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Basic DC

  1. Mar 3, 2009 #1
    Hello All-

    COuld someone please give me a primer on DC as it pertains to voltage, amperage and wattage. Specifically, if I have a motor that i need to run at very low RPM (50 -150), how does the motor compare across a 12v system vs. a 24, 48 or even 60v system. Do 60v systems run more efficiently than 12v systems? Pound for pound (or mass for mass) will a 60v battery of roughly equal size as a 12v battery run a motor longer ?
    Let me paint the broad picture-
    my project is to build a frame that will weigh 2000lbs gross, (frame and cargo), and have it crawl at 1.5-3mph. I have found wheel/hub motors that by spec sheet can do the job(enough nm or ft/lbs of torque), but they come in a w-i-d-e variety of voltage platforms, again 12v-60v. Needing to run this cargo platform continuously for approx. 90 minutes at a constant speed,(between 1.5-3mph), which is a better voltage platform to run on 12,24,36,48,60v???
    If amp draw is constant across voltage platforms, which would run the motor longer?

    I guess to sum up - Why would i want to use a higher voltage platform?

    Any help or direction would be hugley appreciated .

    by the way here's a great energy conversion link i found @ www.1728.com/energy[/URL]

    Thanks to all,
    Last edited by a moderator: Apr 24, 2017
  2. jcsd
  3. Mar 3, 2009 #2


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    Staff: Mentor

    Last edited by a moderator: Apr 24, 2017
  4. Mar 3, 2009 #3
    Thanks berkeman-
    It's www.1728.com/energy.htm, forgot the .htm part.

    The crawler will be self powered with an on board battery. I'm assuming if an electric forklift or pallet jack can run all day, then I should be able to get 90 minutes with some sort of industrial, off-the-shelf battery supply. As far as surface goes smooth pavement or concrete will be what it is running on. thanks for the input on the higher voltage being more efficient, similar to 110 vs 220 in the AC world i guess.

    If the efficiencies are only minimal, would i be better served using a lower voltage platform, either 12v or 24v, that would have more readily accessible parts and accessories?
  5. Mar 4, 2009 #4


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    Staff: Mentor

    Absolutely. The efficiency differences should be small, so yes, pick a system voltage that gives you a good range of parts to choose from.
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