# How to chose contactor



## spoland (Aug 9, 2012)

Hi,

I'm planning on using a Kostov K9" 220V and a Soliton Jr for a conversion. The Soliton has a built-in main contactor, but I want to use an external contactor to break the batteri circuit in the middle to remove the voltage from the engine compartment.
According to the Kostov specs it has an sustained current of 180A when delivering 32 kW at 220V while the peak current is 500A giving 78 kW.
Can anyone advice me on how to choose a contactor for this? I saw a 600A contactor which was 2,3 kg, enormous! Or will a 200A contactor be sufficient since the peak current will occur very selldom?
I guess the contact voltage will not be an issue since the circuit will be open when the contactor closes and opens, and no voltage will be present over the contacts (unless a emergency break is done while driving).

/ Peter


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## Roy Von Rogers (Mar 21, 2009)

This is what you need, but you may also look for a BRB (big red button) manual disconnect switch instead.

http://www.ebay.com/itm/Kilovac-EV2...t=BI_Control_Systems_PLCs&hash=item43af8d50ee

Roy


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## spoland (Aug 9, 2012)

Roy Von Rogers said:


> This is what you need, but you may also look for a BRB (big red button) manual disconnect switch instead.
> 
> http://www.ebay.com/itm/Kilovac-EV2...t=BI_Control_Systems_PLCs&hash=item43af8d50ee
> 
> Roy


Thanks Roy, that's more like it!
A little expensive though. Over $200 in Europe.
I want a contactor so I can connect it to the stock fuel pump relay which shuts down in case of a crash.

/ Peter


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## WarpedOne (Jun 26, 2009)

In Europe there is GWL/Power - DC Contactors


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## spoland (Aug 9, 2012)

WarpedOne said:


> In Europe there is GWL/Power - DC Contactors


 Yes, that's the one that weighs over 2kg for a 600A version. I could'nt find any detailed specs for it so I am wondering what would happen if I used the 400A version or even the 200A version (which are both smaller and cheaper).

BTW, I found some specs on a similar or same relay, cant say.
http://www.bcrelays.com/Contactor.HZJ-600A.pdf
It says it is rated for 600A at 27 VDC and the electrical life is 2500 operations.


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## WarpedOne (Jun 26, 2009)

Don't know about those 27VDC, but 2500 cycles are at full 600A load. 
If you don't switch it at full load/current, it will live longer, much longer.


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## Siwastaja (Aug 1, 2012)

27V means 27V... It is probably designed for 12V and 24V battery systems only, so it's useless in an EV.

DC is difficult to break because the arcing does not stop as there is no zero point like in AC. For this reason, the ratings for a DC contactor are _much_ lower than for a physically similar AC contactor.

_Both voltage and current_ ratings are extremely important, as well as the fact that those ratings are for _DC_. Then, in addition, random Chinese products need to be tested in order to verify that the data given is correct.


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## Tesseract (Sep 27, 2008)

spoland said:


> Thanks Roy, that's more like it!
> A little expensive though. Over $200 in Europe.
> I want a contactor so I can connect it to the stock fuel pump relay which shuts down in case of a crash.
> 
> / Peter


Good idea - I like to see an inertia switch (which is often in series with the fuel pump relay) shut down power to the controller and any additional contactors in the battery circuit.

I strongly recommend that any additional contactors installed in the battery circuit either be the Tyco/Kilovac EV200 or the equivalent from GigaVac (which was started by former Kilovac engineers when Kilovac bought out by Tyco, btw). DO NOT USE contactors with low DC voltage ratings (ie - for golf carts, yachts, etc.) or, worse, ones intended for use with AC.

If the cost of the right contactor is a bit too much to swallow over there then a more budget-friendly approach is to put an appropriate DC-rated fuse in series with the positive line inside each battery box (I like Ferraz-Shamut [now Mersen] A50QS series fuses).

Good controller choice, btw...


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## WarpedOne (Jun 26, 2009)

> 27V means 27V... It is probably designed for 12V and 24V battery systems only, so it's useless in an EV.


Thanks for pointing it out. They don't list the voltage at all, just amperage.
So, EV200 it is.


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## Jamie EV (Oct 3, 2012)

Good to know there's an affordable contactor...every other one I've seen is either underrated for voltage, power or both OR is like 300 dollars.


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## Ziggythewiz (May 16, 2010)

~$50 on ebay


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## dtbaker (Jan 5, 2008)

spoland said:


> Thanks Roy, that's more like it!
> A little expensive though. Over $200 in Europe.
> I want a contactor so I can connect it to the stock fuel pump relay which shuts down in case of a crash.
> 
> / Peter



looks like its been cover in later posts, but caught my eye anyway. you're talking about two different things..... main contactor needs to be beefy DC rated job like Kilovac or the big albrights for sure. they are available at the retailers, and pop up on ebay occasionally, but are still not cheap.

the fuel pump interlocks (inertia switch) is a *really good thing* to add to your 12v key-on power to the controller to cut power in case of accident. retail new they are around $50, ebay they pop up all the time around $15 pulled out of junked cars.

reason I am chiming in is that not everybody know that they *should* be installed vertically, with the reset rubber button 'up'. I found that out recently, and still need to re-orient mine in the Swift!

on the same topic of interlocks... comes to mind that the little extra output wire coming out of the Elcon chargers is billed as an interlock to prevent driveaway while plugged in, but it really is not a good one. yes, is cuts voltage to 0 while unit is CHARGING, but it returns pack voltage when the charge cycle in complete, regardless of whether the charger is still plugged in.... in the morning, charge is complete, power is restored , and you can drive away while plugging in even if you use that 'interlock' wire as a KSI power-in to controllers or pot-box.


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