# welded contactor fault curtis 1239/ac-51



## zapyourrideguy (Oct 25, 2012)

I got a code 38 on my spyglass "welded contactor fault"
It was a few hours after a fairly hot drive. 104 outside temp. The next morning I checked the contactor and it was closed with no power to the system. tapped it with a hammer and problem solved. This is a system set up "by the book" from HPEVS using the proscribed components and wired per their diagram.
My question is should I replace this contactor? It is the tyco sold with the package. Anybody have similar issue?


----------



## evmetro (Apr 9, 2012)

zapyourrideguy said:


> I got a code 38 on my spyglass "welded contactor fault"
> It was a few hours after a fairly hot drive. 104 outside temp. The next morning I checked the contactor and it was closed with no power to the system. tapped it with a hammer and problem solved. This is a system set up "by the book" from HPEVS using the proscribed components and wired per their diagram.
> My question is should I replace this contactor? It is the tyco sold with the package. Anybody have similar issue?


I have not had this problem with any of the HPEVS builds that I have done, but I went through it with a DC build that I did awhile back. I replaced the contactor with a heavier one, and no more problems. 

Although I am not certain, I understand that once the contactor has welded like this, the contacts are damaged, even if banging it on a table unwelds them. I have one that was welded a couple times, and have it in place in a lower current circuit on one of my builds and am monitoring it to see how it holds over time.

I would just replace your contactor with the same one, but make sure that there is not a reason why the contactor welded, such as having it connect or disconnect under load. A bms HVC signal that deactivates your contactor coil because of too much regen could cause this, or restoring coil current while driving after a fault circuit had it disconnected.


----------



## PZigouras (Jun 5, 2010)

I have been running two Tyco EV200 contactors in series on my DC system for years. It seems like overkill, but one of them actually failed last year.

I also did the same on my HPEVS system, although I don't think it was really necessary.

One thing I have to say about the old Curtis SW-200 contactors is that I have never seen one weld shut. Most people no longer use them, due to the fact that no one like open contacts... everyong prefers a sealed unit. But I have used them to break 600A at 320V DC without welding.

The next best thing would be the Gigavac MX-12. They will run at 400 degrees (F) and have been shown never to weld shut (according to Gigavac). They are also completely sealed, like the Tyco units.


----------



## Tesseract (Sep 27, 2008)

zapyourrideguy said:


> I got a code 38 on my spyglass "welded contactor fault"
> ...
> I checked the contactor and it was closed with no power to the system. tapped it with a hammer and problem solved. ...


This is invariably caused by closing the main contactor before the capacitance inside the controller is (nearly*) fully charged. I don't know exactly how precharge is handled in Curtis inverters, but if it is a simple timer and the precharge resistance is too large or the capacitors have drifted upward in value - something electrolytics are prone to (typical tolerance is +80/-20%) - then that would be the most likely cause. Otherwise, closing big contactors when there is no voltage difference across the two contacts (ie - precharge to 100%) can result in weak welding of the contacts as soon as a high current flows through them, but this mainly afflicts vacuum contactors in low-vibration environments (Kilovac and Gigavac EV contactors are gas-filled and, of course, operate in a high-vibration environment). And speaking of gas-filled, the typical gas in this application is hydrogen and if it were to leak out then that could result in weak welding of the contacts, too. 

Regardless of the proximate cause (which should be determined by watching the voltage at the inverter side of the contactor during precharge and making sure the contactor doesn't close too soon [or too late]), you need a new contactor.


----------



## PStechPaul (May 1, 2012)

If the contacts only tack welded, you can likely burnish them with a file and they will be OK. It's also possible that the springs have weakened so that there is less force pulling the contacts apart. The cause was probably a poorly timed closure before capacitors were fully charged, as mentioned, and that problem should be fixed.


----------



## zapyourrideguy (Oct 25, 2012)

This contractor was not welded closed because it only took a very light tap with a hammer to open them. It has been trouble-free since. My dealer for the system said that the contacts turn each time they open so you may never have the problem again, but he said make sure that you check that all connections are clean and bright.


----------



## mizlplix (May 1, 2011)

I understand that there is a fixed 2 second interval for the precharge to happen. It is plenty time to do so if you are running a pack with in the Curtis voltage recommendations (108 VDC or lower) My controller was set up for PB/Acid batteries and 108 volts Max. It would shut down if 130 volts were exceeded.

I for one was running a 130 volt pack. (38 cells) It was arcing a little every time I turned the car on. One day it registered a "welded" fault. Yes, a small tap opened it, but there after I always got an "oxidized contact" fault. 

I replaced the contactor even though it still worked. No more faults.

I was also told to run a ceramic resistor 47 Ohm 5 watt across the points to fix this. I could leave the precharge on or off at my decision. I left it on.

The only thing is that I must turn off the pack switch every time I parked or it would eventually drain the pack.

To date there is no firmware update to increase the precharge time. That would be the simplest solution.

BTW: the TYCO contactor is a sealed unit, one can not file the contact points without a great deal of trouble.


----------



## PStechPaul (May 1, 2012)

I'm working on an automatic charge surge and capacitor discharge system for the EMW charger, which could be adapted to other chargers:


----------



## zapyourrideguy (Oct 25, 2012)

Thanks for your responses.
So are you saying the pre-charge circuit sold with the controller from HPEVS is not adequate to the job of keeping my contactor healthy? 

It is a precharge resistor and relay (potter-brumfield) wired per their diagram. I am running 144 volts on a system designed for that voltage. The car has about 8000 miles on it with this system.
I am not trained in electronics so bear with me.


----------



## mizlplix (May 1, 2011)

All I was saying was that I was running way above the designed precharge voltage. My controller has an internal precharge circuit. An added external resistor was recommended to me and has worked for 3 years.

I suggest maybe that if you slightly increase the value of the resistor (making it pass slightly more current) it would help your problem.

Those contactors are not cheap.

Miz


----------



## major (Apr 4, 2008)

mizlplix said:


> I suggest maybe that if you slightly increase the value of the resistor (making it pass slightly more current) it would help your problem.
> 
> 
> Miz


Hi Miz,

Wouldn't decreasing the ohmic value of the resistor increase the current?

major


----------



## mizlplix (May 1, 2011)

I was referring to the wattage value but failed to be clear. my second comment was referring to what I was trying to accomplish.

A sign of age maybe?

Miz


----------



## PStechPaul (May 1, 2012)

I would think that a simple circuit to read the voltage difference across the precharge resistor and the close the contacts when it is low enough to be safe would be at least as easy and cheap to implement as a timer and would accommodate any value of capacitance. It may not even require the electronics I show above, but it is not as easy as putting a 240 VDC coil across the resistor and having it pull in to insert the resistor. It needs to have the resistor in the circuit as soon as power is applied and then close the contacts when ready. So that means NO contacts which close when ready. Perhaps a 240 VDC coil relay which drops open when the voltage drops below holding voltage, and then its contacts would pull in the bypass contactor using the mains voltage or the voltage across the capacitors.


----------



## mizlplix (May 1, 2011)

It would have been nice if Curtis allowed the user to simply increase the precharge interval. (Instead of locking it up like a run away cow).

Miz


----------



## zapyourrideguy (Oct 25, 2012)

I replaced the tyco positive contactor with a gigavac through HPEVS.
that did not solve the problem. i then found that my negative contactor was not closing preventing precharge. I replaced that one with the old tyco and voila problem solved. for now.

When I had the welded contactor fault that I cured with the tap of a hammer, I was assuming it was the positive contactor (controller side) but I solved the problem by replacing the negative contactor controlled by the Orion.
Is the controller capable of detecting a welded contact on the negative contactor? (its controlled by the Orion) It seems a welded contactor on the bms side would just look like a pack ready to go. but the 1239 and the Orion are coupled by CAN and if so that explains everything.

Should I go ahead and replace the second Tyco?

It sure is great to have this forum and it sure is fantastic to be able to call tech support at HPEVS and my dealer thunderstruck motors for help and talk to live people.


----------

