# U.S. source for 250 amp disconnect?



## JRP3 (Mar 7, 2008)

I like this Nanfeng emergency disconnect button but I'd rather not pay shipping from Aus http://www.evworks.com.au/index.php?product=SWI-ZJK250









I've seen similar here but for almost 3 times the price.
http://www.tecknowledgey.com/catalo...=1513&osCsid=7b3b4947060881387755e220102cf404


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## david85 (Nov 12, 2007)

No kidding. I can't seem to find anything suitable either. Currently I have no safety disconnect in my car at all.

The prices of this stuff is what really gets me. Its practically ww2 technology, why the heck is it so expensive?

Even the contacters that you get from EV suppliers often have to be paralleled to get the amp rating high enough.


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## EV-propulsion.com (Jun 1, 2009)

not only the current rating, but just as important watch the voltage rating- the higher the voltage, the more possibility of jumping the air gap-especially with our DC equipment. If you are going to depend on a low voltage rated emergency stop it may not work as you hope..and yes, the pickings are very slim in this area, we haven't found any _mechanical _switch suitable for high voltage EVs
Maybe somebody has to make an IGBT disconnect switch or some other electronic switching........
Mike
www.EV-propulsion.com


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## JRP3 (Mar 7, 2008)

Maybe some EV importer can get a bunch of these shipped over here. Rod Dilkes from evworks said he's tested these switches at 300V. If he can sell them for $29 a bulk order would probably be much less than that. You could sell them here for $50 or so.


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## JRP3 (Mar 7, 2008)

David, aren't you going to Aus soon? You could bring a few back with you.


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## EV-propulsion.com (Jun 1, 2009)

yes, but did he test them on a 300 volt system and try to break a 500+ amp load at 300 volts ? There is a big difference between a service switch and a emergency,full load disconnect. It seems like from the start of this thread that these switches would be used as an emergency disconnect- although they may work well as a disconnect for parking. You can many times get away with using a lower voltage rated switch at a higher voltage, just don't make or break the circuit with a load on it (like an emergency). Ratings are supposed to be what amperage they can make or break and at what voltage safely.
I personally wouldn't sell it as an emergency disconnect switch without testing it fully under high voltage high load. It would probably be fine for disconnecting circuits while servicing, etc.....and it may work once in an emergency without melting together...or maybe not....
Mike
www.EV-propulsion.com


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## Dave Koller (Nov 15, 2008)

Just curious - has anyone looked at these close up? what are the contacts made of? Doesn't look like much to machine or make..


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## david85 (Nov 12, 2007)

I suspect we may have to look off shore to find what we need here. I heard of some one in Australia that bought a small volume of high voltage relays from Ebay. He only needed one, but others asked for a few so he got extras. Not sure if thats who you're talking about, JP.

There are some nice looking products on alibaba from asia (china, hong king mainly), but again, its a crap shoot to figure out which ones will work and which ones won't.


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## JRP3 (Mar 7, 2008)

david85 said:


> I suspect we may have to look off shore to find what we need here. I heard of some one in Australia that bought a small volume of high voltage relays from Ebay. He only needed one, but others asked for a few so he got extras. Not sure if thats who you're talking about, JP.
> 
> There are some nice looking products on alibaba from asia (china, hong king mainly), but again, its a crap shoot to figure out which ones will work and which ones won't.


I was talking about the Nanfeng disconnect switch pictured in the first post. Rod Dilkes sells them at evworks.com in Australia for $29, I'm just afraid shipping from there would be almost as much. It would still be cheaper than anything else I've found here. Exchange rate might be in my favor.


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## JRP3 (Mar 7, 2008)

EV-propulsion.com said:


> yes, but did he test them on a 300 volt system and try to break a 500+ amp load at 300 volts ?


That I'm not sure of. I'd only be using it on a 120 volt system.


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## david85 (Nov 12, 2007)

JRP3 said:


> I was talking about the Nanfeng disconnect switch pictured in the first post. Rod Dilkes sells them at evworks.com in Australia for $29, I'm just afraid shipping from there would be almost as much. It would still be cheaper than anything else I've found here. Exchange rate might be in my favor.


That is cheap.....

Maybe you can ask about sea mail. Would probably take about 3-4 weeks to get to you, but I've found that a month isn't really that long with an EV build

Exchange rate is only about 8% last I checked. It will add up but not by too much.

EDIT: and his prices seem to include GST. You are outside Au so in theory you would be getting a break there too.


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## Tesseract (Sep 27, 2008)

Even at 120VDC you need to use magnetic blowouts and/or arc chutes, interrupters, etc., plus solid copper or copper/molybdenum contacts, to be able to break more than a few dozen amps. 

That Nanfeng - or whatever it's called - looks like it'll make a great arc lamp if used to interrupt an actual short circuit in the typical EV.


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## JRP3 (Mar 7, 2008)

Tesseract said:


> That Nanfeng - or whatever it's called - looks like it'll make a great arc lamp if used to interrupt an actual short circuit in the typical EV.


Buzz kill  Once again you foil my attempts to be a cheap ass  The Albright I linked to can be had with blowouts, (for an extra $3.50), and can break 1000 amps at 96 volts. http://www.tecknowledgey.com/catalog/pdf/disconnects.pdf


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## Dave Koller (Nov 15, 2008)

JRP3 said:


> Buzz kill  Once again you foil my attempts to be a cheap ass  The Albright I linked to can be had with blowouts, (for an extra $3.50), and can break 1000 amps at 96 volts. http://www.tecknowledgey.com/catalog/pdf/disconnects.pdf


And ya gotta love the key one  .. crash crash tinkle -- err wheres my key... /


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## JRP3 (Mar 7, 2008)

The keyed unit only uses a key for turn on, not turn off


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## david85 (Nov 12, 2007)

JRP3 said:


> The keyed unit only uses a key for turn on, not turn off


Yes, but thats not so funny to visualize

Almost as good as having to inflate your own air bag before a crash.


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## Dave Koller (Nov 15, 2008)

So David are you going to bring a suitcase full of them back thru customs ?


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## david85 (Nov 12, 2007)

Dave Koller said:


> So David are you going to bring a suitcase full of them back thru customs ?


Not likely, they're in western austrailia. I'll be north of brisbane which is the other end of the continent. Driving across the outback is not recommended. However an order big enough could probably be done by sea, and maybe get a break off the price anyway. Some asian companies are starting to offer free shipping worldwide and thats how they do it. Sea shipping instead of expensive air mail.


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