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Thread: Hi, I want to build an EV motorcycle for commuting.

              
   
   
  1. #1
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    Hi, I want to build an EV motorcycle for commuting.

    Hi Everyone,

    I have been thinking about building an electric motorcycle to commute to work for some time now. A little about me, I used to be a mechanic and have ridden motorcycles for over 30 years now. I have more recently played around with RC aeroplanes, flight controllers and raspberry pis. I have been recently inspired by Sketch Coleman's 50kw supermoto. I wouldn't need something quite as powerful as that but I would want something that will accelerate similar to an ICE motorcycle. With the drivers around here, I will get run over otherwise. If you're not familiar with Sketch's bike, here's a link to part 4 of his build videos. He clearly has gone "no expense spared" in his build, my budget would not be the same.

    My budget is not fixed but would have to be around the AUD$5k - ish mark for me to consider it worthwhile. There's a fella over on the DIY Electric Car forum who is attempting to build a BMW E36 for under 1000 Euros, so I was hoping to do something similar.

    My commute to work is only 19km (12mi) each way and takes around 25 mins. It is a mix of 60 - 80km/h (40-50mph) with a short (2 min) burst at 100km/h (60mph)if the traffic is good. Sometimes that is a traffic jam and I have to filter through that section. So I don't need a huge range, less if I charge at work but I would probably prefer to just charge at home each night.

    The bike - I was thinking of a Honda CRF250 or 450 or similar, something road registerable. I can pick up one in reasonable condition with a blown motor for around the $1000-$1500 mark.
    The motor - I don't really know what size I would need for decent acceleration but I have been looking at the 72v Golden Motor 10KW BLDC Motor. I'd like to use the watercooled ME1616. but I would need a bigger battery.
    Controller - Sevcon or the big Mobipus or similar, I'm not really sure at this stage.

    With exchange rates and shipping, I would already be up somewhere around the AUD$3.5 - 4k area by now.

    The battery size I would need is something I am having trouble finding information on working out. Secondhand Tesla/Leaf/zero batteries and parts are just not available in Australia and, even if I could find them, they'd be ridiculously priced. I am thinking of using 18650s recovered from old laptop batteries. Haven't found a source for them yet or approximate cost and not sure if this is even realistic and trying to work out how to configure them is confusing. The Zero seems to have a 7.2kWh pack on the standard model and gives a range of around 97km with a city/highway mix. Assuming I get just over half the same efficiency, I'm thinking that this is about the size I need to aim for.

    Check my maths! For a 72v 7.2kWh battery using 18650s with an assumed capacity of 2000mAh and discharge of 1C. (3.7v x 2A = 7.2Wh, 7.2kWh/7.2Wh = 1000 cells and 100A) So I would need 20S50P configuration. Is my maths correct?
    @ 42g/18650 cell = 42kg (93lbs) without nickle strips, solder, wires, BMS, case etc. Sounds a reasonable weight to me. I guess-timate I could fit 7 of the 20s modules where the two radiators would originally be mounted and the remaining 36 inside the frame. Is 100A enough though? I guess peak might be higher depending on the batteries.

    I have read that others who make powerwalls pay around $1/recovered cell so that'll bring me up around the $5k mark. There's then other incidentals like contactors, fuses, throttle, wiring, etc, so that's probably another $1k or so.
    Other things I need to suss out are; getting an engineers certificate so that it can be road registered in my state (Victoria, Australia), and whether an insurance company will actually insure it.

    So how am I doing so far? On track or way off? Any info would be greatly appreciated.

    Thanks,
    Ant
    Last edited by Ant; 5 Days Ago at 1939.

  2. #2
    Empulse R #24 frodus's Avatar
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    I don't think you need water cooling really. The ME1507 is a good sealed, reasonably priced motor. Goes good with a Sevcon.

    For battery, I don't know that you'd need more than 2-3kWh if you're going 12 miles. On my old Brammo Empulse, I would get around 125Wh/mi typically highway. So that'd be about 8mi/kwh. So 3-4 kWh min, and I'd say 4-5kWh would be a good design with overhead. I'd aim for 72-100V (24s is a nice number for BMS, and there's Zeva in AUS that sells a nice 12s BMS board. You could use 2 12s boards, and 1 master and they've got a nice LCD.

    I think with leaf cells or volt cells, you could get the package under $5k with most of what you'd need.

    DISCLAIMER: I'm an EV parts integrator/reseller. I could help you out (www.emf-power.com) with some of what you need.

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  4. #3
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    Hey. Thank you for the info. A 2-4kWh battery would definitely make things a lot easier! I have not stumbled across Zeva's site, I will definitely check them out!

  5. #4
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    Hi
    do not know where you located, but if i would try to build more or less for commuting only i would look for

    a) a typical and popular commuter/bread and butter bike - say cb250, anything that is not too modern and not too fancy. because they usually go for cheap anyway and parts are sold easy.
    most typical commuters are build easy to access good for conversions as we won`t have the skills to pack things as tightly as the originals..
    Off road type bikes seem to have little space for batts.

    b) the cheapest donor i could find ( and it would need to be suiting - space wise) but no leaks ... forks ok...not bent...
    with some luck i got mine for 400 and sold engine/carb for 300 alone - basically for free.

    a bike build for 24 miles commute would not need a big battery, but as frodus said bit more does no harm. Less voltage sag-more fun. Eventhough the samller batts pay off quicker- having some extra for some detours makes it more practical.

    Have a look at used nissan leaf packs.

    Good luck

    flo

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  7. #5
    I should be working! furyphoto's Avatar
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    You definitely won't need 7.2kwh for a 24 mile commute.
    Your speed requirements for your commute are very reasonable, 3-4kw should get you there no problem. You could probable manage that distance on lead to get you going, if lithium is difficult to find. You could probably achieve your required range at 48v.

    Take a look at http://www.evalbum.com/type/MTCY to check out completed builds, many people have posted speed and range performance, as well as the components they used to build their bikes.

    If you can't find leaf or volt cells, you could probably get a hold of some calb, or gbs lithium down unda. 24 x 40ah would probably cover your range. (3Kwh)

    Probably would be a bit cheaper to go brushed DC, vs A.C. or Brushless. Lots of builds done with me1003 motor, and alltrax controller.

    You have lots of options because your performance targets are very reasonable.
    Last edited by furyphoto; 4 Days Ago at 1046.
    -Andrew

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  9. #6
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    Thanks guys.

    @flo

    I'm in Melbourne Australia. A small road bike frame is also an option, I haven't decided yet and it will really depends on what is available at the time I decide to get this project underway. EVs are still rare as hens teeth down here. Zero have tried twice to set up in AU (and pulled the plug twice, last was in 2017). I don't think we have the population (and perhaps longer commutes??) to make it economically viable to sell here. By the time they import the vehicles, they are more expensive than people are willing to pay for them, hence I don't think leaf batteries are an option really.

    @furyphoto
    Yes it has been very beneficial to get some info re; battery sizes. This is something I have struggled to work out. With a lot of the info on the internet that I have found, they either specify the size of the battery with no range, or range with no specifics about battery size/configuration. I presume that there is a lot of assumed knowledge surrounding building an EV. As an ex-mechanic, I am good with low power 12/24v systems but with higher powered systems I have much to research around motors, controllers, battery configs etc. I have seen the evalbum, so much good info there but so hard to filter it!

    Thanks again for the feedback. This is going to be a long term project I think (we have just decided to buy a house) so I am still in the research phase, but I am tired of waiting for a commercially available EV option in AU (that is also affordable) so I think I will eventually build my own.

    P.S I have only just discovered I can "like" posts but that ability seems to time out after a while. I like everyone's posts so far, sorry for the lack of likes.
    P.S.S I fixed it. User error!
    Last edited by Ant; 4 Days Ago at 1654. Reason: Added P.S

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