Maiden Voyage @ 72V

So, last night I went to Synkromotive and talked to David and Ives about some GUI ideas, and then Ives, Loni, David and I started wiring up the motorcycle and mounting the controller/contactor/fuses. Ives was dead set on getting that bike running that night. I’m glad he helped out and got the code modified for my controller (a little different).

The battery wiring was mostly done last week, but I took the + and – of each 72V pack and brought them out to the controller and contactor. Fused for 300A for now. We wired the controller to the contactor (it controls the main contactor), the throttle, the keyswitch, precharge resistor and we installed an “emergency contactor dropout” button (we used the horn for now). David mounted the controller to the motor mount (temporary), Loni fabricated a mount for the contactor and a motor support tab (to be installed later). I worked on getting the power side wired and fused. Loni’s friend was there and helped get some cables crimped. We all worked together on getting this thing together. Jim was busy in the office working on the website. Its so funny that all 5 of us (discluding Loni’s friend) have our little niche in Synkromotive, and we all pulled together to get it going. Thanks guys!

When we turned it on, and got the controller connected to the laptop, we noticed that the controller was getting precharge (internal precharge resistor), but it wasn’t getting full power. The Contactor seemed to have a 12V drop across 1 set of contacts, so we used the other pole (2 pole, single throw). We connected it, and the controller was now powered up. With some setpoints in the controller, Ives eased on the throttle, and voila, fully controlled smooth acceleration of the rear wheel. He spent another few minutes setting some current limits and battery cuttoff/pullback limits. Its got limits in it so you can have the controller pull back when voltage sag reaches a certain point. Very useful for extending battery life.

We filled the tires with air (they’ve been sitting a while), tightened all the bolts, wire tied everything down, and prepared her for the first ever run under electrical power.

I decided (because I hadn’t really riden a sportbike before, and didn’t know what to expect) to let David and Jim ride it first. David took it outside, and took it around the block. He went around a couple times, and came back… the acceleration was a little lower than we would have wanted. The gear ratio is 3.38:1. Jim got on and rode it around a couple times. Ives tweaked it a little each time to try and get the acceleration a little better.

Then it was my turn. I didn’t know what to expect, but put on the helmet and gloves, and prepared for my first onroad motorcycle ride. With a twist of the Magura throttle, I was off. Nothing but the sound of air rushing past my face (and a slight chain noise). We had to keep it in the area around Synkromotive where it was lit, but there was plenty of light to see. No traffic this late at night, so its a great test area. I rode around a couple times, and decided since it was late, we ought to go in. I had the biggest EV Grin on my face afterwords. I don’t care if the sprocket ratio is wrong, I’ve got a f*ckin electric motorcycle now!

I wanted to start with the stock rear sprocket (replacing is almost $100, and if I didn’t need to replace it, I was going to stay stock). I got a 13, 12 and 11 tooth front sprocket to play around with ratios between 3.38:1 and 4:1. We’ll change the sprocket tonight for 11tooth and see if it helps a little. Next step is to get a ratio closer to 5:1 (56 tooth?). It might normally hurt top end speed, but 72V is only the first step. The final design will be 144V, and we won’t be limited to the RPM at 72V. We can go to the upper limits of the motor. We just need more low-end. 56tooth and a 13tooth would give 4.3:1, 12tooth would be 4.66:1 and 11 would give 5.09:1. might go to a 60 tooth, but we’ll see. I’d like to be able to change it around easily with the chain I’ve got until I find a good ratio. having 3 different front sprockets makes it easier.

So yeah, It was a blast. Here are some pictures (click on the pic) of wiring/riding.

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3 Comments

• By Taylor Wilson, June 18, 2008 @ 10:21 pm

  Project looks awesome! I go to OU and am in the middle of converting a 600cc Ninja. Had a few questions for you. Give me a shout! Tried to find an email on the site and didn’t stumble across one.

• By Jake, June 19, 2008 @ 1:26 pm

  Sweet….I guess range tests are next!

  I’m still working out some battery pack issues on the Rezistor, but should have it running again in the next couple weeks.

  Congratulations!

• By Andy, June 19, 2008 @ 3:27 pm

  Fantastic! I am looking forward to seeing some video on youtube of your bike! It is sweeet!

  Andy,

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