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General --Battery Size Question---LED Light install on a Push Mower

Discussion in 'Off Topic' started by Mikestony, Sep 16, 2016.

  1. Mikestony

    Mikestony ~30% Carbon Black ±
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    Odd subject for an Android forum eh? :D But hey, it's the Lounge to talk about anything right? :D :D

    Anyhow, with daylight decreasing now, I am getting home when it gets dark.
    That leaves only the weekend (Saturday afternoons and Sundays) to do mowing. If it doesn't rain :(

    Now, I did some thinking and some brief researching and want to install an LED light on my push mower (21 inch, manual start) with a small battery to power it.

    From start to finish, mowing my entire lawn, takes me about 2-1/2 hours, so I'd like the battery to provide the power needed for the time needed. After which I will recharge it until the next time.

    That being said, I picked out the LED light to mount on the front of the mower:
    72 watt
    [​IMG]
    https://www.amazon.com/dp/B00WE46ZW...lid=3AH6AANV55RZQ&coliid=I1KTV69CYLRO9M&psc=1


    and to power it, what battery do you recommend?
    I need something small that I can mount on the mower and easily remove for recharge.

    I was thinking about this one:
    [​IMG]
    https://www.amazon.com/dp/B003S1RQ2...lid=3AH6AANV55RZQ&coliid=I37U2QKIRK89U2&psc=1

    7 Ah/20 HR <<<------- what exactly does that mean? It will provide 1 amp of power for 7 hours or for 20 hours?

    Being the light is 72 watts, how long would that battery be able to power it? Do I need a larger Amp Hour rated battery?

    How many amps will that light draw per hour?


    Based on this, the light will draw 6 amps. o.k....6 amps per hour????
    [​IMG]
    http://www.sengpielaudio.com/FormulaWheel-ElectricalEngineering.htm



    My mind is fried (pun intended) trying to figure this out.


    Many thanks for any input :D
     

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  2. Dngrsone

    Dngrsone Android Expert
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    It looks like it provides up to 7 amps for up to twenty hours. That would be 4 watt/hours.

    The math is thus: 12v times 7a equals 84w divided by 20h equals 4.02wh

    That is off the top of my head, so if that is wrong, then I am totally going to blame it on my age, which is in the vicinity of L.
     
    #2 Dngrsone, Sep 16, 2016
    Last edited: Sep 16, 2016
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  3. Mikestony

    Mikestony ~30% Carbon Black ±
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    watt/hours? :thinking:

    Reading this excerpt: (emphasis mine)
    - See more at: https://www.batterystuff.com/kb/art...0-amp-hr-rate-mean-.html#sthash.jPV837rB.dpuf


    Let's replace my battery of choice's specs:
    7AH @20 hours= .35 amp load for that 20 hours.

    Put those numbers into the formula:
    [​IMG]
    Electric Power P watts
    [​IMG]

    Amperage I amps
    Voltage V volt

    75 watts (lamp draw) , .35 amps (for 20 hours) = I need a 214.2857142857143 volt battery??????
    Obviously that is not right and I'm an idiot :(
     
  4. rootabaga

    rootabaga Android Expert
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    I'm baffled. The halogen headlights in my car only draw 55 watts each and they're good at night on the freeway.

    I'm guessing you don't push the mower that quickly.

    Why such a high wattage? Why not something lower? You could probably use a couple of L-ion batteries to power it and it won't cost much to recharge them.
     
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  5. Mikestony

    Mikestony ~30% Carbon Black ±
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    I push it at a normal walking pace (I have a large yard) (yeah, I know, get a rider mower....I need my exercise :p)

    Why such a high wattage? Honestly, not sure lol....I just don't want to get something underpowered and be dissatisfied with it. :D

    What about punching my numbers into this calculator?
    https://www.batterystuff.com/kb/tools/calculator-sizing-a-battery-to-a-load.html
    I'd need a 48Ahr battery?

    Am I being kinda silly wanting a 75 watt LED light? Be honest, I'm a LED light newb :D
     
  6. jhtalisman

    jhtalisman Android Enthusiast
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    Have you thought about some solar powered lights?
     
  7. Mikestony

    Mikestony ~30% Carbon Black ±
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    lol, what? :D
     
  8. Dngrsone

    Dngrsone Android Expert
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    They're perfect for nighttime use...
     
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  9. jhtalisman

    jhtalisman Android Enthusiast
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    No external battery required. You can remove them from the mower to charge during the day. Just have to figure out a way to mount to mower.

    Or maybe an LED headlamp?
     
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  10. basic 101 user

    basic 101 user Android Enthusiast
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    I love rolling this stuff around, (and might someday have something truly meaningful to say)......But today isn't your lucky day.:p

    As ever, I'm mostly asking here, not telling......(Please notice I seldom weigh in on matters Android, Linux, code, etc.)..... I'm in the lounge for a reason.;) (And I tell you most definitely...... I'll definitely tell you, on those rare occasions when I'm definitely telling you)!:mad: :p;)

    Random blah blah.......I do get that "volt, watt, and amp" all have scientific, "definite definitions"......But I feel like my understanding of them has been corrupted over time by "marketing". I'm watching some remodeling go on here, and six light fixtures are being installed in the ceiling. Each a 12 watt fixture.:thinking: "Don't worry, each one is (basically) a 75 watt fixture", they tell me. Okay..... true power consumption, compared to my grey haired sense of "how much light" from "old school" incandescent bulbs.....leaves me scratching my head, and the math doesn't ever work like I think it should.
    I offer no proof, but my gut tells me that the lamp shown above is likely enough firepower to do what you want, and that battery has way more capacity than what is required to get you to 4:30 AM.....At which point your neighbors should be even more concerned about you, than mine are about me.:thinking:;)
    Battery capacity is one thing, peak momentary output is another.....And one is sexier and more marketable than the other; I suspect you'll be OK on both counts. It may not be an apples to apples comparison, but I bet it's close......A similar gel cell Varley "Red Top-25" is roughly comparable, and commonly fitted to Formula Fords, sports 2000's, etc. If you want to hear serious blah, blah, I dare you to ask me about torque vs. horsepower vs. actual driveability.....And what really matters ( satisfies on the street, and wins races on the track).

    James Watt himself, who defined the standard, would likely be the first to tell you...(Paraphrasing wildly), "The average horse can routinely make 25 horsepower"

    My question to the room, and loosely related is: How come any given (18v.) battery pack will run my (generic) Sawzall (TM) all day long, doing demolition work......But slap that same pack into the job-site AM/FM radio bundled with the tools, fully charged up........ And it croaks in three hours, every time?:eek:
    [/Blah, blah]
     
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  11. Dngrsone

    Dngrsone Android Expert
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    Things really started going downhill when CFL bulbs came out to replace incandescents; a "60w equivalent" CFL might only draw 13w, but you can't market it as a thirteen watt bulb, you gotta call it sixty.

    Then there is the similar model right next to it, which should pressure the exact same, according to the package, but is an entirely different color...

    Warm white, cool white, lumens, brilliance, wth? Suddenly the consumer needs a physics lesson just to buy a damn light bulb.
     
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  12. Mikestony

    Mikestony ~30% Carbon Black ±
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    Yah :D
    I even put the LED bulbs in my car's headlamps....wow, what a difference! Nice though :)
     
  13. Dngrsone

    Dngrsone Android Expert
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    Then, when you work in radio frequencies and such, there are different kinds of power: peak, true, effective power are all different numbers.
     
  14. rootabaga

    rootabaga Android Expert
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    So a bit closer to meeting needs rather than attracting low-flying aircraft looking for an airport... ;)

    What about just a great quality L-ion powered flashlight with zoom? I have a couple of these, it throws a beam plenty wide for mowing. It comes with a charger and two of the larger L-ion batteries, and I'd bet one battery would last the time it takes you to mow the grass, especially if it turns out you can use it on the lower-power mode. Creative use of zip-ties should affix it to the mower handle.

    https://www.amazon.com/UltraFire-XM-L-T6-Flashlight-Rechargeable/dp/B00MPCVLFE

    I'd vote against a regular LED headlamp. They're designed really for closer-up work (great for working on your car for example) and are lower-power, so it's probably not practical. You could probably use a spelunking headlamp since some of those are designed for cave exploration and throw a tighter beam. Some of those have an external battery pack, too.

    I found this one at Amazon, also with batteries and a charger, it really might be ideal. The lumen count is based on all three bulbs lit, so if you can use just the center you'll see better battery life. This might be really practical (since it aims where you look) so long as you don't mind the sweat under the strap. ;)

    https://www.amazon.com/5000Lumen-KissAir-Flashlight-Headlight-Rechargeable/dp/B018ZG6NV0

    Good luck.
     
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  15. Mikestony

    Mikestony ~30% Carbon Black ±
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    ooo, I like that flashlight idea!! It appears it has a clip on it to affix it to the bill of my ball cap!
    Hmmmm, that may be something worth trying! Thanks!! :D

    Edit: I may go with the shorter/lighter version, as the one you linked weighs about a pound.
    https://www.amazon.com/dp/B00BH0AOGC/ref=psdc_2445457011_t3_B00MPCVLFE
     
    #15 Mikestony, Sep 19, 2016
    Last edited: Sep 19, 2016

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