Electric trail bike

Discussion in 'Some Assembly Required' started by Luke, Jul 27, 2011.

  1. Luke

    Luke GPoET&P

    Joined:
    Aug 25, 2004
    Oddometer:
    4,249
    Location:
    Beaverton, OR
    [​IMG]

    I'm just getting started, but here's what I have. An electric trail bike based on a '99 YZ125. Everything is assembled, wired, and running. It needs a lot more work to get it into a useful state. I don't have much to show right now, but I'll get some pictures of the components and go into what it took to get to where it is now.

    Until I figure out embedding vimeo videos; http://www.vimeo.com/26986399
    #1
  2. alphaBETAdog

    alphaBETAdog Been here awhile

    Joined:
    Feb 25, 2011
    Oddometer:
    305
    Location:
    Central Arizona
    Excellent Luke! :clap Keep pluggin away (pun intended)!
    #2
  3. DaveRMS

    DaveRMS Long timer

    Joined:
    Jul 20, 2005
    Oddometer:
    1,218
    Location:
    San Rafael, CA
    Awesome Luke!!!
    #3
  4. oregoncoast

    oregoncoast Racing Like a Noob

    Joined:
    May 15, 2007
    Oddometer:
    4,543
    Location:
    Duh!
    Luke is da man. Where's that link to the video of it running though??? :1drink
    #4
  5. Luke

    Luke GPoET&P

    Joined:
    Aug 25, 2004
    Oddometer:
    4,249
    Location:
    Beaverton, OR
    Right at the bottom of the post.

    It embeds perfectly in the 'test your embed video' thread, but not here. Go figure.

    Here, I'll try again:

    <iframe src="http://player.vimeo.com/video/26986399?title=0&byline=0&portrait=0" frameborder="0" height="300" width="400"></iframe>


    Edit again: One message to the mods and it works! Embedding wasn't turned on for this forum yet. Thanks Johnjen!
    #5
  6. oregoncoast

    oregoncoast Racing Like a Noob

    Joined:
    May 15, 2007
    Oddometer:
    4,543
    Location:
    Duh!
    Yep. I could not get it to work here either...lol. :lol3
    #6
  7. Zachsv

    Zachsv SVhaver

    Joined:
    Sep 10, 2010
    Oddometer:
    162
    Location:
    Wilmington, NC
    I hope you get it worked out right! I would love to have an electric dirtbike capable of a couple hours of medium riding. Would be amazing to tear through some woods w/o bothering the houses that are near.
    #7
  8. OaklandStrom

    OaklandStrom Long timer

    Joined:
    Sep 17, 2005
    Oddometer:
    1,612
    Location:
    East Bay
    Cool project!


    Just out of curiosity, exactly which city in Oregon is idiotville? I think there's more than one possibility. My vote is for Springfield.
    #8
  9. Luke

    Luke GPoET&P

    Joined:
    Aug 25, 2004
    Oddometer:
    4,249
    Location:
    Beaverton, OR
    So I have a few goals for this bike. They may be modest, but they're goals.

    1: Built like a real woods bike. I'm basing this on a full sized bike's chassis, and it needs to not weigh much more than the original bike. The YZ has a claimed weight of around 210 pounds, I didn't check the actual weight before stripping it and I'd like it to end up the same after conversion, but I figure if I keep the weight under 250# that'll be good enough. That's the weight of a modern 250 4 stroke. I'd prefer lighter (sub 225#) but we'll see what I get.

    2: Good performance. It needs nice smooth power delivery, especially since there is no clutch to mask any thottle issues. It also needs to wheeley. Top speed should be good enough for local trails, which is around 25 mph.

    3: 10 miles of range. That's not much, but if it can be recharged quickly and/or have swappable battery packs then that's good enough for around here. My trials bike has about a 20 mile range and that's enough for a good multi-hour trail ride.
    #9
  10. Luke

    Luke GPoET&P

    Joined:
    Aug 25, 2004
    Oddometer:
    4,249
    Location:
    Beaverton, OR
    Thanks!


    No, it's not Springfield. With all respect due our beloved Springfield ADVer's, that's a pretty good guess though.

    I actually live in Beaverton; Idiotville is an old logging camp in the coast range where I usually go trail riding. http://en.wikipedia.org/wiki/Idiotville,_Oregon. Surprise, it's a real place. :lol3
    #10
  11. Luke

    Luke GPoET&P

    Joined:
    Aug 25, 2004
    Oddometer:
    4,249
    Location:
    Beaverton, OR
    Anyway, since I have some pictures of them, let's start with the batteries.

    There are a zillion different kinds available. It turns out, though, that only one type will deliver the sort of power* that I want. They are a lithium cell made by A123. They're the same one used in the electric drag race bikes, and in the lightweight replacement starter batteries. The bad news is that they are only made in a long-C cell size, not a big rectangular pack. So I would have to build a big pack out of a lot of little cells.

    *Batteries are usually rated by how much energy they hold, which translates into the range of the bike. Almost as important is the amount of power they can deliver, which translates into the power of the bike.

    The cells are expensive, and would be hard to pack into the available space. A little math showed that 100 cells would make a pack that would deliver most of the power that the motor could use. So I paypalled $800 to some guy on ebay and crossed my fingers.

    He delivered.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    And one pack is filled. It isn't wired yet. The two packs are different sizes due to the way everything mounts on the bike. This one is smaller, a grid of 9 cells in series, 5 parallel. The other is 11 series, 5 parallel.

    Lithium cells require management, and I couldn't find anything off-the-shelf that I liked, so I built these:

    [​IMG]

    They limit the voltage to each cell to prevent overcharging, tell the charger when each cell is nearly charged to get the charger to slow down, and tell the bike if the cell voltage gets to low so it doesn't discharge them too much.
    #11
  12. earwig

    earwig Crowbar of Embrayage

    Joined:
    Apr 25, 2006
    Oddometer:
    4,726
    Sweeeet!!!! :clap


    What an amazing project, and the bike rides really nice already. I can't wait to see how it feels after some of your power delivery tweaks!

    Luke, you are an inspiration. Majorly impressive accomplishment!
    #12
  13. Grider Pirate

    Grider Pirate Long timer

    Joined:
    Sep 28, 2007
    Oddometer:
    1,686
    Location:
    LV, NV
    What motor are you using? Brushless?
    Nice project!
    #13
  14. DireWolf

    DireWolf Knees in the Breeze

    Joined:
    Jun 6, 2006
    Oddometer:
    13,437
    Location:
    In the Mustard Booyah. Whooop!!
    :bow
    #14
  15. a1fa

    a1fa Throttle Jockey™

    Joined:
    Nov 1, 2006
    Oddometer:
    13,907
    Location:
    Arkansas
    :lurk
    #15
  16. Luke

    Luke GPoET&P

    Joined:
    Aug 25, 2004
    Oddometer:
    4,249
    Location:
    Beaverton, OR
    It's an Agni brushed DC motor. Among the motors I could find that had the right amount of power it was the lightest. As a bonus, it's a lot easier to control than the brushless types, which makes things much simpler.

    The Agni is rated for around 38 ft-lbs of torque for 5 seconds, which is similar to a 600cc 4 stroke. The continuous rating is half that, which will hopefully be fine in real use. The bigger problem is that there's no transmission, so I have to pick one gear ratio and stick with it.
    #16
  17. Luke

    Luke GPoET&P

    Joined:
    Aug 25, 2004
    Oddometer:
    4,249
    Location:
    Beaverton, OR


    I need to mention that Earwig has graciously allowed me to work in his shop, which in addition to having much more space than my garage, has much more understanding neighbors.

    Thank You.
    #17
  18. Paul_B

    Paul_B Been here awhile

    Joined:
    Mar 23, 2007
    Oddometer:
    364
    Location:
    North Central Ct, USA
    Awesome project!

    What motor controller will you be using? I (and lots of others here I'm sure) would love more technical details and pictures.

    This really is a cool project, best of luck.
    #18
  19. PhotoBiker

    PhotoBiker Please insert title here

    Joined:
    Sep 26, 2008
    Oddometer:
    1,442
    Location:
    Southern Maine
    Cool thread.

    I've only mucked with electric on a much smaller scale for RC Helicopters years ago (before Lith) but am able to follow you.

    I thought building up an 18v pack of Nicads was a PIA ;-)
    #19
  20. Mr. Fisherman

    Mr. Fisherman PROUD 2B Riff Raff!

    Joined:
    Oct 8, 2006
    Oddometer:
    10,939
    Location:
    Drinking from the Stanley Cup!
    I have been waiting for this one...
    Great stuff.... :clap:1drink
    #20