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Thread: More amps or more Volts?

              
   
   
  1. #1
    Old EV Racer EVcycle's Avatar
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    More amps or more Volts?

    Hello all.

    I am stepping into the world of PMAC motors. (New for me)

    The Voltage pack is either 67V at 700 amps max or 130v at 350 amps.

    The motor will do 6000 rpm, 100V / 600 amps ( can do 144v 700 amps for short bursts).

    For drag racing would the 67V at 700 amps work better? (1/8 mile)

    I am asking as I limited on controllers that will work for this application.

    Thanks!
    EV Ed
    Never let being a responsible adult get in the way of passion and curiosity.
    Juiced Drag Racing
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    Ev album 2456, 2458, 2457, 2681, 3456, 3630

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    Senior Member Stevo's Avatar
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    I'm thinking motor rpm is controlled by voltage, so wouldn't higher voltages be better for speed's sake?
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
    Current builds: http://elmoto.net/showthread.php?t=4354

  3. #3
    Empulse R #24 frodus's Avatar
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    What motor is it?

    Do you have controller already?


    Usually the higher voltage, the higher it can go in the RPM range. But the higher current, the higher torque.

  4. #4
    Old EV Racer EVcycle's Avatar
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    ME1507 PMAC Brushless Motor - no controller yet

    Hey Travis, That is where I was going with it. 660 feet of go go go racing.

    I would like to have 300V at 1000 amps, but it is a small bike so there are battery limitations (and my wallet)
    EV Ed
    Never let being a responsible adult get in the way of passion and curiosity.
    Juiced Drag Racing
    Motenergy.com
    Ev album 2456, 2458, 2457, 2681, 3456, 3630

  5. #5
    Empulse R #24 frodus's Avatar
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    I don't know of other controllers that are tuned with that motor besides the Sevcon Gen4 series. The Size 6 is 550A 2 minute, 660A peak for 10seconds. That ought to do well for 660ft! That's at up to 116VDC. 130 is a tad high, and 67V is a tad low. I think you'd hit a wall with speed at some point. If you could aim for higher than 72V... and maybe 500A?

    (Shameless plug, my company sells the Sevcon Gen4 controller, harness, contactor, programming cable and can program for the 1507)

  6. #6
    Old EV Racer EVcycle's Avatar
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    I have looked at that controller (on your site), but I need to be able to program on the fly as track as conditions and rider confidence (Tammy) progresses.

    Kelly has one too. (They sent me the info.)

    I would have gone with a brushed DC motor, but we have burned up a brush set or two so it is time to go to the dark side....hee hee
    Not many that I have seen ( still checking the internet) have done the drag racing with a AC motor, but the bike is light weight so it should work.

    If nothing else we can do some good damage in the bracket racing side of things.

    On a side note, I could get to pack to 116V 500 amps, but I would have to do some swapping around with the Cafe racer...
    Last edited by EVcycle; 20 April 2018 at 1726.
    EV Ed
    Never let being a responsible adult get in the way of passion and curiosity.
    Juiced Drag Racing
    Motenergy.com
    Ev album 2456, 2458, 2457, 2681, 3456, 3630

  7. #7
    Empulse R #24 frodus's Avatar
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    I'd aim for 100V and 500-550A if you can. Nice sweet spot with this motor/controller combo.

    The DVT Programming kit can allow some parameter changes on the fly easily.

  8. #8
    Old EV Racer EVcycle's Avatar
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    Thanks Travis.

    We are looking at all the options....

    So far yours is the best...
    Last edited by EVcycle; 20 April 2018 at 1736.
    EV Ed
    Never let being a responsible adult get in the way of passion and curiosity.
    Juiced Drag Racing
    Motenergy.com
    Ev album 2456, 2458, 2457, 2681, 3456, 3630

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    Current == Crank Torque
    Voltage == Crank RPM

    High voltage means lower currents for any given power level, which means less heating and better efficiency; it also means higher RPM so shorter gearing which means less mechanical strain on the low speed components.
    So 'money no object' it's HV everytime - the caveat to that is, as suggested, HV kit is eye-wateringly expensive.

    High current means greater thermal losses, greater mechanical wear, and bigger power components; but makes for a *vastly* cheaper setup.

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