# Curtis 1221C Controller - experience wanted



## CPLTECH (Sep 14, 2007)

In the 1997 book, “From Gasoline to Electric Power—A Conversion Experience” by Gary Powers, the author say he started with the 400A Curtis 1221C controller for his 120V Chev S10 truck (~4000# with lead acid batteries) but was a lot happier with performance when he upgraded to the 500A 1231C. I have a similar setup & vehicle.

There is confusion in the minds of many, myself included, as to what the 400A limit is limiting… battery current ?(as I had previously thought before others kept mentioning the difference here) *NO*. When looking at the last pages of the Curtis manual, the 400A or 500A refers to the *MOTOR CURRENT*. Trust me, you will appreciate any additional power for everyday driving. If you have been following the threads on the Controller section of this forum you will note the quest of everyday drivers wanting a little more power than previous controller designs have given. But it comes at a price.

Since you are looking at the Curtis line, my suggestion is to go with 144V Curtis 1231C.
The manual can be found at http://www.cafeelectric.com/curtis/Curtis_manual.pdf

94S10 1231C-8601 (144V version) 9.1” motor 20-USBattery T145


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## brainzel (Jun 15, 2009)

Thank you for your appraisement.
I certainly would take a "bigger" controller if I could, but I have to deal with the things I could afford and the 1221C was a good deal and is better than my first choice (i hope).
So the 1221C and ~120V batterypack is set and I have to live with an potentially lower performance of our car. 60mph is the target, everything above would be nice


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## TheSGC (Nov 15, 2007)

brainzel said:


> Thank you for your appraisement.
> I certainly would take a "bigger" controller if I could, but I have to deal with the things I could afford and the 1221C was a good deal and is better than my first choice (i hope).
> So the 1221C and ~120V batterypack is set and I have to live with an potentially lower performance of our car. 60mph is the target, everything above would be nice


What was your first choice? The 1221C is a rather small controller, but it should work as long as you have no hills to work with.


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## brainzel (Jun 15, 2009)

TheSGC said:


> What was your first choice? The 1221C is a rather small controller, but it should work as long as you have no hills to work with.


My first choice was a Bosch controller from a 80V folklift, witch I got with the Motor I want to use.
I have no further informations, manuals or something like that for the Bosch. Only a wireing diagram.
Thats the reason to switch and take a common controller like the Curtis 1221C.

There are no hills in my area or range of the EV 
24 meters / 78 feet height above sea level ... there are only some road holes


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## Guest (Sep 9, 2009)

I think a warning should be posted for those who are thinking of purchasing a controller, motor or any other expensive item like batteries and such before they ask and get some real good feed back. I started with a 72 volt 550 amp controller only because it had been part of a purchase of an old EV and it happened that it had never been installed so it was still new but old. With the 550 amps my little 72 volt Ghia would do 65 mph. Not shabby but with a 400 amp controller I am sure it would have been limited to about 55 and maybe even 50 mph max. I now have 96 volts and 700 amps and my little Ghia will do better than 80 mph. You will be much better off if you are patient and wait to get a controller that has more poop. You may think you will be happy with it but at 400 amps you will quickly want more. That I can guarantee. 

What is it you are converting? Photos? Is it listed in the Garage?

Pete


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## Guest (Sep 9, 2009)

Never mind, I see your conversion choice in the Garage. No, Do not go with the Curtis 1221C. You will be very unhappy. That is on the heavy side for such a low amp controller. If you can afford the lithium you can surely wait and get a good Zilla, Synkro, or Soliton controller for your ride. All have much higher amp ranges and voltage ranges that will make that beetle sing right along. 

Did you check this Electric NB: http://www.cameronsoftware.com/ev/Welcome.html


Pete


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## kittydog42 (Sep 18, 2007)

If you are in the 72V-120V range and are using lead acid batteries, there is nothing wrong with the 1221C. A project with those specs would be less than half as expensive as a setup with Lithium and a high end controller such as a Zilla, so it really is apples and oranges. Also, the wiring is so much more basic on the 1221C that it is better suited for a budget conversion. Everything (even Kelly controllers) has a niche.


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## CPLTECH (Sep 14, 2007)

Thrige-Titan TTL 200B *Compound **Wound**DC*

Will the Curtis 1221/1231C operate this motor of yours?
The manual I have shows a wiring diagram of a series wound motor.
Others with experience will have to comment…


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## brainzel (Jun 15, 2009)

First I want to thank all of you for your comments.
The Curtis 1221C was not my first choise and I know, that there are better combinations out there, but I realy have to keep my budget 
The Motor was very cheap and the Curtis a good offer, so I have to risk it, I think.

If I get the ~60mph it would be great. After a year of driving around, I probably got some money to get a better Motor and Controller and sell tho "old" one.

I took the Thrige-Titan TTL 200B to a motor-specialist and told him my plans. He tested the Motor at 120V and gave me "green light" but recommended an activ cooling.

Sadly I got no technical papers or manuals for the Motor. The company that build the Motor was taken over several times and couldn't send me anything that could help me 
If anyone here has some informations about this Motor, please let me know.


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## brainzel (Jun 15, 2009)

Does anyone knows, if my Thrige-Titan TTL 200B *Compound* Wound DC Motor would fit to the Curtis 1221C?
If not, is it possible to wire only the series wound?


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## Tesseract (Sep 27, 2008)

Very difficult to say, brainzel, how well your motor and the Curtis will get along... the wiring diagram shows the motor wired as a "long shunt compound motor", "cumulatively compounded". If you flip the polarity of the E2 (shunt) winding then the motor will be "differentially compounded".

A brief overview of all of these terms can be found in this link (Google books):

http://books.google.com/books?id=99xxCjXFbnEC&pg=PA57&lpg=PA57&dq=long+shunt+compound+motor&source=bl&ots=cszenT_F-I&sig=kvhx_9t6dfTpqvHydYxtXHzzCyY&hl=en&ei=e8IfS92XM8eXtgfzpZGgCg&sa=X&oi=book_result&ct=result&resnum=10&ved=0CCoQ6AEwCQ#v=onepage&q=long%20shunt%20compound%20motor&f=false

Basically, though, you WANT to keep the shunt winding in the circuit if for not other reason than it provides some overspeed protection, and otherwise connect the motor to the 1221C as you would a series motor.


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## brainzel (Jun 15, 2009)

OK, I thought changing the polarity of one field windung would change the direction of the motor spinning (left or right).
The "compound" caracteristic is not what makes me the headache. The better torque and speed behavior is something I like, but at the moment I don't know, if the curtis controller only works with a "pure" series wound motor ?!?


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## Tesseract (Sep 27, 2008)

brainzel said:


> OK, I thought changing the polarity of one field windung would change the direction of the motor spinning (left or right).


Changing the direction of winding D2 (the series field) will change the direction. The shunt field (E2) will not, it will either ADD to the series field (cumulatively compound - the more stable configuration) or SUBTRACT from the series field (differentially compound - potentially unstable when overloaded). Please read at Google books link I sent for a better explanation.




brainzel said:


> I don't know, if the curtis controller only works with a "pure" series wound motor ?!?


The Curtis is unlikely to care, but I'm not personally 100% sure.


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## brainzel (Jun 15, 2009)

Tesseract said:


> Changing the direction of winding D2 (the series field) will change the direction.


OK, thank you. Do you think this would work?


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## major (Apr 4, 2008)

brainzel said:


> OK, I thought changing the polarity of one field windung would change the direction of the motor spinning (left or right).
> The "compound" caracteristic is not what makes me the headache. The better torque and speed behavior is something I like, but at the moment I don't know, if the curtis controller only works with a "pure" series wound motor ?!?


Hi guys,

You definately do NOT want it differentially compound. I don't know why Tesseract even brought it up. And I don't know where the wiring diagram came from or how you could tell from the diagram which is cumulative or differential. But make sure you have it cumulative or you're likely to toast the motor.

Yes, Curtis controllers will drive compound motors. I've had a 2 terminal compound motor on a 48V, 225A Curtis for years and years. It is just a lawn tractor, so not much to worry about. But for a car, and the fact that you intend to run the motor at higher than nameplate voltage, I'd power the shunt field separately at the rated voltage. And energize the shunt field first before bring up the Curtis which would be then powering the armature and series field. That way you'll get more torque for your amps where you need it, at low speed.

Regards,

major


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## Tesseract (Sep 27, 2008)

major said:


> ...You definately do NOT want it differentially compound. I don't know why Tesseract even brought it up. And I don't know where the wiring diagram came from or how you could tell from the diagram which is cumulative or differential. But make sure you have it cumulative or you're likely to toast the motor....



Well, I wasn't as emphatic about it as you were but I did say that a differentially compound motor isn't stable! 

Anyway, I mentioned it because the polarity of each field winding is not _explicitly_ stated but the shunt field terminals are brought out separately, so its certainly possible to connect it backwards - especially if the OP thought that swapping the shunt field polarity would cause the motor to reverse direction... One way or another he's gonna find out about differentially compound motors, hopefully by reading up on it and not by watching shrapnel eject from the commutator when heavily loaded....


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## brainzel (Jun 15, 2009)

*Re: Curtis 1221C Controller - Compound Wound DC Motor*

Thanks to you both.

Reading about such technicals in two different languages and bring it all together isn't so simple for me sometimes 
It's indeed difficult enough for me to understand it in german ;-)

So changing the polarity of E1-E2 would change the direction of spinning, right?



major said:


> I'd power the shunt field separately at the rated voltage.


 Do you meen the whole pack voltage (~120V) permanently to E1-E2?
Or do I have to wire it up like the diagramm shows (controller output)?


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## Tesseract (Sep 27, 2008)

*Re: Curtis 1221C Controller - Compound Wound DC Motor*



brainzel said:


> So changing the polarity of E1-E2 would change the direction of spinning, right?


NO! Changing the polarity of E1/E2 changes whether the motor is cumulatively (good) or differentially (bad) compounded. 

As major noted (rather vigorously  ), connecting this winding wrong could result in your motor's destruction. I, myself, am not so concerned whether you destroy your motor or not as my opinion is that if you want to play with undocumented surplus you have to accept that every so often things aren't going to turn out so well.




brainzel said:


> Do you meen the whole pack voltage (~120V) permanently to E1-E2?
> Or do I have to wire it up like the diagramm shows (controller output)?


Sort of - depends on the nameplate rating for the motor voltage. If it says it's a 36/48V motor then you better not try to apply more than 48V to E1-E2. Furthermore, you need to ensure the polarity across E1-E2 matches that of D1-D2 or you'll get the same problem as above.

One last thing - if the description of this type of motor in that google books link I suggested didn't make sense to you then I strongly recommend you get rid of this motor and buy yourself a proper series wound motor instead.


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## brainzel (Jun 15, 2009)

*Re: Curtis 1221C Controller - Compound Wound DC Motor*



Tesseract said:


> ... get rid of this motor and buy yourself a proper series wound motor instead.


If anyone donates me 1800 bucks, I will think about it but at this point of conversion, the budget is already over the limit. There's no turning back at the moment ;-)
If I had a choice, I would realy think about it, so your demur is eligible.


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