# Welded contacts



## frodus (Apr 12, 2008)

Its probably due to the huge inrush current that the coil has..... wonder what it draws on inrush? what are the contacts rated?


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## Tesseract (Sep 27, 2008)

frodus said:


> Its probably due to the huge inrush current that the coil has..... wonder what it draws on inrush? what are the contacts rated?


Inrush is quoted as 3.8A over the 9-36VDC operating range but at 12VDC I've seen as much as 8A. The aux contacts are rated for 2A/30VDC and they are "wet" contacts, which means they need a minimum amount of current to operate (yes, there is such a thing), in this case, 100mA.

So, no, the aux contacts are not rated to operate another EV200, nor are they suitable for a signal-level input. In other words, they are pretty much useless.


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## frodus (Apr 12, 2008)

I would think they're only good for signal enables and stuff like that. Not high current and inductive loads.


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## etischer (Jun 16, 2008)

The aux contacts are not used to energize the coil, it is used only to hold the coil. The Ignition switch energizes the coil and deals with the coils inrush. The Aux contacts on the main contactor are not subjected to inrush because the coil is already energized when they close. (Aux contacts only close after the coil is energized)

The holding current of the coil is 0.13A which is above the min, and below the max. I'm not exeeding the rating of the Aux contact.


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## Dave Koller (Nov 15, 2008)

Eric:

Are you getting a back rush from the Pre-charge contactor coil WHEN the main kicks OUT _not_ in ? ( well at least the time that it welded the thing ) - Then the next time with the weld - You have a problem!


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## etischer (Jun 16, 2008)

The ignition switch would be the part that breaks the 12v circuit, and de-energizes the coil. The coil also has the economiser and they say it has 0V back-emf (no diode protection needed)

The Aux contact on the EV200 can only open after the coil has already been de-energized. 

Perhaps I just got a fluke failure. 





Dave Koller said:


> Eric:
> 
> Are you getting a back rush from the Pre-charge contactor coil WHEN the main kicks OUT _not_ in ? ( well at least the time that it welded the thing ) - Then the next time with the weld - You have a problem!


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## Dave Koller (Nov 15, 2008)

Wonder if you put a diode/resistor back bias across the contacts - just for luck! Could be a fluke BUT something had to cause it. Did you see the contacts up close and was the weld in center or edge? Another - er, just for fun would be to "test" the coils and see if you have some failure in the "economiser' that could cause this or a loose wire to that "economiser" circuit that bounces it out once in a while... At least so there is no chance left to become a "Toyota" problem - LOL ( we DIYers think those things out better - I hope )

Use the scope and pound away at it for a bit to see - maybe pull pack off just test key and low volt side.. I am one not to let it go - will test the crap out of it cause by all rights it should not do this ( circuit looks good!)- BUT like you said - it is another case of diode ( or "economiser" ) VS Not ! It acts like NOT !


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## etischer (Jun 16, 2008)

Kilovac is sending me a warranty replacement. That is my next thought, pwm failure in the encomizer. The contacts are potted so I can't see them without cutting it open. 






Dave Koller said:


> Wonder if you put a diode/resistor back bias across the contacts - just for luck! Could be a fluke BUT something had to cause it. Did you see the contacts up close and was the weld in center or edge? Another - er, just for fun would be to "test" the coils and see if you have some failure in the "economiser' that could cause this or a loose wire to that "economiser" circuit that bounces it out once in a while... At least so there is no chance left to become a "Toyota" problem - LOL ( we DIYers think those things out better - I hope )
> 
> Use the scope and pound away at it for a bit to see - maybe pull pack off just test key and low volt side.. I am one not to let it go - will test the crap out of it cause by all rights it should not do this ( circuit looks good!)- BUT like you said - it is another case of diode ( or "economiser" ) VS Not ! It acts like NOT !


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## Dave Koller (Nov 15, 2008)

By now I am sure you saw :
Posted by Coulomb :

http://www.diyelectriccar.com/forums/showpost.php?p=170629&postcount=42

Any little thing wrong on there and - well maybe !


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