DC motorized Cart help

Discussion in 'The Projects Forum' started by gwh68, May 18, 2009.

  1. gwh68

    Thread Starter New Member

    May 18, 2009
    2
    0
    Hello all,
    Although I PM'd a senior member who I think may be able to help me with this, I thought I'd throw it out for everyone in hopes of finding someone with the expertise to help me.

    Here's what I'm trying to do:
    I have a two wheeled cart that I take into the forest. I'd like to add a motor to it (must be electric) to help with moving the load on it down the trail. The load probably wouldn't exceed 200lbs + the weight of the cart (so 225 total) and I doubt I'd hit more than 15% of incline. I also don't need to go faster than 2-3 MPH, torque and hill climbing capability is much more important than speed. I'd also like to be able to maximize battery life as much as possible.

    I'm considering installing a wheelchair gearbox motor but I don't know if there is an equation I should be considering regarding the size/voltage/amperage of the motors and battery system.


    Thank you SO MUCH for any help!
    Brian
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    395
    Take a look at All Electronics ,motors & rotating things. I like Cat# DCM-2445, has gear reduction and about right power, 450W @ 24V DC. Could use some more mechanical speed reduction, with its 9 tooth chain sprocket, use an 18 tooth gear for 2:1 & 2:1 or 3:1 belt driven pulley. Can drive one wheel, or both; or better a jack shaft driven by 18 tooth spk. driving two 4 in v pulleys with 8 in or 12 in v pulleys mounted to wheels. Need a means to adjust belt tension to form a semblance of a differential. Final speed control via PWM control on handle. Two 12V batteries in front of wagon?
     
  3. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    I suggest a 24V DC series wound motor.
    I am saying 24V because it will require less current than a 12V to output the same power and your battery will last longer (if the 24V battery has the same Ah as the 12V battery).

    Series wound motors have the property to increase the output torque in proportion to the square of the current drawn (of course the speed reduces). Thus, at slopes the motor will provide more torque and run slower.

    The wattage of the motor depends on the torque and speed required by the cart to carry its maximum load possible.
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    395
    With 550 rpm motor, 2:1 & 3:1 speed reduction I came up with 5 mph @ 24V & 20. in wheels. With no extra speed control could use 12V for comfortable walking speed. Do you have any prelim. drawings for us?
     
  5. gwh68

    Thread Starter New Member

    May 18, 2009
    2
    0
    Hey Bernard,
    I found this motor too, but it's 36V and 600 amps.

    I'm much more concerned about it being underpowered than overpowered. It would be a little more, but I'm thinking about this:
    http://www.monsterscooterparts.com/...bracket-10-tooth-40-chain-sprocket-1020z.html

    Plus three deep cycle batteries wired in series:
    http://www.batteryspec.com/cgi-bin/cart.cgi?action=link&product=217&uid=2101

    It's going to cost more, but I'm wondering if it would be better suited.
    Thoughts?

    P.S. A wound motor would be great, but I don't think I can afford one!
     
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    395
    Going to build a car? Maybe you ment 600W not amps. Looks like you have every thing , motor, universal controller,& batteries. Put on a steerable third wheel & a seat & go for a ride. Wish you had a differential, HELP!
     
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