Experimental Electric Vehicles

February 1, 2010

E*Speed update

Filed under: 1 — tonyhelms @ 6:51 pm

Well its been a while since I have updated on the Motorcycle progress. Unfortunately its nothing very exciting, but some progress has defiantly been made.

The process of wiring the entire Motorcycle together starts at the drawing board, literally. The first thing I recommend to anyone who plans on making even a semi-complicated circuit is to draw it out on a piece of paper. You dont have to use official schematic symbols or even use straight lines, just draw it so you understand how the circuit is going to operate. I do recommend using a red colored pencil and a black one for power and grounds, This will become an aid when trying to understand where power is going and when you need to branch off power to another device.

I first decided to mount and wire up the charger port for the bike. This was strategically placed right where your left leg rests against the bike to ensure you will never forget to unplug the charger before you tear out of your garage.

The charger wiring is simple, positive goes to the positive connection AFTER the main fuse but BEFORE the contactor (Main relay). The negative is connected to the negative battery post, or the frame ground.

Wiring the pre-charge circuit is done differently by many people, but I decided to wire it this way because I do not want ANY current running through my bike when it is “off”. The purpose of a pre-charge circuit is to apply a small regulated amount of power to the speed controller bypassing the contacter completely. This circuit it wired with a small momentary push button switch, when depressed is sends positive battery voltage through a 1000 Ohm resistor then to the speed controller. This then slowly charges the capacitors in the speed controller to near full battery voltage within five seconds or so. After holding the button down for approximately 5 seconds the capacitors are charged with battery power, and then the contacter (main relay) can close applying full battery power, then the motorcycle is ready to drive.
If you do not have a pre-charge resistor you risk surging your speed controller capacitors to the point of failure, and at the same time damaging the main relay contacts, or possibly welding them permanently together!

This may sound like a complex activation sequence for the motorcycle, but in a nutshell you hold the pre-charge button for about five seconds, then flip the “on” switch and you’re ready to drive!

Another device to wire to your contacter is the polarity reverse blocking diode, this little diode is responsible for preventing the contacter from surging reverse polarity power through the system when the contactor is shut off. The theory is that when the contacter is shut off the magnet inside the coil of wire springs back and actually produces electricity, but unfortunately it is the reverse polarity! This can be very damaging to other components, therefore this small diode prevents this reverse polarity electricity from damaging anything.

-The direction the diode is installed is very important!

Another safety feature I am implementing is the kick stand safety switch, this will keep the speed controller from activating unless the kick stand is in the up position. If for any reason the kick stand is ever lowered the speed controller will be disabled until it is returned to the up position. This was put into place to prevent accidental throttle activation when the bike is parked, remember you cant hear an electric motorcycle idling, because they don’t!

-The switch is the small black plunger on the right just above the kick stand

The fuse box, DC/DC converter, and Arduino computer have been installed in the rear of the bike. This has allowed me to start the 12 volt vehicle wiring, headlights, turn-signals, horn, brake lights, etc… Most of this wiring has been completed and everything expect the brake lights are currently operational. The Arduino computer and two L293NE control chips are part of a thermal warning system that I am currently wiring and programing with the help of the C++ based Arduino programmable board, There will be a very informative post on this entire system including the programing in the near future as it is completed.

Stay tuned, more to come!

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