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Re: FW: solar lawnmowers

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  • James Ferrill
    ... Hey Kevin, Thanks for the input. Here s some more info for you. ... interest. ... esp. ... designed. Yeah, I don t like the fact that it s *all* plastic
    Message 1 of 1 , May 21 10:15 PM
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      >
      > ----- Original Message -----
      > From: Kevin L. Conlin
      > To: hregSent: Tuesday, May 16, 2000 6:27 PMSubject: solar lawnmowers
      >

      Hey Kevin,

      Thanks for the input. Here's some more info for you.

      > I've been following your dialogue on the solar sheds and lawnmowers with
      interest.
      > I've talked to black and decker many times over the years about using solar,
      esp.
      > in the context of lawnmowers because I think their unit is basically poorly
      designed.

      Yeah, I don't like the fact that it's *all* plastic and just doesn't seem to
      cut well.
      > I own one also, and don't like the idea of having to store it near an
      electrical outlet,
      > which means in the garage. I'm sure a lot of people with a garden shed
      would like
      > to keep their rechargeable mowers there, after all, that's what they bought
      them for.

      I've been wheeling the battery cabinet into the shed daily after I work on it,
      so I've had the mower in the garage also. But since I'm in the mowing season
      now, I just charge it up after use (about 3 hours), and then leave it parked
      in the garage not plugged in. It doesn't hurt anything to not leave it on
      continuous charge during the summer.

      > I've talked to Dave Shaver in the past, he is a helpful, informative person,
      and
      > knows rechargeable technology. Unfortunately, Black and Decker follows
      mainstream
      > trends, is not interested in solar, and, in fact, builds horribly wasteful
      chargers for
      > their Versa-pak tools and others. Their 12vdc adapter for the Versa-pak
      batteries
      > wastes about 70% of the input power as heat, and is therefore not very solar
      friendly.
      > And as you have already discovered, their mower accepts an AC input, not
      DC,> and is the only wall pak I've ever seen that has an AC output for
      recharging lead
      > acid batteries. This sure make solar more difficult.

      I found the way they built that mower is typical of most electrical equipment
      nowadays. I have the Versapak system too, and it takes DC into the charger
      base, so it should be an easy conversion. My cordless drill charger is the
      same way.

      > There is a simple, less expensive approach for anyone wishing to just
      recharge
      > the mower, as opposed to building the large system James has undertaken.> In
      the Houston area, two 5 watt panels will recharge the mower in a week for
      > most people, the exception being a fully discharged mower and cloudy
      weather.
      > If you remove the top shroud (6 screws) you can gain access to the
      batteries.
      > Tapping into the positive on one and the negative on the other gets you
      around
      > all the battery charging electronics. Tie a simple 24V solar voltage reg
      with
      > temp comp to these terminals and mount it close to the batteries, but under
      the
      > shroud. I would recommend a regulator that is encapsulated, since it is a
      harsh
      > environment under there. Come off the input side of the reg with a polarized
      2
      > conductor SAE connector (think boat trailer) and bring it outside the
      shroud.
      > The diode in the reg should make this a "dead" connector electrically. Wire

      > your two 5 watt panels in series with the mating connector and keep it
      plugged
      > in all the time or the quiescent draw of the regulator will slowly drain the

      > batteries. The whole system should cost less than $200, and is a little more

      > practical than the solar playhouse James is building..

      I actually read an article in Home Power about this exact project being done
      by Ron Knapp. I decided to accomplish the goal of getting the mower recharged
      first, and then work on a stand-alone system later. My resources are limited
      at the moment because I am unemployed, but when that is remedied, I want to
      actually get a second mower, a Toro model, and try it as well. If I build a
      charger, I want it to work on both mowers. I didn't like the economics of
      small solar chargers too much, small panels are typically $10/watt or higher.
      Plus, if I'm going to spend money on panels, I want them charging something
      all the time, mower or no mower. Incidentally, if you're going to use discrete
      panels, you can use 3 smaller ones, a small 3-pin regulator, and feed the
      internal charger on the mower directly. There's a lot of different things that
      can be tried once I get to that point in the project. I did add an external
      connector for direct access to the battery.
      > I'm saying that facetiously because I've given serious thought to building
      a small
      > solar power system that converts a standard garden shed into "Dads
      Playhouse"
      > I've often thought that you could justify it with the intentions that James
      has, then
      > add the small refrigerator, TV, and satellite dish later. We all know that
      most men
      > can never have enough toys to play with, this one happens to have some
      practical
      > uses as well. James, I hope I'm not getting you in trouble right now, if I
      am just
      > hit delete.

      I've always had a number of goals in my head that I wanted to accomplish with
      this project. When I built the shed, that's why I built it with a south facing
      roof and an electrical supply from the house breaker box. I knew that after I
      built a system to power the shed, that power could be fed back to the house
      for backup purposes, especially during a hurricane. I'll be the first to admit
      that this project is really fun, and using solar for real has always been a
      dream of mine.
      > On a serious note, I would caution against building a two tier battery
      enclosure out
      > of wood when using "wet" batteries. Battery acid, spills and even fumes
      will really
      > destroy wood quickly unless it is coated in fiberglass. The insidious thing
      is you can't
      > see it, the wood looks fine, but slowly deteriorates from the inside until
      it will literally
      > crumble in your hands. Rubbermaid makes some pretty tough outdoor plastic
      > cabinets that will work well. I suggest putting the batteries on a concrete
      pad or
      > prefab AC pad for stability. And don't believe the myth about storing
      batteries on
      > concrete, that hasn't been true since WW2.

      The whole cabinet is designed to handle acid. As soon as it dries up enough
      outside to paint, it's getting coated inside and out with epoxy paint and a
      polyurethane sealer. I've tested the combination out on a piece of scrap wood
      and let straight battery acid sit on it for a few days. It was unaffected.
      Plus, I've designed the cabinet so that spills naturally flow to the front,
      and I'm putting in a drain to the outside. From what I've read, it's
      advantageous to be able to occasionally wash the tops of your batteries off
      with water, and the drains will make that possible. I'm using battery caps I
      bought from Northwest Wind and Sun that limit the splash from 40-60%. I've got
      2 small fans in the bottom to push the fumes out. And yes, the batteries on
      concrete thing is indeed a myth. > Please send a photo of your system when it
      is finished, and keep up the creative thinking!I'm working on that. I need to
      get my scanner hooked up.

      James
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