# Curtis controller 1221B 72-120V not working any more



## miko81 (Apr 2, 2012)

Hi guys,

I have big problem, please help me.
Yesterday I was driving with my car and something smell wired, so I have check my battery's and it was smoking from one battery so I drove car home and disconnect this battery and make battery pack without that battery. When I try to drive the car didn't go, I was pressing gas pedal but nothing. I have check everything and everything is connected right, so i took out controller and took it to garage. 

here is picture off my wiring


before error:
when I connect battery to controller it shows 75V on battery - and on battery + and motor +, when I pres gas pedal it shows 75V on battery + and motor + and motor -.

Now:
when I connect battery it shows 75V on battery - and battery + and motor +, but when I press gas pedal it dont showe nothing on motor - and battery + and motor +.

you can see ewerything on video.

please help me


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## Ziggythewiz (May 16, 2010)

So what voltage were/are you running? Shouldn't the voltage have changed from before -> after if you removed a battery from the circuit?


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## miko81 (Apr 2, 2012)

Ziggythewiz said:


> So what voltage were/are you running? Shouldn't the voltage have changed from before -> after if you removed a battery from the circuit?


Before I was driving on 72V (it was around 78V) then on weekend I add one extra battery and voltage was 86V that battery was bed one and that it is battery that it was smoking and i have take it out from pack. But I have test controller in garage on 76V, 83V 93V 100V and nothing


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## frodus (Apr 12, 2008)

Is there fuse between battery and the controller? 

Where's your contactor and precharge resistor?

One thing I can't tell because the wires are in the way.... is how you have the Enable pin and Throttle wired up. What value potentiometer is it? It looks like you're using it as a 3-wire throttle.


Draw a schematic and post it... it's difficult to tell how you have it wired.


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## miko81 (Apr 2, 2012)

this on video is testing with charger.
there is no fuse on this video and there is no precharger and contactor on video but in car i have it (in car i dont have fuse).
I use tree pin 5 kohm pothenciometer, wiring is like this:
pins on controler 
1- connect to battery +
2- connect to pothenciometer so it create from 0-5k ohm
3- connect to pothenciometer so it create from 0-5k ohm

third pin on pothenciometer I have connect to battery -

when I seen that this controller dont work I take my another curtis controler 1204 36-48v and connect it the same way as this one but i lover voltage to 48V and he was working.


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## frodus (Apr 12, 2008)

*ALWAYS FUSE.* It protects you, the controller and the batteries. I can't stress this enough. 



> Draw a schematic and post it... it's difficult to tell how you have it wired.


Explaining it via text doesn't help much.... please post a schematic.



A POT has 3 connections, but the schematic from the Curtis manual is 2 wire (0-5V is an option, and IIRC, it's a different controller part number)

Take the middle (wiper) and wire to pin 2. Take the one closest to "off" when you rotate it and wire to pin 3. Leave the other disconnected. It's a 0-5k throttle, you don't need B- connected to the POT at all.

Read the troubleshooting area of the manual:
http://www.curtisinstruments.com/index.cfm?fuseaction=Datasheets.downloadmanual&prodid=65


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## miko81 (Apr 2, 2012)

ok, I dont know how to draw scheme so I drowe it on picture. When I connect another controller on this way he works, this one was allso working connected this way but before, yesterday nothing.



I have bouht it used and it was working fine on 72V, I dont know maybe I needed to reprogram it when I was connecting higher voltage??


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## frodus (Apr 12, 2008)

Before you do anything more, PLEASE fuse the controller.

Remove the ground wire from the POT, you do not need it. I realize that may be how the other is wired, but you do not need it. Wire it like in the curtis manual, just use 2 wires, they know what they're doing.

Check the resistance on the POT between the outermost two pins. It should read 5Kohm. If it doesn't, the POT might be bad.

If that doesn't work, wire pin 3 of the controller to where the purple wire is attached to the pot. You may be reading 5K-0 right now, in which case it may cause shutdown. You want the pot to read 0-5K increasing as you turn the throttle.



What kind of motor is it connected to?


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## miko81 (Apr 2, 2012)

ok, I will wire it tomorow (now it is geting night). fuse goes on + terminal?


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## frodus (Apr 12, 2008)

RTFM
http://www.curtisinstruments.com/index.cfm?fuseaction=Datasheets.downloadmanual&prodid=65

It's all in there and you need to be be wiring according to that manual. It shows exactly how a fuse, contactor, precharge, throttle, etc are wired in.


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## miko81 (Apr 2, 2012)

hi

I have wire it like in manual:


and here are results:
-pothentiometer, on pin 1 and 2 when I turn it goes from 0-5k ohm. On pin 2 and 3 goes 5-0k ohm. So I connect pins 1 and 2 to controller pins 2 and 3 (pin 3 from pot didnt connect any were).
- battery pack voltage 77,8V. Controller voltage 0V, when I turn on precharge it slowley start rising voltage on B- and B+ terminals on controller then I turn on contactor and voltage on controller is 76V.
-mesuring voltage on terminal B- and KSI it is 76V.
-turn POT 2k ohm, voltage on B+ and M- 0V.
-mesuring pins 2 and 3 on controller it shows 2k ohm 

Acording to user manual trubelshut, my controller is defectiv


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## frodus (Apr 12, 2008)

you don't have it connected to an actual load?

You need to put a load (throw a 100W light bulb on there). A multimeter may not be able to measure anything.


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## miko81 (Apr 2, 2012)

I dont have bulb dc, so i connected motor but nothing hepens, no power to motor.


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## McRat (Jul 10, 2012)

Normal light bulbs for your house do not care whether you feed them AC or DC. I've run them up past 300vdc when testing stuff, and they start to glow at about 50v IIRC.

Their life at 300v isn't long.


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## miko81 (Apr 2, 2012)

I have try with bulbe but nothing. 
I dont know does this mean that my controller is dead, did anyone have problem with Curtis controller


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## mk4gti (May 6, 2011)

I had a similar problem with a cursit. There was something loose inside, sold it for parts.


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## miko81 (Apr 2, 2012)

hi mk4gti

did you even open it to see what is hapened??


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## mk4gti (May 6, 2011)

No - I didn't get the required performance out of it and my heart was set on something else.

There are some videos of a few lads opening up theirs on youtube. I had a quick look and decided to not opening it. It looked too complicated for me at the time.

I hope you can fix your controller.


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## miko81 (Apr 2, 2012)

mk4gti said:


> No - I didn't get the required performance out of it and my heart was set on something else.
> 
> There are some videos of a few lads opening up theirs on youtube. I had a quick look and decided to not opening it. It looked too complicated for me at the time.
> 
> I hope you can fix your controller.


will see,
maybe I will offer it first for sale and if not sale it I will need find someone to fix it if it is posible.


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## miko81 (Apr 2, 2012)

ok since i dont know how to fix it, Iam selling it


http://www.ebay.com/itm/251194332907?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

avalible on marketplace


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## EVfun (Mar 14, 2010)

A Curtis 1221B 120 volt controller is over 15 years old, so its failure is to be expected. These where not top of the line hardware, but solid workhorse hardware from a company that mostly does lower voltage forklift electrical hardware. I've blown one up spectacularly shot the end cap down the street and sent flames 18 inches out the end. They are really sized for cars under 2500 lb. They don't monitor the capacitor temperature of freewheel diode temperature. They require a cooling system and make the user design it. 

For a on-road EV I would recommend either a Soliton or Zilla controller. In either case I would recommend liquid cooling. The lowest cost fix would be a new Curtis 1231C controller, pretty much bolt in but a little bigger case. No wiring changes would be required so it would be the easiest too. Still, I recommend the Soliton or Zilla as they are more robust and offer more peak torque and power.


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## miko81 (Apr 2, 2012)

Finally I have open it, here are pictures.









did anyone open Curtis ever and have same problem??


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## Ziggythewiz (May 16, 2010)

Cool pics. Good to see you can get to stuff. I've heard some curtis controllers were potted inside blocking any access.

Doesn't look too terrible. Are the traces on the other side intact?


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## Weisheimer (May 11, 2009)

miko81 said:


> Finally I have open it, here are pictures.
> 
> 
> 
> ...


Better question...Did anyone ever open a Curtis and NOT have the same problem?

Actually they are probably more reliable than many others.
The DC bus caps are probably a bit dried up, so consider replacing them all.

Can you read a schematic? Here is a link to Otmar's schematic post.
You'll want it if you are going to pursue this further.

http://www.cafeelectric.com/curtis/curtisschematic.pdf

Here is the link to the controller manual, which may have been posted earlier, but I am going to post it in case it wasn't.

http://www.cafeelectric.com/curtis/Curtis_manual.pdf

and yes, others have found this and more when they opened up the controllers...

From what I can see, it looks like you had pack voltage cross into the throttle pedal input. That might not be such a tough fix.
I usually put a board that looks like that in a bath of alcohol and clean it with what I know as an "acid brush" and then let it dry thoroughly.

Are you comfortable going further with the repair?


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## PStechPaul (May 1, 2012)

For cleaning my PCBs, I use alcohol and an acid brush (or toothbrush) to remove solder flux residue. Be sure to snip the bristles short so it scrubs better. But then I spray the entire board with a detergent like Simple Green, and then scrub it under hot water and rinse thoroughly. Finally, I use a heat gun to dry the board. Be especially careful to blow hot air under SMT components (especially ICs), and it may be best to remove socketed ICs before cleaning. Some people suggest using a dishwasher. Most components can be fully immersed. The only exceptions are things like speakers or beepers or some adjustment potentiometers, and they can usually be sealed with a bit of tape or silicone sealer which can be removed after cleaning.

There are repair kits that can replace damaged tracks and through holes using strips of copper or silver ink and copper eyelets.


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## miko81 (Apr 2, 2012)

tnx guys for advices.

Yes it was pain in the ass to open it, I was more afraid to brake something than it was difficult to open it.

I was checking it and only on this was something burned out. 
Yes I will going further to fix this, if it is possible.

I dont know electronic so I will take it to someone else.

If it cant be fixed can I buy this board separatly?


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## ElectricVintageCars (Oct 30, 2021)

miko81 said:


> Hi guys,
> 
> I have big problem, please help me.
> Yesterday I was driving with my car and something smell wired, so I have check my battery's and it was smoking from one battery so I drove car home and disconnect this battery and make battery pack without that battery. When I try to drive the car didn't go, I was pressing gas pedal but nothing. I have check everything and everything is connected right, so i took out controller and took it to garage.
> ...


I have the same problrm, i think Curtis is a shit, my controller was working only 5 mounts. Noobady cant told me nothing, when i opened the m...fucker is smell like a dog, bud is imposiblle to rebuild all parts and i have crap for 700 $. Never again company with Bulgarien products made in USA its better to take from China is the same sh... for 300$ or 1000 for a full kit.


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