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Electric racing -- Custom 4WD Electric Race Car Advice Please

  1. Jul 6, 2018 #1
    [Mentor's note: two threads on the same topic have been merged]
    I live here in Stephenville, TX and currently going to Tarleton for Civil engineering. A bit rusty and new to electrical components.

    But anyways, here in town lawnmower racing is kind of a big event. Many of us have 600cc crotch rocket motors on them, and they are very fast. I have one currently built I’ve been racing for years. Now i have been trying to convince myself to build an 4x4 model so I get better traction taking off. I have been wanting to build a electric driven one for a while and have been doing a ton of research until I found this site.

    Now I’m not for sure what all I would need to start this build, and I have a ton of questions. As in what size motor and phase motor to use, what electric speed controller would be best, do I need a certain battery or will the yellow top optimas be okay to use?

    Basically this is what I have so far. A 15hp 3 phase motor, 1735 rpm, 60 hz. Ill post a pic of it below. Now will this be enough power to move me in a light frame at a fast enough speed? We usually go about 100-125 ft drag strip on dirt. So I would be probably putting the motor in the middle with two sprockets and a chain to the front and back drive shaft. But basically what I’m asking is where would I start?

    1. Can I even use this motor with car battery’s.

    2. Is 15hp enough to move at a considerable speed?.

    3. What kind (if any) converters, resisters, ie. other parts would you think i would need to assemble to make something like this. Any advise is welcome!!!
     
    Last edited by a moderator: Jul 7, 2018
  2. jcsd
  3. Jul 6, 2018 #2
    I live here in Stephenville, TX and currently going to Tarleton for Civil engineering. A bit rusty and new to electrical components. But anyways, here in town lawnmower racing is kind of a big event. Many of us have 600cc crotch rocket motors on them, and they are very fast. I have one currently built I’ve been racing for years. Now i have been trying to convince myself to build an 4x4 model so I get better traction taking off. I have been wanting to build a electric driven one for a while and have been doing a ton of research until I found this site. Now I’m not for sure what all I would need to start this build, and I have a ton of questions. As in what size motor and phase motor to use, what electric speed controller would be best, do I need a certain battery or will the yellow top optimas be okay to use? Basically this is what I have so far. A 15hp 3 phase motor, 1735 rpm, 60 hz. Ill post a pic of it below. Now will this be enough power to move me in a light frame at a fast enough speed? We usually go about 100-125 ft drag strip on dirt. So I would be probably putting the motor in the middle with two sprockets and a chain to the front and back drive shaft. But basically what I’m asking is where would I start? 1. Can I even use this motor with car battery’s. 2. Is 15hp enough to move at a considerable speed?. 3. What kind (if any) converters, resisters, ie. other parts would you think i would need to assemble to make something like this. Any advise is welcome!!!
     
  4. Jul 6, 2018 #3
    Ive posted a photo here of the specs of motor. I apologize if i am in the wrong forum.
     

    Attached Files:

  5. Jul 6, 2018 #4
    I guess that it would help to take a look at the best performing electric cars which exist.
    Then see if that tech can be scaled down appropriately for a local competition.
    https://edgylabs.com/top-10-fastest-electric-cars-on-the-planet
    15hp really isn't that much, and rocket assist works the same way whatever your primary engine is.
     
  6. Jul 6, 2018 #5
    Okay. Yeah that 15 hp motor is super heavy, I wasn’t sure if it would have enough power realistically to move fast enough. But with the power to weight ratio of what its going on, I know I wont need much.
     
  7. Jul 6, 2018 #6
    IMHO, the three-phase inverter you'll need for that 60 Hz motor is non-trivial. Also, the starting torque may not suffice. Please step back and have another think.
     
  8. Jul 6, 2018 #7

    Tom.G

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    A quick Google search shows a 500cc at 48HP.
    The motor nameplate you posted shows 1HP.
    Looks like you will be like that guy in the Circus parade, following behind the elephants with a shovel and wheelbarrow. :cry:

    Sorry
     
    Last edited: Jul 7, 2018
  9. Jul 7, 2018 #8
    It’s kinda hard to see but it’s actualy 10 hp. The motor is super heavy. I’ve been told on other forums and other people that really the hp rating on an electric motor isn’t comparable to hp out of an gas motor. And that it’s all about how much power you can supply. I’ve seen people use 30 hp motors to power small 3000 lb cars. So I do believe this 10 go motor is enough but just wasn’t sure if two-three batteries would suffice.
     
  10. Jul 8, 2018 #9
    You still have to drive it with 60 Hz three-phase. IMHO, that seriously limits its potential starting torque.
     
  11. Jul 8, 2018 #10

    jim hardy

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    I suspect you'd do better with a DC motor. I would peruse junkyards for the starter motor from a big diesel or aircraft engine.
    My favorite local metal recycling yard recently had some DC motors from military transports , about the size of a gallon jug. Weight i'd estimate maybe forty pounds. Nameplate said 1000 amps at 28 volts, that'd be 37hp input .

    Lawnmower Drag Racing ? You're my kind of folks.

    old jim
     
  12. Jul 9, 2018 #11
    1) No, this is an AC motor, batteries are DC

    2) Depends on the weight and how much friction, if you are up against 600cc bike engines which have what 100-130Hp? then 15Hp is not much. Now one thing with electric motors is they can be over driven for short periods, so the 15Hp machine can maybe give you a 30-45Hp short burst. But the issue is the inverter needed, and its an induction machine so they have kind of crappy starting torque plus no doubt you'll need to make probably 208V 3phase? which is on its own not trivial.

    3) I don't know how much $$ you have to burn on this, but I think the easiest would be to get brushed DC machines, for example golf cart motors and DIY EV conversion motors would work well (search for Warp 9 brushed machine and you'll get an idea). If I were doing this I'd look at 4 identical golf car motors, one for each wheel, then a big 2 step contactor (big switch) that connects bats in parallel for the first acceleration (low voltage lots of current) then once up to some speed click them into series (more volts less current).

    Next step up would be permanent magnet brushless, but thats a step up in complexity as well.
     
  13. Jul 11, 2018 #12

    dlgoff

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    :oldsurprised: You did get some of these didn't you? :oldwink:
     
  14. Jul 11, 2018 #13

    anorlunda

    Staff: Mentor

    I don't know your budget or constraints either. But I see many BLDC motors marketed for golf carts and for motorcycle conversion. They use low voltage DC. Most of them come with built-in controllers that handle the complexity of flexible electronic control. I see them on alibaba, amazon, ebay and similar sites in a variety of powers, voltages and details.
     
  15. Jul 11, 2018 #14

    jim hardy

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    Pretty sure i got two. :smile:

    There was another clean GM653 turbo diesel there last week with two giant hydraulic pumps, cane i believe from some sort of aircraft tow vehicle it had one of those DC nachines.
     
  16. Jul 11, 2018 #15

    Tom.G

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    And to what use will they be put?
     
  17. Jul 12, 2018 #16

    jim hardy

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    I was thinking perhaps a motor driven welder,
    or a source for preposterous amounts of DC current. (Dr D got me interested in Ampere's law,,,)
     
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