Greetings Folks.
I have a an Electric Yale,
Mode# ERC050JAN36SE083
Serial# 480353
It has recently acquired a really nasty issue. As you start to pull away everything is fine. Then suddenly it jumps to FULL SPEED regardless of the pedal setting. This instantly spins the wheels, generates a massive jerk, and then it stops.
Further application of the pedal sometimes results in a repeat but often nothing happens at all. You need to turn off the ignition, return the direction lever to neutral, turn the ignition back on reselect the direction and try again. Often with an identical result.
Vague associations include steering all the way to a stop or going uphill is rumored to increase the incidence. Driving over very minor floor cracks has also been mentioned as a precipitator of this behavior. Once it seems to get in this "mode" it may behave this way continuously. To the point of being completely non-usable.
It has slowly developed this trait over a month. To where it is completely unreliable now.
I have carefully gone over all the signals going into the EV-100 screw terminals. They are just as expected.
I have gone visually over everything I can see - no obvious loose or frayed wires.{dang}
It should be noted that you can press the pedal down until motion is just occurring and hold it right there. The FL will start to roll getting perhaps six inches and with no bumps or further pedal motion have one of these "events" occur.
Suggestions for further investigation?
Showing items 1 - 5 of 5 results.
I would go with the "stuck on" scr, but there may (or may not) be something causing the "stuck on" (or more properly, failing to turn off) SCR. likely causes include a pin (or larger) hole in the insulation sheet under the number 1 scr, a bad number 2 or 5 scr or leakage in the 3&4 recs/diodes, and/or the insulation sheet under the heat-sink that the number 3&4 recs are mounted to. This is why the first check should be for leakage to the frame from any of the power cables. any leakage that results in a reading of less than 100k ohms should be repaired FIRST, then go looking for other causes.
when you say "Leads to the SCRs are good" are you saying that you checked them for shorts to the frame and found NONE? (some is normal in the m-ohm scale), especially with a battery installed and plugged in)
Thanks for the response bigGlittlestar.
I thought that too, especially since this lift seems to have an added electronic throttle.
I put a scope on the the throttle signal and while it has lots of SCR noise riding on the throttle signal the average throttle voltage seems to behave just fine. It never mysteriously drops to zero(full speed) like I was hoping.
Its been a few years since I had my hands on an electric, but it sounds to me like an accellerator pot issue.
Thanks Edward.
Battery is OK
Leads to the SCRs are good.
Yes, does it with drive wheels in the air.
The brushes look adequate.
I haven't checked the cable leakage yet.
Does the speed controller go thru any kind of staged increase?
I ask because once full speed is hit, (instantly after the same brief normal period), the controller dumps the main contactor.
This seems consistent with something causing full speed to occur followed instantly by the controller maybe recognizing an out of control situation, like a stuck ON SCR, and dumping the contactor. A puff of smoke always leaves the contactor after an event. What I'm saying is this whole event cycle is extremely repeatable. Accelerator depressed only until motion starts - normal PWM whine starts. This continues for about 3 seconds followed by full speed - bang! - no speed.
you may have more than one problem tied together.
First, get the battery checked under load. then test for "shorts to frame" on all the power cables. if you have less than 100k ohms on any power cable to the frame, you will need to trace and fix that short.
you may also have a bad scr or diode, or wire connection to the gate lead of an SCR.
does it do it with the drive wheels in the air? have you checked the drive motor brushes?
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