Curtis Controller 1221C

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KDRYAN
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Curtis Controller 1221C

Post by KDRYAN » Sun, 21 Dec 2008, 14:24

Hi All
I have just fitted a Curtis 1221C controller to my conversion and have a strange problem. This is a 120volt @400amps unit. The problem is on acceleration from a standing start or rolling from a slow start the controller is limiting the curent to 100amps output and increases to above 300amps as the motor speed increases.

I previously had a Alltrax controller @ 72vdc fitted and I was able to obtain 300amps from standing start with amps decreasing as motor speed increased, which I believe is the norm.
Has anyone else seen this problem or any suggestions to the cause of this.

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Electrocycle
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Curtis Controller 1221C

Post by Electrocycle » Mon, 22 Dec 2008, 02:00

are you definitely measuring the motor current and not the battery current?

What you're describing is about what I'd expect the battery current to do.

Is the performance ok, or is it very slow to take off?
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KDRYAN
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Curtis Controller 1221C

Post by KDRYAN » Mon, 22 Dec 2008, 02:55

Hi Electrocycle

Yes, I am measuring the battery current (between battery and controller) and yes the performance is very slow from stsrt to approxamately 20 to 25kph. After that the acceleration is very good. On a modeate drive of about 10km today the controller got hot to the point that the audable alarm started to sound. The motor at this point remained only luke warm.

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Kim

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Electrocycle
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Curtis Controller 1221C

Post by Electrocycle » Mon, 22 Dec 2008, 03:37

ah ok.
Do you know what the controller current limit is set to?

The battery current will be much lower than the motor current to begin with, evening out at higher speeds.

If you're at full throttle at takeoff, and the current limit is 400A, it might only take 10% duty cycle to push 400A into the motor, so you'll only draw around 40A from the batteries.
As the motor speeds up it takes more voltage to maintain the 400A current limit, so the duty cycle increases.
With 50% duty cycle you'd be drawing 200A from the batteries, 100% duty cycle 400A from the batteries, and then as the speed increases further the motor will start to draw less current.

I expect that the controller is set to 300A current limit, and probably has the throttle response set quite slow - so it'll be ramping up the motor current gradually.
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KDRYAN
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Curtis Controller 1221C

Post by KDRYAN » Mon, 22 Dec 2008, 05:19

Thanks for the reply, I will adjust the controller for max current(400amps) and max acceleration rate and see what the results are. The settings are factory standard at present so it is unknown to me there present values.

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Kim

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Curtis Controller 1221C

Post by Taffy » Mon, 22 Dec 2008, 05:47

Hey Kdryan,
We had this problem using the controller on our race car. Though we had a "max" of 250A, but we did pull 270A on a few occasions. Even winding the current limit out and the throttle response fully up we could not break traction on a 188kg vehicle. If you do manage to find a boost i would be very interested.

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Curtis Controller 1221C

Post by Electrocycle » Mon, 22 Dec 2008, 16:44

most controllers still limit the ramp up even when set to maximum response, but I'm not sure how much the Curtis does.

Geoff's go kart with the Alltrax controller and Perm132 motor certainly takes off very hard though!
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