# Blowing KLK fuse...



## JSRacer (Jun 22, 2008)

Well the maiden voyage was awesome and I'm still grinnin' but there is also some problems. 

I posted this over at my thread so I apologize for the double post. 

http://www.diyelectriccar.com/forums/showthread.php/1993-eagle-summit-van-car-16034.html?p=101034

Here's the problems and questions I have if any of you can help. 

1. We are still blowing our KLK 20 amp fuse. But after blowing a couple we began to try to isolate the problem and narrowed it down to the DC/DC converter. If we take the DC/DC converter clear out of the picture, we are good to go. Soon as the DC/DC converter is hooked up we're back to blowing fuses. The fuse blows when the ignition switch is turned on / when the primary contactor closes. We've checked wiring over and over and everything matches our schematics. Any ideas?

2. We tried to charge the pack with the Zivan charger and tripped a 15 amp breaker in the box after about a minute. Does the Zivan need a 20 amp or 30 amp breaker? 
Also, the Zivan is noisier than I imagined it would be. There is a noisy arcing type sound I would guess has something to do with the fact that it's a high freq charger. Is this noise anything to be concerned with?

Again, please forgive me for double posting but I'd like to reach as many of you as I can so that possibly tomorrow we can have a solution to these issues. 

Thanks in advance!!!


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## etischer (Jun 16, 2008)

does the dc-dc converter need a precharge? Maybe you can put a slower blowing fuse in, I know KTK is a fast blow, and FNQ is a slow blow. Not sure what a KLK is, but if that is what's called for, the fuse is probably not your problem. I imagine dc-dc converter would need precharge circuit.


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## JSRacer (Jun 22, 2008)

This is my first conversion and I have a ton to learn. So, I'll ask, what is a precharge circuit?


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## JRP3 (Mar 7, 2008)

You might want to read through this.
http://www.alltraxinc.com/files/Doc120-046-A_TN010-Contactor-Fuse-Diode-Lessons-Learned.pdf


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## tj4fa (May 25, 2008)

Or check out information posted in this thread...

http://www.diyelectriccar.com/forums/showthread.php/1993-eagle-summit-van-car-16034p9.html


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## ice (Sep 8, 2008)

i think a pre-charged circuit is that limits both peak DC link and peak AC input line current to a desire magnitude.


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## JRP3 (Mar 7, 2008)

Not exactly. It's a resistor that slowly charges the capacitors in your controller so they don't get slammed with full pack voltage when you turn it on. Read the PDF I linked to above.


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## ice (Sep 8, 2008)

but the function is the same process, correct me if I am wrong...


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## JRP3 (Mar 7, 2008)

Well in this setup it is only limiting the speed of voltage rise in the capacitors. The caps still reach the same voltage they would without the precharge, just more slowly so as not to damage them. Current is not involved or is minimal.


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## bblocher (Jul 30, 2008)

JSRacer said:


> Well the maiden voyage was awesome and I'm still grinnin' but there is also some problems.
> 
> I posted this over at my thread so I apologize for the double post.
> 
> ...


I guess I missed that part about where the KLK 20 is connected? Is this between your traction pack and the DC/DC converter?

Which DC/DC converter are you using? I know on my IOTA 45 that I can disconnect the 12v output side and the converter does nothing (near zero amp draw). Even with my lights on and the vacuum pump running the DC/DC is still only pulling a little over 1 amp. If you're still blowing the fuses with no output it can't be the converter pulling too many amps.


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## JSRacer (Jun 22, 2008)

I've found the culprit so I'd like to follow up on this! Along with our instructions with the Astrodyne DC/DC converter through EV America there is some good information that we overlooked. Imagine that?  

It states that a diode is required for voltages of 152V and above. Hmmmm..... We're at 120V or so with our system. "Should we take it out?" Well, we took the diode out and it works beautifully now and we're no longer blowing KLK 20 amp buss fuses. Problem solved!


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## Greenflight (Sep 13, 2007)

JRP3 said:


> Well in this setup it is only limiting the speed of voltage rise in the capacitors. The caps still reach the same voltage they would without the precharge, just more slowly so as not to damage them. Current is not involved or is minimal.


FYI- I'm pretty sure a precharge circuit isn't just there to protect the caps. After the precharger has brought the caps up to pack voltage, there is no difference in potential across the contactor, so this keeps it from arcing when it closes. And that's just good for everyone.


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## JRP3 (Mar 7, 2008)

Good point.


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## JSRacer (Jun 22, 2008)

Greenflight said:


> FYI- I'm pretty sure a precharge circuit isn't just there to protect the caps. After the precharger has brought the caps up to pack voltage, there is no difference in potential across the contactor, so this keeps it from arcing when it closes. And that's just good for everyone.


So is removing the diode a bad idea under 152V? Sorry I'm kinda slow and I'm not sure if this was directed towards me?  Also, is the diode that I'm referring to called a precharge circuit? Just a little lost with the last couple replies.


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## JRP3 (Mar 7, 2008)

The precharge resistor and diode are two different things, and both should be used as far as I can tell. From Alltrax "lessons learned" PDF:


> • DIODE is a protection device across the
> contactor coil. The contactor coil is a magnetic
> device. When the contactor is turned off, the
> magnetic field collapses causing a “voltage
> ...


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## JRP3 (Mar 7, 2008)

Note that Alltrax systems are 72 volts and under, and they think these are important elements to include. The "Lessons learned" PDF really explains it all fully.


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