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Thread: how does a electric motorcycle come together?

              
   
   
  1. #1
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    how does a electric motorcycle come together?

    I have a very basic understanding of the major components, like the motor, controller, battery, charger. I know you need these things, and that you need a place to mount them. That's pretty much where my knowledge ends. I would like to understand how it all comes together, for a motorcycle that's used for actual utility (eg. 10-12 kWh, 96V) that has a 80+ mile range.

    1. does there need to be a battery management system? and how do you integrate it? I suppose this would be a bigger issue if you decide to use a ton of 18650 cells, instead of bigger battery modules. what about temperature considerations? I imagine if it's 100 deg out, and the bike is doing 70 on the highway, there might need to be an active cooling system for the batteries and/or motor?

    2. how do you hook up the battery to the controller, and motor such that they work the way you want? I guess the controller is kind of the "computer" that's supposed to understand everything. But I've no idea how they work.

    3. how do you integrate the other electrical components, such as, the dash (speed, battery temperature, state of charge), the turn signals and headlights, where are they supposed to go? I'm sure I'm forgetting other things such as relays and switches. (my electrical engineering knowledge is limited)..

    4. what's the approximate cost? i figured in terms of pack energy density, nissan leafs is the simplest option. you'd need 23x 440Wh modules to make a 10 kWh battery, and that comes out to be around $2.5k. i've not done any research on the motor, controller, or any other electrical and mechanical components, some of which might cost an arm/leg because of how rare they are.

    5. what other important considerations am I missing?
    Last edited by Spectastic; 2 Weeks Ago at 1310.

  2. #2
    Member Nicman's Avatar
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    That's a lot of questions! But I'm happy to try and answer a few that I have experience with.


    1. does there need to be a battery management system?

    I personally do not use a BMS, although a lot of people recommend it. BMS will help keep you battery pack at the upper and lower limits, also monitoring and controlling the amount of voltage that each individual cell gets, to keep the module balanced.
    I periodically check my cells, one at a time with a voltmeter, to make sure they are all within .01v of eachother. Since they are all in series, they distribute the voltage equally.
    Temperature control is important, some motors require liquid cooling (ME1616 *drool*) and some modules require liquid cooling (tesla modules).
    Pouches tend to expand, and cylindrical don't tend to expand. I have 11 Nissan Lead 64AH in my bike and I have never had any issues with heat. I live in Florida and we have hot summers!

    2. how do you hook up the battery to the controller?
    There are a few different types of controllers, and it depends on your motor. If you have a motor that uses 3P like the ME1616, you need a sin/cos controller to control each phase. If you have a motor that only needs a (+) and (-) like the ME1002, you only need a controller that limits the voltage, like the Alltrax SR-72400.
    There are some really good resources on this forum that have in depth discussions regarding controller and motor selection based on goals.

    3. how do you integrate the other electrical components?
    You can make your own wiring harness, or reuse the OEM harness like I did. I recommend making a new harness because you may need to relocate a few controls or dash telemetry. Plus making your own looks neater and gives you a better understanding of how everything fits together so you can diagnose any problems in the future. After that, you can buy a DC-DC converter to step-down your pack voltage to output ~12volts so you can run headlights, turn signals and the horn plus any other 12v accessories you will need. Hooking up the dc-dc converter in place of the original 12v battery is a good location since the positive and negative terminals should be right there for you.

    4. what's the approximate cost?
    Boy, that is a loaded question. If you reuse a ton of products, deal hunt, negotiate, buy in bulk and resell extra, you could probably get away with spending about $3,000 on a full conversion. Remember though, you need all of the non-glorious parts to make it work, power wire, contactors, sprockets, chain or other drive methods, throttle, regen or no regen, diodes, pre-charge resistors...etc.
    Also it depends on if you want to be able to charge fast,(high amperage charger) have extra range, (paralleling batteries).

    It's hard to say really. After all was said and done, I spent about $4,200 converting my first bike, and I think I can get away with about $3,200 with my next bike. I learned a lot, have some of the required tools from the first build, and a few leftover parts. I also have a much better idea of where to buy and what price is competitive to get what I need. I recommend you get in touch with Frodus about parts and any specific questions you have. He has been a monumental help to me and many others on this forum. He also sells a lot of common components at a competitive price.

    As for energy density, that will all depend on the AH and weight of the batteries you choose. 18650s are said to have over 200WH/Kg and as of this moment I don't think anyone else has much over 150WH/Kg. Nissan Leaf cells are awesome, but wait for 2019 when the new cells come out. They will be pricey but are said to have around 60KWH.

    These sites have a lot of good information
    https://electrek.co/
    https://evbatterycenter.com/
    http://www.emf-power.com/

    There are many others but I am at work (on a slow day) so I have only a bit of time to try and help. I am also relatively new to the whole DIY Electric Motorcycle game, but learn more every day and more each time I build a component.
    I'm glad to see you are interested in E-Bikes, and I hope this helps gets you started on your first bike.

  3. Likes Stevo liked this post
  4. #3
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    Quote Originally Posted by Nicman View Post
    That's a lot of questions! But I'm happy to try and answer a few that I have experience with.


    1. does there need to be a battery management system?

    I personally do not use a BMS, although a lot of people recommend it. BMS will help keep you battery pack at the upper and lower limits, also monitoring and controlling the amount of voltage that each individual cell gets, to keep the module balanced.
    I periodically check my cells, one at a time with a voltmeter, to make sure they are all within .01v of eachother. Since they are all in series, they distribute the voltage equally.
    Temperature control is important, some motors require liquid cooling (ME1616 *drool*) and some modules require liquid cooling (tesla modules).
    Pouches tend to expand, and cylindrical don't tend to expand. I have 11 Nissan Lead 64AH in my bike and I have never had any issues with heat. I live in Florida and we have hot summers!

    2. how do you hook up the battery to the controller?
    There are a few different types of controllers, and it depends on your motor. If you have a motor that uses 3P like the ME1616, you need a sin/cos controller to control each phase. If you have a motor that only needs a (+) and (-) like the ME1002, you only need a controller that limits the voltage, like the Alltrax SR-72400.
    There are some really good resources on this forum that have in depth discussions regarding controller and motor selection based on goals.

    3. how do you integrate the other electrical components?
    You can make your own wiring harness, or reuse the OEM harness like I did. I recommend making a new harness because you may need to relocate a few controls or dash telemetry. Plus making your own looks neater and gives you a better understanding of how everything fits together so you can diagnose any problems in the future. After that, you can buy a DC-DC converter to step-down your pack voltage to output ~12volts so you can run headlights, turn signals and the horn plus any other 12v accessories you will need. Hooking up the dc-dc converter in place of the original 12v battery is a good location since the positive and negative terminals should be right there for you.

    4. what's the approximate cost?
    Boy, that is a loaded question. If you reuse a ton of products, deal hunt, negotiate, buy in bulk and resell extra, you could probably get away with spending about $3,000 on a full conversion. Remember though, you need all of the non-glorious parts to make it work, power wire, contactors, sprockets, chain or other drive methods, throttle, regen or no regen, diodes, pre-charge resistors...etc.
    Also it depends on if you want to be able to charge fast,(high amperage charger) have extra range, (paralleling batteries).

    It's hard to say really. After all was said and done, I spent about $4,200 converting my first bike, and I think I can get away with about $3,200 with my next bike. I learned a lot, have some of the required tools from the first build, and a few leftover parts. I also have a much better idea of where to buy and what price is competitive to get what I need. I recommend you get in touch with Frodus about parts and any specific questions you have. He has been a monumental help to me and many others on this forum. He also sells a lot of common components at a competitive price.

    As for energy density, that will all depend on the AH and weight of the batteries you choose. 18650s are said to have over 200WH/Kg and as of this moment I don't think anyone else has much over 150WH/Kg. Nissan Leaf cells are awesome, but wait for 2019 when the new cells come out. They will be pricey but are said to have around 60KWH.

    These sites have a lot of good information
    https://electrek.co/
    https://evbatterycenter.com/
    http://www.emf-power.com/

    There are many others but I am at work (on a slow day) so I have only a bit of time to try and help. I am also relatively new to the whole DIY Electric Motorcycle game, but learn more every day and more each time I build a component.
    I'm glad to see you are interested in E-Bikes, and I hope this helps gets you started on your first bike.
    thanks for the awesome post. the reason i asked was because i have a donor motorcycle that i've thought about converting to electric. But it looks like the process is quite a bit more involved than what I had originally thought. it's something that'll take a lot of time and a lot of money. and honestly, i have other things i want to do. maybe i'll start with a high powered electric bicycle and maybe work my way up from there. thanks again for your insight.

  5. #4
    Senior Member Stevo's Avatar
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    +++ everything Nicman posted! The build process is an educational experience that you wont regret and can't get any other way...and a good education isn't cheap.
    Time is money too!
    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

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