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Semi Owner needs help sizing electric motor

Discussion in 'Semi' started by Trucker, May 27, 2019.

  1. Trucker

    Trucker New Member

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    Hey gentlemen, I need someone who knows quite a bit about electric motors. I'm not waiting any longer to pull the trigger. I will be pulling a dry van 53' trailer both combining weight of only 70,000 or less. What size/type of motor should I get...I have been looking at 600-800 hp ac induction motors. Any help would be great, thanks guys.
     
  2. scottm

    scottm Version 9 software sufferer

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    What are you doing for batteries?
     
  3. Trucker

    Trucker New Member

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    I've got that part figured out, thanks sir.
     
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  4. scottm

    scottm Version 9 software sufferer

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    #4 scottm, May 29, 2019
    Last edited: May 29, 2019
  5. Trucker

    Trucker New Member

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  6. Trucker

    Trucker New Member

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    This was helpful...and your right "If" I go with 2 motors on both axles they do need to be short, and the weight looks great...contrary to belief but their isn't much room between tires
     
  7. scottm

    scottm Version 9 software sufferer

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    #7 scottm, May 29, 2019
    Last edited: May 29, 2019
    The link shows dual stack motors. Drive output shaft on one end only.

    What about 1 of these per axle, but driving opposite sides of the truck?

    Or could that create a situation when tilting on some uneven terrain where no power reaches the ground ..? I'm trying to imagine how different wheels lift while driving through ditches on a diagonal.

    Or, don't go with dual stacked, get 4 motors - one for each rear wheel on the truck.

    How much space do you have between the inner wheel rim to the opposite side's inner wheel rim?
     
  8. gnuarm

    gnuarm Model X 100 with 72 kW chargers

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    That's were the 70,000 lbs comes from. ;)
     
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  9. linkster

    linkster Active Member

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    Gosh, do you grab 4 rear M3 motors from an auto recycler and duplicate the 5 -10 year delayed (since amazing Jerome was yanked away to fix the M3 assembly line from imploding) Tesla semi layout with 1/wheel. Mr. Twitter claims (lol) the motors will rock for a 1M mile service life.
     
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  10. Saghost

    Saghost Well-Known Member

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    The problem with this approach is the gearing, or lack thereof. Having taken out the transmission and differential, you're left with the motor spinning at wheel speed - meaning something like 500 rpm on the freeway, with no torque multiplication.

    You want at least 9:1 gearing, and ideally more like 15 or 20:1, to get the motor into useful operating range and get the torque up to something viable for pulling loads.

    A stacked pair of planetary sets might be sufficient, but that's not generally an off the shelf option that I've seen.

    The other obvious solution is to keep the differential and transmission and put the motor where the engine goes. There's some wasted weight in that, since you don't need all of the gearing options the transmission gives, but it can work.
     
  11. scottm

    scottm Version 9 software sufferer

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    I'm afraid I don't follow you. What are you saying?
     
  12. scottm

    scottm Version 9 software sufferer

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  13. Ulmo

    Ulmo Active Member

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    #13 Ulmo, Jun 4, 2019
    Last edited: Jun 4, 2019
    To answer your question poorly, I am less than a novice in that field, but we know, for instance, that four Model 3 motors are more than enough to pull a fully loaded semi, because that's precisely what the Tesla Semi uses. I'm sorry I can't give you any more direct help. But I can give some indirect help in spades! I have an idea of who might have a little bit of knowledge in motors:


    I was surprised with the amount of info gathered by these two gentlemen, but I have no idea if they'd be willing to give you the proper info: I hope you know about these gentlemen, but just in case you don't, here they are, but I don't know how good they are for your precise needs.

    First, wk057's shop, who had some of the earliest Tesla conversion systems on the market, and he is quite good at what he does, but I believe this is a hobby for him, so if anything, start with EV West below:

    057 Technology

    ---

    Second, EV West's shop, who may have come later to Tesla conversions, but has been doing electric conversions for decades (mostly on Volkswagons, though), and has a business built around this I believe:

    https://evwest.com/

    I especially like this product they offer with respect to what you're looking into; review the below videos for a bit of background on them before you jingle them:

    Technical Support & Counseling - 15 Minutes, EV West - Electric Vehicle Parts, Components, EVSE Charging Stations, Electric Car Conversion Kits

    I got that link from this interview of them by yet another guy starting his own Tesla-only shop:


    Another video showcasing some more of EVWest's work:


    I found EV West's own YouTube channel; this video was in 2013, and that thing looks good for a semi (300 hp - 400 hp and 1200 ft lb of torque?), and I think this is before wk057 even started tinkering, so these guys seem like a good starting point:


    ---

    There are others, but I'm not as familiar with them. Jehu also did a VW conversion, for instance, but he's more into Lithium batteries in general, and does a lot of things with them, including his one VW conversion; you said you already have your battery sorted. jehugarcia

    ---

    While looking for another one I've seen on YouTube, I found some random ones I've seen before. This guy Jack Rickard is well educated, and methodical, so he is slow but precise:


    ---

    I've never seen these European guys before:


    ---

    I did not find the video I saw about a company selling a private motor controller for Tesla motors. However, I felt like I got on the right track when I hit "tesla inverter" in youtube and searched, since a lot of similar content came up to the controller I was looking for.

    ---

    Ok, I hope I didn't slow you down by posting all those tubes!!!

    ---

    P.S., I think you need to look at both HP and torque. You need the torque for your weight (you need to research that since I don't fully understand it right now). You need the HP to get up hills, for instance. Our Hwy 17 here in Santa Cruz & Santa Clara Counties in California puts a lot of broken down semi trucks on the side of the road because the people who sent them out were cheap or their mapping software didn't take into account elevation (stupid!); I see a broken down semi truck on 17 every day, and every single one of them looks like a cheap weak thing with a surprised driver that's never seen a hill in his life, not a regular truck that goes across every day and has no problem because it's spec'd right and the bloody trucker companies actually know they're going across a hill! (I mean, didn't those cheap companies even try LA's Grapevine?! I mean duh! We have 3 mountain ranges in California, and yet they seem to think they can get away with weak trucks here. I have no idea why.) Here's a blurb I found just by searching the web:

    "Torque to Spare​

    How much power does it take to move a fully loaded semi and trailer? A Detroit Diesel DD15 14.8-liter inline six-cylinder engine weighs 2880 pounds, or 345 pounds more than a Mini Cooper. This colossal powerplant makes up to 560 hp and 1850 lb-ft of torque, and at just 1200 rpm the engine produces more than 1500 lb-ft of torque. Most turbocharged diesel engines put out between 1200 and 2050 lb-ft to keep all that weight moving."​

    from 10 Things You Didn't Know About Semi Trucks - Wheaten Financial

    and How much horsepower does a semi truck have

    Here's some fun stuff on trains (notice that some of the best info on hill grades comes from those still working in the field, or from books from the steam era; math is math, regardless of tech or age of our grandfather):

    How does one freight engine pull 100+ train cars that weight more than a ton each? : askscience
     

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