# How hard do you run your Curtis 1231 on road controller?



## 9852 (Jan 17, 2010)

How hard do you run your Curtis 1231c? Here's why I ask. 
My newest conversion has a Curtis 1231c 500 amp controller in it. Now I don't really mind the whine, but I was told that I should keep the current to under 200 amps when taking off or accelerating, I feel like that is taking off at a light to slowly so I'd like to know if any one runs the amps up past 200 when taking off at a light, and if so how does the controller perform? The last thing I want us to smoke my only controller before I can get another one.
Any advise appreciated, except for "get a better controller" because I know that all ready


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## nucleus (May 18, 2012)

I think the question is why were you told this? Is it to go easy on the motor, the batteries, or the controller?

Curtiss controllers usually do best on a water-cooled mounting plate.


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## 9852 (Jan 17, 2010)

Ok, let me elabotate, when I converted my other two cars, the advice I was given was the try and keep the current down as much as I could for two reasons. 1st it was easier on the controller, after all low current = lower heat. Second it was better for range because keeping the amps down affords you more available power and more range. But both of those controllers? were lower voltage, a 72 volt altrax and a 96volt Kelly controller, I did build a couple of my own controllers pretty hard from time to time, but I knew what to expect from them.

I have never used a Curtis 1231c controller so I don't really know what to expect from it, hence the question how hard do you run your Curtis 1231c. I hope that clears it up, I'm just trying to see how well the cut back works, how much it can realistically handle, not the Curtis rating
Any help would be appreciated
Thanks


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## Duncan (Dec 8, 2008)

Hi Bill
The keep the amps down is critical with lead acid - peukert!
But with lithium it's a bit (lot) less important

IMHO if I bought a 500 amp controller then I would expect it to operate with 500 amps and if it didn't I would be pissed off and send it back

I'm running my present controller at about 48% when driving around town - but that is to avoid losing traction and I am happy to re-set to 100% (just some switches on the dash) when I'm on the track


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## 9852 (Jan 17, 2010)

Well I guess that's what I'm asking, us if the 1231c can deliver 500 amps with out letting out the smoke, I'll take a pic of my controller mounting, but it's on a really big heatsink and has a fan blowing air across the sink. I've pushed it up to about 225 amps and it does not feel hot, but I was just wondering how high I could go with the amps before getting the cutback or seeing smoke, from people who have used or are still using the Curtis. I'm going to by a zilla in a few weeks, then it won't really matter, but until then I want to keep the car on the road


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## piotrsko (Dec 9, 2007)

Get a cheap long lead electric thermometer from a dollar store and run that back into the cabin. Dont let the contoller go over 120, which may get hard in Phoenix


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## 9852 (Jan 17, 2010)

so im assuming then that 120 degrees is where the thermal cut back happens on the curtis. thats a good idea, except hell most times its 110-115 here in the summer, im not going to get to far before it gets to 120 with temps like that!

no but seriously, i should look out for around 120 degrees from the controller then, i dont think its gotten any where close to that since iv had it, so thats good info to be aware of.


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## Duncan (Dec 8, 2008)

ekthor said:


> I always thought the voltage to the motor was constant and the only variation was the amperage:


The controller effectively reduces the voltage until the motor takes the desired current

So 500amps motor at zero rpm is probably only 15v 
So 15v motor x 500 amps motor = 150v battery x 50 amps battery

As the revs rise so does the Back EMF
at 1500 rpm and 500 amps the motor probably gives 45v Back EMF

so 15v + 45v = 60v x 500 motor amps = 150v battery x 200 amps battery

at 3000 rpm and 500 amps the motor probably gives 90v Back EMF

so 15v + 90v = 105v x 500 motor amps = 150v battery x 350 amps battery

Until you get to the point where the controller is on 100% and the battery voltage = motor voltage


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## 9852 (Jan 17, 2010)

Well today is going to be a very hot day, I took the truck out to do a short 10 mile drive and on the way back I think I was getting a siren from the controller, it's still working just fine, does anyone know if the controller gives off an audible sound during over temperature cut back, I'm not sure that's what it was, but I know the sound it makes at low speed take off, this was a different sound. 
I didn't feel any noticeable difference in the controller operation, I just took it a bit easier on the controller after that

Edit: I am sure that it was the overtemp alarm, but I firmly believe that it's because my controller is air cooled and the air blowing feels like a convection oven.


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## riba2233 (Apr 29, 2015)

From datasheet:


"Thermal protection and compensation circuit provides undertemperature cutback, constant current limit over operating range, and linear rollback in over-temperature. No sudden loss of power under any thermal conditions. "

And:

"Frequency shifting from 15 kHz to 1.5 kHz at low throttle settings provides improved protection against stalled motors. "

I would say that it is possible that it reduces frequency in harsher conditions.


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## 9852 (Jan 17, 2010)

Thanks, I did read that, it also gives off an alarm to let the operator know. I think it's a combination of things happening to over heat the controller for me.


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