20 January 2014

EtekChopper: Tearing 'er Down and Cleaning 'er Up. Also Battery Mounting & Paint Thoughts...

I've left EtekChopper outside in the rain and cold for the past few months while I was busy doing Senior things like classes and thesis and grad school apps and stuff. Poor EtekChopper! It was under a tarp, but still! Now that some of my own hardware has started to rust, and now that I know it can move around on its own power, it's time to strip it down and clean it up for a final rebuild. No rust, no janky mounts, no zipties, nice insulated electronics, etc. 

Let's begin!

I'm very pleased to say I've joined the MIT Electric Vehicle Team (EVT) and they have graciously allowed me to work on the motorcycle into their laboratory space!!! Now I can disassemble the bike without the risk of people from outside stealing parts. Plus, there's a bit more room to leave parts in a corner than there is at MITERS (which is conveniently located downstairs). 

Things I want to do over the next few weeks:  

  • Strip all parts off
  • Remove ALL rust from the frame parts
  • Design and weld steel tabs to the frame for mounting and protecting
    • Motor
    • Batteries
    • Controller
    • Charger
    • Other components
  • Re-paint or powdercoat (YAY!) frame parts. 
  • Reassemble bike
  • Fix front brake
  • Lower the bike to fit my short body. I'm only 5'8" and this is a pretty large bike. 
    • Raise front fork as much as possible (lowers front of frame)
    • Adjust or replace rear suspension (lowers back of frame)
  • Clean the rest up. 
First things first. I've started to remove everything off the motorcycle, and first comes the seat, gas tank, rear fender and light assembly, front light assembly. 
Then came out all the peripheral electronic components, Cycle Analyst, Throttle, Sevcon controller, wiring...

Then came the chain and rear wheel. And the batteries. And the motor.
The frame is SO LIGHT NOW! I can move it around without much effort. The wheel assemblies on this thing really add on the weight. 

I removed the rear shocks, footpegs, and swingarm. I'm going to have to probably get shorter shocks or make/buy my own lowering blocks. With the CNC mill working, I may just let it make the lowering blocks for me!

I decided I would inspect the front brake (currently non-functional). I opened up the oil reservoir to find a lot of gunk. Following this guide (http://www.youtube.com/watch?v=0X6BX05JAo0) I cleaned it out. I decided to leave it empty (and drain the line and caliper as well) until I re-assembled the whole thing. 

Here I realized that the clamps for the front levers were where the mirrors mounted to! this rusted and sheared piece of bolt was the old mirror! I went to town trying to remove it. I Dremel-ed a slot on the top and tried to use a flathead screwdriver to remove it. I ended up breaking the screwdriver! Even after torching the area (The aluminum clamp would expand more than the steel bolt) and wailing on it with WD40, the thing would not come out. 

I ended up drilling a hole into the bolt and using a screw extractor, which got a little out of hand when the thing wouldn't budge, until it finally...
CRACKed, taking a piece of the clamp before it would move. I used a Dremel to remove as much bolt material as I could (I feel like a surgeon now). I then squeezed the sides of the bolt together and pulled it out. The threads seemed mostly intact, though...

And sure enough, I could get the mirror onto there! I can see behind me! Turns out there are two axes of rotational adjustment: The angle of the brake lever clamp on the handlebar (adjusts it vertically) and the angle of the mirror on the clamp itself (adjusts it horizontally).

Now if I can only find where I put the clutch clamp, which can hold my left-hand mirror... :x
 Now it's time to take apart the front fork. First comes the wheel...

Then the forks and handlebar. Easy enough.

At this point, I need to finalize where I need to weld tabs that will hold my batteries, controller, fairings, DCDC converter, and provide additional bracing for the motor. 

The motor mounting tabs were easy enough to design/make. I just cut some steel L-channel to size, and used a grinding wheel to shape the channels to fit the frame tubes and other bits. These will come out really nice with a MIG welder. 

Now, the batteries. I've decided to NOT use these two 12S8P packs, even though they have a nice BMS and pakage. The truth is, these batteries are unsafe in this cramped mounting position. If I move it far back enough to clear the front wheel and fender while the fork suspension is fully compressed, I cannot mount the plastic rear fender (which protects the components in front of the rear wheel). If I move the batteries far enough forward to mount that protective plastic fender (I have to squish the plastic battery case a bit against the steel frame), the batteries come dangerously close to the front wheel and fender. With a max front shock compression of ~5.5", there's no way the battery can clear the front suspension. Something has to change. 

Enter the smaller 12S4P pack that is available to me via an extremely generous donation. 4 of these packs is equivalent to the two 12S8P long packs I've been testing with, but they are each in a package that is half the size as well. This leads to more (and better!) options for storing the batteries on the motorcycle frame. 

After playing around with them, I found I was able to fit eight (8!!! Double the original capacity!) of the 12S4P battery packs in the front of the motorcycle in a clean and consistent space. Look at how elegant that is! 
I will only be using 6 packs though, for a total of 24S12P. (150% original capacity, 288 cells, 720 Ah, ~ 45 miles of range!)

To fasten these packs I need to design steel mounting brackets to be welded onto the frame. I'm going to add about 0.5" of padding/buffer/armor to each side of the battery to provide some cushioning and protection from rocks/shrapnel that may penetrate the battery pack and short something. I can't design the specifics of this until I have the 6 battery packs, so I will simply design it for a box of 3x2 of the 12S4P packs, with an additional 0.5" on each size. 

I plan to cut cardboard into a box of this size, then design mounting channels in the frame using steel L-channel to allow that box to easily slide into the channel from one side, then clamp down using webbing or some other type of clamping method. 

An interlude: I have to thinking about the painting process. The problem with the process is many things have to happen quickly after eachother, or the frame will oxidize or the primer/paint will not hold corrctly. I'm going to follow these basic steps:  

  • Sandblast frame to remove rust+old paint (start the oxidation clock)
  • MIG Weld tabs to frame in proper areas
  • Move frame to a dry, warm, and ventilated location and suspend frame 
  • Clean entire frame with acetone or denatured alcohol or mineral spirits. 
  • Coat frame with primer (RustOleum automotive primer for metal)
  • Wait the specified primer recoat time (about an hour acc to the label)
  • Spray LIGHT coat of color paint (RustOleum Semi-gloss black enamel). Wait recoat time. 
  • Spray main coat of color paint. Wait recoat time. 
  • Spray final coat of color paint. Wait recoat time. 
  • FINELY sand/polish the frame to make shiny. 
  • Coat with a clear gloss paint (RustOleum Clear Gloss Enamel). 
  • Final surface polishing. 
  • Leave in warm, lit area for some time (on the label). Maybe use a hot lamp?

All that must happen with very minimal interruption, especially the painting portion. Oh boy, what did I just get myself into... But first I need to finalize my battery mounting.

See you next post!


  1. Hi !

    I was looking through your photos of the build.
    I think you have the positive battery connection connected to the wrong terminal.
    From the manual it seems you have bypassed that 355A fuse and connected your contactor directly to the positive input of the controller. Page 32 of the Manual you have linked to shows the connections.

    I really appriciate your blog and all the descriptions and how to's.
    I'm about to install a Sevcon in a bus for a museum and found your page very interesting and informative.

    I hope to get all the software and wiring correct in one day.
    But I have not gotten the controller and connectors yet.
    We're replacing a Kelly controller.

    Best Regards
    /Per Eklund

  2. A lot of cool information is on this blog.