Sevcon

The replacement controller from Team Delta arrived on Wednesday. Fantastic service from Dan, considering I just explained the problem to him on Sunday. I installed it and, at first, got the same "MOSFET short circuit" error message from the controller as before. I wondered if the contactor might be faulty, so I took that out, fiddled with it as much as I could (which wasn't much) then reinstalled it. But then it occured to me that the 12V converter might be faulty, so I left that disconnected. That must have been it, because the scooter worked after that. Changing the controller setup from "speed" control to "torque" control did the trick.

But without the converter, I had no lights or horn. So on Thursday night I pulled out the converter and tested it. It was bad...somehow I had blown it out and it was creating a short-circuit between the negative battery terminal and the B+ connection on the Sevcon controller - hence the MOSFET short error message. So Sevcon has been vindicated; the controller was not bad after all.

Good thing I had the foresight to buy two converters - I installed the second one, this time with a fuse on the + input wire. Lights and horn were restored.

Thursday night I also installed the turn signals I made (LEDs, acrylic, and 5-minute epoxy) and a couple of mirrors. Turn signals aren't working, though...I think the LED's aren't creating enough of a current draw to activate the flasher, or maybe I have something wired wrong.

I made a little "REZISTOR" sign to fit in the horncast strip, and got my wife to paint the logo on the legshield. I was hoping to have it ready to ride on Friday night, where I could debut the scooter at the annual Spring Scoot scooter rally in Portland, put on by Twist'n'Play scooter club. The rally would basically serve as the initial road tests.

Results to follow shortly...

On Sunday I contacted Dan at Team Delta, who sold me the motor and controller. I described what was happening with the Sevcon Millipak controller and he was able to clarify things for me.

Issue 1: I could accelerate only very, very slowly, or else the system would shut down and the controller LED gave me a 9-flash error message, or "rotor position sensor fault". Turns out that I chose one of the initial controller setup parameters incorrectly. The controller uses current sensing and Hall effect feedback to servo the motor in either speed or torque mode, and I chose the speed mode when I should have picked torque. I don't have the equipment to change the setting, but Dan said he would put another controller in the mail to me on Monday with the correct setting.

Issue 2: I turn the keyswitch and I hear no "click" from the contactor engaging, and only get a 3-flash error message from the controller LED. This indicates a MOSFET short-circuit, which is internal to the controller. Dan indicated that the failure of the contactor to close confirms that this is the case. So, it's a good thing he's sending me a new controller anyway. He also mentioned that this is only the first out of about 58 of these controllers he's sold that has failed in the field.

So while I'm waiting for the new controller to arrive, I've been working on my front turn signals, using my usual medium of LEDs, acrylic plate, and 5-minute epoxy.

I figured it would be a good idea to check the function of all the major components, so yesterday I hooked up the motor, controller, contactor, throttle, and one of the batteries. I have not yet purchased the main power cables, so I had to make do with whatever spare lengths of monster cable and bits of 18 ga wire salvaged from previous LED and cold cathode lighting projects. I also haven't purchased the switches yet, so some of the final contacts were made just by touching a wire to the contactor lead (this will be a keyswitch that initiates main power) and then touching two more wires together (this will be a rocker switch to engage forward or reverse motion). This probably wasn't the safest approach, but it was good enough.

After some fiddling, I finally got the motor shaft to turn, both forward and in reverse. (My creation LIVES!!! Bwahahahaaa!!!) I spun it up to full throttle, and didn't have any problems with the BMS of my 20 Ah YESA battery cutting out due to high current draw. But keep in mind that this was under no load, after all.

Two important things I learned through this exercise:

1) I will need a separate switch to engage forward motion after I engage the main power and before I start turning the throttle. If I turn on the main power while the forward switch is engaged, this results in a controller fault message. I was hoping to just be able to turn the key, twist the throttle, and go, but I suppose pressing one more button to engage the drive isn't much different than pressing the starter button on my ICE scooter.

2) THERE IS A MISTAKE IN THE WIRING DIAGRAM that was included with my controller. http://www.teamdelta.com/products/prodimages/Millipak_PMAC_Controller_Wiring.pdf This took me a couple hours to figure out. Beware of this error if you are using a Sevcon Millipak SBPM controller. I don't know if this one-page diagram was produced by Sevcon or someone else, but the wiring is shown correctly in Sevcon's user manual. Basically, the throttle lead should connect to pin 10 on the molex connector instead of pin 11, otherwise you will get an "accelerator wire off" fault message from the controller.

Now I need to fit all these pieces in the scooter and figure out how much 4 gauge wire to buy. At $3.50 per foot for the stuff, I don't want to get much more than I'll really need.