I recently got to take apart a Mars motor. It's really nice inside. The brush design is FAR better than the original Etek. (It uses the more traditional way of holding brushes, but it's a very large diameter commutator. Nice springs too.)
So, for any of you who thought my last video posting showed how my motorcycle was complete..... you couldn't be further from the truth!
What I did was get the cycle "Show Ready" for the MREA and another event.
When an electric motorcycle is parked as part of a car show, it DOESN'T need headlights, turn signals, horn, tail-light - in fact, ANY part of the original wiring harness. (It did need a working drive system for me to drive it up into the back of my pickup truck....)
When I got my cycle frame, it was in pretty poor shape. When I converted it to electric, I completely replaced the original wire harness. Parts of the original harness were actually MELTED OFF! When I built the harness for the original version of the e-cycle, I didn't do a great job - it was a real mis-match of wires, and none of them were really the right length.
So, the other day, it was time to rebuild the harness, and do it right this time! Fortunately, my brother, Wayne, was around to give me a hand. He's much better at this whole "plan ahead, and be organized" thing... He even already made a wiring diagram!
Here's him popping in the headlamp, with the new color-coded and labeled wires inside.
And here's him working on the harness in general. I assure you the wires were much more tidy than that by the time we got done!
The main thing that kept me busy, while he was working on the wires, was the Dc/DC converter.
You see, my motorcycle does NOT have a 12V battery dedicated for the headlight and other traditional 12V items on the motorcycle. It just has the 4 12V batteries in series for the propulsion system.
So how does one get a separate 12V for just all the accessories? Just connect that all up to one of the four batteries? No, that's not ideal. That one battery gets loaded down a little more than the other three, but worse yet, it makes an accidental ground between 48V and the frame of the bike that much more likely!
So, I'm using a DC/DC converter to take the 48V and convert it to 12V (OK, 12.5 if you want to get technical....) to run the accessories.
This way, it's an even drain on all batteries and isolates the 48 and 12V systems.
Here's what I used.
It's a two-inch-square converter out of some computer equipment. It will convert anywhere from 36-72V out to 12. That's nice to have that type of range. If my batteries are low on juice, AND I gun it GOING UPHILL, at NIGHT, the low-voltage cut-off is STILL below what the batteries will provide.
(A few summers ago, when I was running the cycle on a 36V system, I WAS going up a big hill, at night, at the end of my ride.... The headlights kicked out! Yipes!)
The only real downside of this converter is that it has small pins for the power. Those were designed to go into circuit boards, not motorcycles! So, I crimped on some bare space terminals and then soldered them to the pins. Now I have quick-release connectors and can just plug and unplug the converter from the cycle.
The DC/DC converter is rated at 100 watts and 86% efficiency. The headlamp uses 55 watts, and the tail and turn signals don't draw much. (The tail light is LED)
Based on the efficiency, I would imagine that the device gives off the same amount of heat as a 14 watt lightbulb. It's mounted to the same alumimum plate as the controller and everything else. I think that should work as a bi, simple heat sink.
I also really like the Sharpie silver marker. It writes on black!
So, now when I turn the key on the cycle, it turns on power to the controller, and power to the DC/DC converter, which outputs 12V to activate the main contactor, which fires up the 48V to the motor.
One key does it all!
So, now the cycle is not just show-ready, but ridable as well! That means it's time to start teaching others how they can build their own.
I just started work on my BUILD YOUR OWN ELECTRIC MOTORCYCLE instructional DVD. If you have any particulars that you want covered in the video, let me know!
