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Thread: 1979 XS750 electric conversion

              
   
   

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  1. #1
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    1979 XS750 electric conversion

    Alright, lets get this thread started.
    I recently acquired the aforementioned XS750
    I will add pictures later this week.

    I have ordered the following parts:
    17" by 6" 12kw rear hub motor from qsmotor (configured for 145kph)
    300a ANT bms with screen.
    Kelly KLS96601-8080I
    A 220v charger for 96v lipo at 20A
    Swingarm from a fazer since my bike stock was shaft drive.

    I already have lying around:
    A pile of matched nissan leaf batteries to make my battery
    The bike itself

    Things I still need to get:
    Brakes for the rear wheel (I'm in contact with some suppliers right now)
    J1772 adapter to feed the charger
    throttle (considering either a domino pot throttle if i can find one, or a cable throttle pot module)
    Dcdc converter (suggestions welcome)
    Main power contactor


    I did some looking about but I could not find any mention of anyone using this motor.
    https://www.qsmotor.com/product/17-inch-12kw-hub-motor/

    I plan to document my entire build process thoroughly with lots of pictures and data.
    There is a local place that is willing to let me use their dyno too when I get it put together.

    For variable regen, I plan to use some kind of strain gauge on the rear foot brake. I havent figured out the details yet, but I am sure emulating the potentiometer input to the controller for that with a microcontroller based on the output of the strain gauge should not be too hard.

    I don't expect this to be a drag strip monster, but having some actual data out there should be informative.



    Any other suggestions are welcome too.

    Here are some photos of what I have so far:
    This is how it looked the day I bought it:
    TuojwY2-min.jpg

    Then I started stripping things down:
    TK7q3Uj-min.jpg

    Here I tried fitting one of my leaf cells for reference to see if they would fit, and what orientation might be best:
    nU6zliE-min.jpg
    vq8MmKo-min.jpg

    More recently, I assembled the pack itself.
    At 96v nominal, I estimate that the pack should be around 4.3Kwh. I plan to build another pack at some point later with LG chem cells that would be around 11kwh, but those cells are expensive and I already have these, so...
    puJreUw-min.jpg

    Here is a cardboard box made to the dimensions of the aforementioned battery module for scale reference.
    I need to build an enclosing box to hold this and some of the other electronics in.
    IMG_20200706_153354_compress95.jpg
    IMG_20200706_153410_compress48.jpg

    And lastly, here is a picture of that fazer swingarm I ordered:
    $_57.jpg

    I hope it fits. Some other conversions from shaft to chain for the XS750 used this swingarm, so fingers crossed that it will not require much modification.
    We'll see. It should get here pretty quick, it is only going across town.
    Last edited by biothundernxt; 06 July 2020 at 2359. Reason: Adding images

  2. #2
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    Looks like a nice easy fitout dude - great job so far - and well done on the parts selection.
    That motor marries pretty much perfectly with those modules and that controller in terms of what they can each draw and source respectively.

    WRT the strain gauge notion - have you worked with them before? They can be a real PITA at the best of times.
    I'd be more inclined to put a pressure sensor onto the brake line. There's no shortage of vendors out there doing custom lines - all you need is a split line terminated with the appropriate fitting.
    Far more reliable measurement.

    The other route you could go would be similar to the Vectrix approach - they use a throttle which goes both directions. Roll back for acceleration, forward to deceleration. Added bonus is that the latter allows it to reverse as well.

    Whatever way you go, I'd stay well clear of strain gauges unless you're well accustomed to working with them (I have quite a few hard yards with the things in custom applications) - they'll only break your heart.

    I don't see any mention of a BMS in there - they aren't a must, but if you're not using them then you'll want to leave yourself with the ability to easily check and balance manually.
    Doesn't have to be anything fancy, but you will want to have something. Those leaf modules are unbelievable good at staying in balance, but you'll still get variations.

  3. #3
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    I can understand why the engine is missing from that XS750 chassis. As I recall, the 750's engines were not one of its strong points from a reliability standpoint.
    Richard - Current bikes: 2018 16.6 kWh Zero S, 2016 BMW R1200RS, 2011 Royal Enfield 500, 2009 BMW F650GS, 2005 Triumph T-100 Bonneville, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior.

  4. #4
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    Quote Originally Posted by Richard230 View Post
    I can understand why the engine is missing from that XS750 chassis. As I recall, the 750's engines were not one of its strong points from a reliability standpoint.
    It was actually in really great shape until the guy who owned it before me got his hands on it. It needed some routine maintenance, so he took it to a mechanic, and the mechanic suggested a couple things could stand to be rebuilt. He asked if he wanted him to get started so he said sure, but after the mechanic got done taking the top end apart, they started talking about money and the guy balked and just asked for the parts back. So then they sat in a box outside for over a year.
    Needless to say everything in the box rusted.

  5. #5
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    I got all excited when I thought someone was going to use an inline motor and a shaft drive. I was thinking centralized motor and a short belt drive to the drive shaft. Bit disappointed now.
    Good chassis for a conversion though. Good and strong in the right places. Old school suspension though.

  6. #6
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    I am not set on using a strain gauge.
    My only real experience with them was with auto leveling 3d printers... which never really worked very well anyway.
    I mostly just want to retain the foot brake and the feel.
    I might go with keeping the foot brake stock and adding a second throttle for variable regen.

    I did get a BMS, I just forgot to post it on there.
    I wanted to get an Orion 2, and likely will for my second build, but the expense was too much to justify for this build.
    I am using a 300A rated ant bms with a screen and bluetooth.
    I've heard good and bad things about them, but i figured it would be better than no BMS, and it was about 1/10 the price of the orion 2.


    My first inclination was to use the shaft. I could not find a motor with enough oomph that would fit without some serious modification to either the frame, or the shaft. I mocked up the ME1616 and the AC-20 but nothing would fit to the input of the shaft.
    I considered mounting the motor transversely, and using the AC-20, but I had concerns with the torque leaning the bike over in corners.

    I plan to do another build after this one is complete, but it will be much more long term, and very expensive, so I wanted to build this to get me riding in the mean time.

  7. #7
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    Quote Originally Posted by biothundernxt View Post
    I might go with keeping the foot brake stock and adding a second throttle for variable regen.
    In case it's useful, the Vectrix throttle is available here:
    http://www.shop.vectrixparts.com/thr...-and-grip.html

    Rolls about 90degree back for acceleration and about 30degrees forward for deceleration/regen in normal use.
    Output is the standard 0-5V range so it's ostensibly something like regen from 0-1.5v and motoring thereafter.

  8. #8
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    Fascinating. Thanks. Definitely more than I want to spend on a throttle, but I will keep it in mind if I cannot find anything else that will work. I would have to do some complicated stuff to get it to work with my kelly controller though.

  9. #9
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    Does anyone know how hard it is to open these motors?
    I was already considering opening it to apply some statoraid, but my communications with the QSMOTOR factory are making me very curious to see inside this motor.

    They are claiming that the motor windings are 6T, but that there are two coils in each location where there would be one coil on the 8KW motors. They are calling it "35x666 hang on both side design, not as normal 8KW motor"

  10. #10
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    Thanks for posting your project, really nice.
    Was precisely looking for a hub motor at 10+kw for making the conversion simpler and this qsmotor seems like a good solution.

    I'm also very interested on how you solve the rear brake function, keep us updated!

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