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bennelson 03-23-2008 07:34 PM

EV contactor use
 
http://web.mac.com/benhdvideoguy/iWe...s/DSC05957.jpg

Can anyone give me advice in using a contactor on my electric motorcycle?

Currently, I am just using a battery cut-off.

All advice welcome!
I have info in more detail at: HERE

TomEV 03-24-2008 10:26 PM

The good thing about using a contactor is that you can use a regular key (and/or handlebar cut off switch) to open the contactor and turn things 'off'. Many contactors have 12 volt coils, but I believe the one in your picture has a 36v coil. 12v is a bit easier to work with as the regular electric system on your motorcycle is 12v. Unless you have a 36v system, controlling HV power with this particular contactor may be problematic.

MetroMPG 03-24-2008 10:44 PM

Do you really need a contactor on your cycle?

A mechanical on/off battery switch is 100% efficient. A contactor isn't.

The other reason people use contactors in vehicles with PWM controllers is as a safety feature on the "throttle" - eg. you twist the grip and a microswitch signals the contactor to close, you release it, the contactor opens. In the event of a controller failure (they can & do fail fully "ON"), your first instinct will be to release the throttle, which breaks the connection, via the contactor, between the motor & battery pack (assuming it's rated to break the max theoretical current).

bennelson 03-25-2008 12:31 PM

The electric motorcycle is 36 volts, so using a 36V contactor presents no problem.

I was thinking that having a real "key" on the dash to turn everything on and off would be nice.

I have heard that it is possible for a controller to fail in the full on position. Currently, my battery cut-off key is down on the side of the cycle, near my right ankle. While reachable while riding, it is NOT quick and convenient to reach. A key on the handlebars would be.

The battery cut-off is also not rated for real high amperage. I have been told that in theory it could melt in the ON position and then not be usable for an emergency cut-off.

There really isn't any amperage going through the cut off when the cycle isn't going, so turning it ON and OFF shouldn't cause any internal arcing.

I figure this is also a good time to experiment with contactors, so I know what I am doing when I work with contactors on the electric Geo Metro conversion.

bennelson 03-25-2008 10:41 PM

I put the contactor on the cycle today.

I installed the forklift "ignition" key where the cycle originally would have had its key.

This connects the 36V battery pack to the contactor coils, which then snaps shut the the contactor, powering up the system.

Definately sexier having an electro-mechanical device on the cycle instead of just a big dumb switch.

Officially, Alltrax's documentation says you are supposed to have both a diode and a resistor in the mix too. Apparently when the magnetic field on a contactor collapses, it can send high voltage backwards, which can cause problems with the controller. The diode stops that from happening. The resistor is supposed to help prevent arcing at the contactor. I didn't see any arcing, so I don't think that's as big a deal.

Besides, I still have 3 more forklift contactors kicking around anyhow!

I picked up up a diode at Radio Shack, and will throw that on tomorow.

Perhaps I will make a YouTube video showing the contactor in action?

MetroMPG 03-26-2008 08:09 AM

Does your system also have a pre-charge resistor to protect the longevity of the controller's capacitors? That was something I didn't know about, but the EVDL Yodas recommend it (so did the Curtis wiring diagram), even though it will work without it.

TomEV 03-26-2008 08:44 AM

I use a resistor across the contactor HV points, and a diode for the control coil. Not sure of the real benefit, but I installed them per the manual. The resistor they call for is fairly high wattage, and is one of the rectangular 1 1/2" ceramic types. Diodes are easier to come by.

bennelson 03-26-2008 11:32 AM

I put on the diode and resistor.

They had the diode at Radio shack, but the closest they had for the resistor was only half the value I needed. Fortunately it was a two-pack, so I just wired the two in series.

The diode is a 3 amp, which is what the diagram called for, but I wasn't sure what voltage was required. I got one marked 200V because the Alltrax literature said that the wacky "EMF counter voltage" can get higher than 150 volts.

Testing shows that the contactor seems to work ok. I haven't gotten any sparks or shorts.

I am going to run the route today that the ZENN NEV will take next month to get from the hotel to the Earth Day EVent. I need to note what the speed limits are through there.

If you don't hear from me again, I am stuck on the side of the road with a blown contactor or controller!!!

bennelson 03-26-2008 06:04 PM

Ran down to the church where the Earth Day event will be. No problems going there and back.

Got both a diode and resistor on the contactor, and NOW A VIDEO!!!

[YOUTUBE]http://www.youtube.com/v/G0sUrXSU9Ok[/YOUTUBE]

TomEV 03-26-2008 06:58 PM

Your motorcycle is a lot quieter than my Citicar! :thumbup:


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