Moar Power

I have some good news and some bad news.

I’ll start with the good news because there is plenty of it.  Last Thursday, we were reflecting on the fact that our go kart was basically mechanically done, which only left the realization that we needed to hook up some batteries* and BAM–we’d have a working kart (*maybe it was a little bit more complex).  Shortly after, we had an electrical schematic:

Wiring for the Kelly controller was pretty straightforward

Wiring for the Kelly controller was pretty straightforward

We started the wiring process on Friday afternoon at about 1 pm.  It wasn’t terribly exciting for the purpose of this blog–lots of soldering and heat shrinking (which is actually, in fact, one of the finer activities in life).  By the evening, we had basically everything ready to go, except the batteries were not charged, which unfortunately took more than a couple of hours to rectify.  In the meantime, we got some more laser cutting and the precharge circuit done.  I forgot to mention that we have named our kart Zoran (the Norse god of speed).  We’ve got a logo and everything:

We are both really happy about how the wood switch plate turned out.  Our Kelly controller has the capability to spit out error messages through an LED, so below the silver switch, there is an indentation in the back of the plate that lets the LED flash through the wood.  So classy.  Maybe I will put up a video later.  Here are some updated pics of the kart:

Anyways, speaking of error codes…here’s the bad news…

We had everything wired up, so we turned on the switch to the controller.  When working properly, the LED flashes 4 times and then remains turned on.  No such luck for us–the LED flashed 4 times and then repeated a 2 flash-4 flash pattern, which translates to “Throttle error at power-on: Throttle signal is higher than the preset ‘dead zone’ at Power On.  Fault clears when throttle is released.”  Unfortunately for us, our first instinct was to take the throttle apart, which in retrospect was not the greatest idea.  We were under the impression that our throttle was an extension of a potentiometer, but nope, it was just a little hall effect sensor.  It wasn’t glued in either–not good.  Our solution was the change the limits that the controller would read for the throttle at rest and at max by checking the voltage read by the throttle itself.  Tampering with it led to inconsistent values, though, and the motor would not run after moving the kart around excessively even though we reglued the sensor in.  Sad face : (

But hey!  It’s not all bad news!  It was 4 am and we were going to ride the kart one way or another.  The throttle would work for a little bit before failing, so we had the controller set up to read values from 2 – 3.5V and hopped on the kart.  Here’s Nelson on one of his first runs:

We didn’t push it too hard in N52 because we didn’t have enough space to go at top speed for extended periods of time, so the video is basically proof of concept.

We should have a working throttle by this week.  Potentiometers, man.  That’s where it’s at.

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