Electric conversion: Project ForkenSwiift - Page 74 - Fuelly Forums

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Old 09-12-2007, 07:15 PM   #731
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will 200 amps do? $16 currently

http://cgi.ebay.com/Cutler-Hammer-2-...QQcmdZViewItem
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Old 09-13-2007, 05:09 AM   #732
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Quote:
Originally Posted by skewbe View Post
Will an AC circuit breaker work for DC? There is 300A worth of service disconnect breakers at my local goodwill for $2 ea. Didn't buy them because I wasn't sure they'd work for DC.
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Old 09-13-2007, 05:18 AM   #733
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I honestly don't know.

I just read this yesterday, but can't comment on it:

Quote:
DC and AC contacting stuff is radically different and shouldn’t be inter-changed!
But then again, wouldn't a knife switch work on either AC or DC? It's just a simple switch. It would seem to me it's all about the current rating, and that's where you need to be careful. You probably can't apply AC ratings to a DC circuit.
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Old 09-13-2007, 05:39 AM   #734
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I don't see a problem using an AC switch in a DC circuit (though not the other way around).

The AC switch has to be over-engineered somewhat because it will see higher voltages. The 110v rating is actually the RMS rating (area under the curve basically), the AC voltage is actually a sinewave that goes all the way up to 170 volts (and higher peak current also).


If you had 110v dc and 110v ac (rms) and hooked them up to a heater coil, they would both produce the same amount of heat.

So, unless we find something that says there is more mojo to it, it *should* work fine.
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Old 09-13-2007, 05:43 AM   #735
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Apparently mr sharkey indicates greater arcing potential in DC (though AC is even better at arcing?!?)
http://www.mrsharkey.com/busbarn/electrics/chapt9.htm

But you are at 48 volts, and this breaker regularly sees 170 volts. And you wanted cheap
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Old 09-13-2007, 08:31 AM   #736
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Quote:
Originally Posted by MetroMPG View Post
I honestly don't know.

I just read this yesterday, but can't comment on it:

But then again, wouldn't a knife switch work on either AC or DC? It's just a simple switch. It would seem to me it's all about the current rating, and that's where you need to be careful. You probably can't apply AC ratings to a DC circuit.
Hmm, I remember from A&P school that DC switches have to have a higher rating than an AC switch because of the arc caused by turning it on or off. AC is able to sustain an arc, but a DC arc does more damage. This is why TIG welders have an high frequency AC 'starter' circuit, then once an arc is established, it switches over to the high-current DC.

I'm looking forward to seeing how you made your terminal ends. I'm getting to the point where I will need some, and I'm planning on using your method.
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Old 09-13-2007, 01:33 PM   #737
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Turns out there's a discussion about this on the EVDL this week. The issue is DC arcing, and one of the old hands says:

Quote:
A AC breaker at the same voltage of the DC source, does not have the larger
contact pads and spacing as a DC breaker. The spacing is contacts spacing
is wider in a DC breaker, so when a DC breaker is activated, there will be
less arc over.
He recommends going 3x over the AC rating for DC use:

Quote:
A circuit
breaker design for 3 hp load on AC is only good for 1 hp on DC. So it about
a 3 to 1 factor.
http://www.nabble.com/Clearing-the-a...html#a12646307

Mouse: I'll post a description of the lug making process soon, and come back and add pics later. I haven't made any new ends since last weekend. This weekend will probably be spent figuring out how to mount contactors etc.

I did sneak out and replace my fried potentiometer today though.
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Old 09-13-2007, 01:44 PM   #738
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While tinkering on the potbox today, I got to thinking about the various sources for recycled parts used in the car so far.
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Old 09-14-2007, 06:49 AM   #739
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Quick cable end-making tutorial for lemmiwinks, Bigmouse... I'll add pics when I make my next batch of ends.
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Old 09-16-2007, 07:04 PM   #740
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Added a few pics to the cable end DIY, above.

Made a few more cables this weekend, and noted that the forklift cables we have used so far are all 3/0, not 4/0 as previously thought. The lugs all say 4/0 on them (the source of my confusion), but the cable itself is 3/0.
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