But you have to be quick, if you are not, than next half of lawn will have to wait till batteries are charged :)

          • 2 packs + EMW 12,000 charger = 24/7 mowing with no waiting to charge

          • Chris C. says:

            [upstateelectric607], I tried Googling it before I posted, and the datasheet containing the complete longevity info isn’t available except by request. So I admit I did pull that number out of my butt. (Although the single-number cycle rating is always optimistic, and you’re likely to see less in the real world depending on DOD and storage conditions.)

            Compounding that, it appears HAD pulled the $4,000 battery cost out of their butt too, as I see now it only cost $1,500. My apologies. Disregard my previous comment as nonsense.

      • If a $16,000 mower makes you shed a tear for humanity then you’ll not want to look up the prices of commercial zero turns. And I’m not sure where $16 grand came from anyway – total conversion cost was $4,000 total, half of that for a battery pack. And the batteries aren’t a cost associated purely with mowing; the pack plugs into my electric truck for added range, and it plugs into my wood chipper, snow blower. welder, plasma cutter (no grid power in the shop).

      • polytechnick says:

        C’mon guys, this is Hackaday, not Thriftaday. Yes, it’s expensive. So were first cars, computers, what have you. Somebody has to demonstrate that there are no laws of physics to preclude the existence of such device. The guy was willing to spend his own money doing it, kudos to him for that! Only then can someone (else?) try to manufacture the thing to keep the costs down. Maybe rechargeable ride-on mowers won’t see Home Depot shelves anytime soon – who knows? – but that’s not the point of hacking, at least not for most hackers.

        • That’s true, but on the flipside, I hack stuff not just because it doesn’t exist yet (at least not the way I want it) or because it’s more fun, but because it’s often cheaper. Having someone else do the work would be way too expensive, and that’s still often too true of commercial products that have mass-production in their favor. Hacking and Thrift go together most of the time, even if the particular project is “expensive”.

    • fartface says:

      The blades spinning on my lawnmower is 90% of the noise over the engine. This will still be loud.

      • andarb says:

        The scissor cut of a push-style mower is a lot quieter, but it’s harder to keep it cutting properly. Easier to just swing a blade really, really fast than to bring two blades together when sticks, rocks, dog eggs, and other debris can jam the works.

      • polytechnick says:

        I have just few minutes ago had an opportunity to see and hear a slightly larger commercial-grade zero turn ride on mower with just the engine running(idling), engine running and transmission engaged (rolling on asphalt), engine with blades engaged idling, engine and blades cutting grass (of various density), all within not even 50 feet from where I sit and type this. Engine alone definitely accounts for most noise, hard to tell how much but nowhere close to as little as 10%. The mufflers on these things are a joke, they just don’t have much power to waste on muffling the exhaust, so they don’t. An electric mower will for sure be significantly quieter, and the type of the sound will be more bearable (think plane/heli prop kind of sound – I can live with that), not the high pitch metallic knocking noise characteristic of a small ICE with no muffler to speak of.

  3. TacticalNinja says:

    So, it’s bit coin operated?

  4. rue_mohr says:

    I have a bladeless tractor I’m converting, still under tests but so far its gonna be 3x 1.6kw vacuum motors, and lead acid batteries, homebrew controller (if any, hehe)
    I’m glad to hear a real price on how much the li-ions are worth.
    As for above comments, I’m sure if the motor WAS running at peak, it would only last 45 mins, its a good thing that people generally grossly over assume how much power just driving around takes, I’m guessing it pulls maybe 746W traveling, 144V, 33Ah = 4.7Kwh, so he may get somewere in the order of 4 hours.
    Dont confuse PEAK power with continious draw.
    Usually engines have to be working their crank off to put out their rated power, and only put out that much when they are new, and and and.
    Good project, thanks for sharing!

    • TacticalNinja says:

      not just when they are ‘new’, that peak power may also refer to running the motor from the ‘off’ state to actual movement. It’s like trying to push a heavy object, it takes effort to get that object moving, but once it’s moving you only need to exert less effort.

  5. Paul says:

    What is the efficiency of the DC to DC conversion? Would it not be better to have the batteries run closer to 48 volts with a larger amp hour reserve?

    • The Soliton Jr. stats show 0.8v drop to be typical, so the process is greater than 99% efficient. The problem with using a lower voltage is that when the batteries drop off over their discharge curve at some point they can no longer spin the motor fast enough to cut. So you get snappy performance from 60v to 48v, but the batteries aren’t fully discharged until 35v. I wanted a pack that would put out full power until 0% capacity remaining. Even when my batteries are fully drained at 90v it is well above the necessary motor voltage 48v.

  6. Bunedoggle says:

    That solar panel is MAYBE 30 Watts. It would take 160 hours to charge those batteries. Or add about 30 seconds of mowing time. I’m guessing it’s for looks.

    • mniel says:

      Maybe, but I could see as just a way to keep the charge topped up between uses, maybe? Or perhaps even charge it if you cut your grass as infrequently as I do :)

    • mojojoe says:

      Possibly, but if it is only used for an hour or two mow, and only half drained, that leaves 80 hours of charge required, which could be possible in a week in some climates. I wouldn’t expect the solar panel to be the sole power source, perhaps just left to trickle charge the batteries and then gets plugged in the day before it is required to top it off.
      Probably will get frequently filthy though…

    • It’s a 50 watt semi-flexible panel. It’s not for charging the HV battery, it keeps the 12v system running and charged up. Otherwise I’d need to charge/swap 2 different batteries, or run a DC-DC from the HV pack to the 12v battery. The panel takes care of this without any parasitic draw.

  7. RP says:

    Something to extend battery life further: The blade speed can be slowed or stopped when the mower is moving slower or not all. The power to overcome windage is pretty significant on a large deck.

    The blade tip speed can be kept proportional to the wheel speed as long as you keep above the minimum speed necessary to eject the clippings out the chute.

  8. static says:

    I have around 3 acre I need to try to keep clean, 4 if I try to keep up with the Jones’, o it’s easy to dismiss an electric at first glance. However considering the ICE on lawn tractor give me a problem, an electric starts sounding good. Of course if a had my way I’d have an agricultural compact tractor with front end loader,both a belly mower deck, a brush hog style to hang of the back. Alas I can day dream in one hand, and crap in the other to see which gets full first. Great hacks though, doing things in a manner that I wouldn’t thought of, of course that’s why I burn time visiting here near daily.

  9. limbo says:

    I’m guessing there aren’t cheaper batteries availible with better, or comparible energy density?

  10. Greenaum says:

    Nobody seems to have asked yet… why run 3x48v in series for 144v, then convert back down to 48v?

    • Willaim says:

      upstateelectric607 says:
      October 2, 2013 at 7:31 am

      The Soliton Jr. stats show 0.8v drop to be typical, so the process is greater than 99% efficient. The problem with using a lower voltage is that when the batteries drop off over their discharge curve at some point they can no longer spin the motor fast enough to cut. So you get snappy performance from 60v to 48v, but the batteries aren’t fully discharged until 35v. I wanted a pack that would put out full power until 0% capacity remaining. Even when my batteries are fully drained at 90v it is well above the necessary motor voltage 48v.

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