EtekChopper: Electrical Mega-Update

Brace yourselves, this is a Mega-Update!

Last we left off, the mighty brushless Etek/MarsElectric/Motenergy motor had its sensors replaced. It's now time to start putting everything together to start rotating these tires.  

The 35-pin AMPSeal connector required by the Sevcon Gen4 came in, as well as the proper crimp terminals. It's a beefy connector, with rubber gaskets and other protection to ensure the leads do not short and that rain stays at bay.

Looking at the Sevcon wiring diagram in the manual, it dawned on me how complicated this setup was going to be. I need a Main Throttle, a Regenerative Braking Throttle, a Key Switch for logic power, a Contactor to enable supplying motor power, Hall Sensor inputs, an Enable Switch, and CAN Bus inputs for programming the controller with the motor settings and desired configuration. Ultimately, I identified the exact pins I would require: 

• 1: Key Switch In (Supplies logic power. There are three of these for convenience.)
• 2: CAN Termination - Short to pin 24 (CAN Bus)
• 3: Contactor 1 Return
• 4: Contactor 1 Supply
• 5: Encoder "U"
• 6: Key Switch In
• 10: Key Switch In 
• 13: CAN High
• 15: Encoder Return 
• 17: Encoder "V"
• 18: Forward "Enable" Switch
• 22: Main Throttle Wiper In
• 23: Braking Throttle Wiper In
• 24: CAN Low
• 26: Encoder V+
• 29: Encoder "W"
• 34: Main Throttle Supply
• 35: Braking Throttle Supply

I started wiring some of this for an eventual initial test, but first I wanted to check whether the key switch on the motorcycle was sufficient for switching 72V at low current. 

The Key switch in the OFF position does not switch anything, nor does the Lock position, which locks the handlebars of the motorcycle to prevent theft. ON short two of the leads emerging from the switch, and P (Presumably "Park") shorts two others. It seems beefy enough to switch 72V at a low current. Looking further at the bike, I took to figuring out what parts of it to keep or throw away when it came to wiring and indication. 

The original HUD for the bike has a speedometer, engine tachometer, left and right turn signal indicator lights, odometer, brake light, oil pressure light, and high beam indicator light. While somewhat useful, I plan on using the Cycle Analyst (More on that later) as my speedometer and odometer, I can see whether or not the turn signals, brake, or high beam, are activated, and an engine tachometer is not useful if I'm not going to be shifting gears. 

This handlebar-mounted switchbox seems really useful, however. It sports a high-beam light switch (Low beams are always on on a motorcycle by default), Left and Right turn signal switches... 

And a horn button, all in one nifty package. I'm keeping this!

I also received the Cycle Analyst High-Current edition and 0.5-Ohm shunt in the mail. It has a lot of great features, and will serve as my battery voltage indicator, current/power draw indicator, "Gas" (capacity remaining) indicator, Speedometer, and both trip and Universal Odometer. The Cycle Analyst even has more advanced features  to limit current draw or maximum velocity (by putting it between your throttle and motor controller). Because I'm using such a smart motor controller that can already do this, I am foregoing these features. 

The screen is HUGE, and the buttons feel great. It's backlit, waterproof, and runs off of battery voltage. 

It comes with a magnet,which attaches to the bike wheel, and hall sensor which attaches to the front wheel fork. This, coupled with a programmable wheel size, allows the Cycle Analyst to accurately measure velocity and integrate it to act as an odometer. 

The High-Current edition of the Cycle Analyst requires the purchase of a separate shunt resistor for current sensing. This is a 0.5 Ohm shunt, and it's beefy, and can apparently handle 150A continuous (400A peak). 

  The instruction manual is well put-together, featuring informative diagrams and instructions. There's even information on how to hack the device by adding throttle input-output, modifying throttle limit curves, hooking up to a computer for data logging, and even uploading your own firmware. But more on this later, there were more wiring things to test!

Like the lights! While I had the motorcycle inside, I decided to check every light I had. Thanks to one of our favorite awesome battery company's bricks, I verified that the signal lights work, but weren't blinking (yet).

Here's the rear light that's always on. 

And here's the rear light + the brake light in tandem. Sweet. 

Now, because the previous owner of this bike purchased it to remove the exhaust pipes and take the front headlight and turn signals lights. Because of that, he gave the front windshield/headlight/turn signals from another motorcycle. I didn't plan on putting the entire assembly on my bike (It was kinda broken, and I'm not sure it could even mount onto my bike) so I decided to take them all apart and test them. I'll mount them individually with my own adapter hardware if necessary.

It's a shame, it's a really nice front windshield assembly. But hey, onwards. 

I found the part of the motorcycle that makes the turn signals blink! It's a relay-looking thing that probably operates on the same principle as thermally PWM-ing electrical stovetops. Wicked.

I decided to try and start fitting components to the bike while I had it indoors. They... kinda... fit? I'm gonna have to massage the bike a bit to fit those batteries. Chances of me fitting twice the amount of batteries are pretty slim...

 WIRES! I found some of LOLriokart's leftover heavy duty wiring somewhere in MITERS. I need to ensure all my wiring can handle the 350 Amps peak without melting, so 2AWG it is for me! In a hardheaded attempt to get the motor spinning RIGHT NOW, I bought the local True Value Hardware out of all their 2AWG ring terminals. All 6 or so of them. 

 One soldering iron was not enough to properly solder the terminals onto the wire that was about as thick as my thumb. Two irons were also barely enough. So i settled for a propane torch, which ended up working out quite nicely. 

 I dig the result.

 I then acquired the second of the 12S8P A123 packs, and machined an aluminum bus bar to strap between the "+" of one battery and the "-" of another. This left me with ~72 Scary-Ass Volts of A123 goodness. The whole thing was like 30 lbs. I can't even fathom how heavy that would be in Lead Acid packs...

The Tyco Kilovac EV200 is a 12V-activated contactor which can deal with a metric-ass-ton of current. That circuit you see (it's normally hidden beneath a plastic panel) is an Economizer, which ensures low power consumption after the initial contact and current surge. However, according to this post, the Sevcon has built-in economization, and actually cannot work with the Economizer of the EV200. I removed it and soldered the red and black leads directly to the two black leads. 

And here's everything needed to test the rig, almost ready to rock!

It will rock soon, I swear. 

Just hold tight.