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Author Topic: Extension cord too long?  (Read 4714 times)

dkw12002

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Extension cord too long?
« on: June 08, 2013, 09:36:01 PM »

I notice both the computer-type cord and my extension cord get fairly warm duing charging. Obviously that accounts for some loss of energy. The extension cord I use is very long but is about the same dia. as the computer cord, so it seems heavy duty enough, but I am wondering if a shorter cord is better than a longer cord as far as not wasting energy? My outlet is about 10 feet from where I park my Zero so the computer cord alone is too short, but I could go to a much shorter extension cord if that would save energy? My question is, does the length of the cord from the charger to the electric outlet have any effect on energy consumption? Thanks.
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Doctorbass

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Re: Extension cord too long?
« Reply #1 on: June 08, 2013, 11:14:59 PM »

What happen is that the volt loss in your extension cord make the cahrger to see less voltage at his input. And it try to compensate by drawing more current. this extra current might raise a little more the temperature of your extension cord ;)

It's normal.. but i would recommand at least having 14 gauge or better like 12 gauge extension to avoid that "problem" ;)

Doc
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protomech

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Re: Extension cord too long?
« Reply #2 on: June 09, 2013, 12:17:57 AM »

The heating of the cord will generally vary with the gauge and conductor material, not the length of the cord. But the voltage drop and the total heating power will be proportional to the length of the cable.

A shorter cable could reduce energy dropped by a bit. I measured the voltage drop at the end of a 50 foot 12 gauge extension cable, it was about 3 volts. So when the charger is pulling about 8 amps then the cable should be heating 24 watts of wasted power. A 10 foot 14 gauge extension cable would waste less power than a 50 foot 12 gauge extension cable.
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Richard230

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Re: Extension cord too long?
« Reply #3 on: June 09, 2013, 03:10:31 AM »

I recently bought a 25-foot long "lightweight" extension cord (which I assume is likely 16 gauge) for stuffing into the frame tube.  Anything heavier and I would not be able to fold the cord up and I wanted the longest cord I could carry on the bike without taking up any space should I ever have a charging emergency and couldn't get too close to the outlet.  I measured 122 volts at the wall and 118 volts at the end of the cord, when connected to my charger.  The cord near the plug got slightly warm, but it was not very obvious.  In any case, the cord was rated for 15 amps, which is a lot higher than the 8 amps that my charger pulls.  Having said that, 14 and 12 gauge extension cords are readily available at any hardware store in 10 or 12 foot lengths for not too much money.  I  believe the cord that you get with your bike from Zero is 14 gauge, at least that is what I got with my 2012 model.

The Zero owner's manual recommends a 12-gauge extension cord not longer than 25-feet for charging my 2012 S.
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dkw12002

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Re: Extension cord too long?
« Reply #4 on: June 09, 2013, 03:26:39 AM »

Thanks for the info, men. Think I'll go find a 12-ga. 10-foot ext. cord.

Update: Bought a 15 ft, 15 amp, 14/3 extension cord to replace my 50 ft. cord of unknown rating. After a half hour of charging the only heat I am feeling is a very small amount right next to the charger and none in the extension cord, so that's a good sign. Before I was feeling more heat in both the computer cord next to the charger and also on the ext. cord side next to both the connection to the computer cord and near the outlet.
« Last Edit: June 09, 2013, 04:35:07 AM by dkw12002 »
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Richard230

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Re: Extension cord too long?
« Reply #5 on: June 09, 2013, 04:34:14 AM »

Thanks for the info, men. Think I'll go find a 12-ga. 10-foot ext. cord.

Look for a "heavy-duty" "contractor's" extension cord.  The ones I have seen are yellow and very stiff.  Expect to pay around $25 at a hardware store, less on-line, no doubt.
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dkw12002

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Re: Extension cord too long?
« Reply #6 on: June 09, 2013, 05:41:06 AM »

The one I got says Contractor Cord. It's called Utilitech Pro. Looks heavy duty.  Thanks, Richard.

Charging for my evening ride. I picked up the bike 8 days ago and have put 800 miles on it. I may use it as my main bike now. I do like to ride and have put 8700 miles on the Gixxer 1000 I bought Jan 26th. I could easily see 10,000 mi. a year on the Zero if I use it as my main bike which seems likely.
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JohnSki

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Re: Extension cord too long?
« Reply #7 on: June 11, 2013, 05:36:57 AM »

People that buy 100 foot 15 amp. extension cords like to put them on a reel to easly wind and unwind them.  If you use a 100 foot 15 amp cord while it is still on the reel it lowers its current capacity to about 7 amps.  This is due to the extension cord now acting like a coil and creating a larger inductive reactance (AC resistance).
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trikester

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Re: Extension cord too long?
« Reply #8 on: June 11, 2013, 09:19:05 AM »

Quote
If you use a 100 foot 15 amp cord while it is still on the reel it lowers its current capacity to about 7 amps.  This is due to the extension cord now acting like a coil and creating a larger inductive reactance (AC resistance).

Not true! I'm speaking of the inductance statement. Because the out and return wires are tightly coupled in the cord most of the inductance is cancelled out, just as in co-ax or twisted pair cables. The small leakage inductance is does have is a very small effect at the low frequency of 60 Hz.

The part of his statement that is correct is the lowering of the rated current if it is coiled on a reel. However, it is not due to inductance it is due to the trapped heat. The wire can't cool well when it is coiled on a reel. This is doubly bad because as the temperature of the wire increases the resistance goes up and the losses get even greater, leading to even more heating. Almost a "run away" situation. :o

Trikester
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dkw12002

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Re: Extension cord too long?
« Reply #9 on: June 11, 2013, 04:06:58 PM »

Electricity has always been enigmatic to me. I remember touring a hydro-electric dam at Ft. Peck, Montana a few years ago and at the end of the tour asking where the lines were taking the electricity out . Turns out, all the electricity generated was going out on 2 small electrical lines, not the huge power lines I would have expected.
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BSDThw

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Re: Extension cord too long?
« Reply #10 on: June 11, 2013, 11:38:10 PM »

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not the huge power lines I would have expected

Did you ask what voltage it was?

Double the voltage and you have half of current, and current is your problem on the line!

Now think why we use 230V  ;)
 
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JohnSki

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Re: Extension cord too long?
« Reply #11 on: June 12, 2013, 05:49:34 AM »

It appears that I was wrong with my above post and Trikester was correct.  I have seen a 100 foot 15 amp extension cord get very hot while coiled on a reel.  I was told by an electrician  that it was because of the inductance and I always assumed that was correct. With a little research I found recommendations of reducing the current capacity by 25 to 50% if coiled but most information refers to not having the cord coiled for a safety issue.
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frodus

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Re: Extension cord too long?
« Reply #12 on: June 12, 2013, 09:41:53 PM »

It's not the inductance as much as it's the resistance of the wire. Every inch of wire has voltage drop. The smaller the wire and higher the amperage draw, the more resitance you get. More resistance, more heat. 100ft cords drawing a full 15A is going to get hot. I've had 10 footers get warm around the receptacle because of high contact resistance.

Keep it short and you'll be good, or use an industrial 15A continuous rated cordset with large conductors. When in doubt, make your own.
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Travis

trikester

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Re: Extension cord too long?
« Reply #13 on: June 12, 2013, 11:08:40 PM »

Quote
It's not the inductance as much as it's the resistance of the wire.

Yes, it has absolutely nothing to do with inductance! It has everything to do with resistance and resistance climbing as the wire gets hotter. If you could put the cord in an ice bath you could run even more current through it (not suggesting that as being practical).

Trikester
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CliC

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Re: Extension cord too long?
« Reply #14 on: June 18, 2013, 04:07:39 AM »

The coiling of the cord also limits its total exposed area and thus its air-cooling ability. Just unwinding the reel will help, too.

But as others have said, shorter/bigger gauge cords are always better (at least until you get to the point where you can't reach the outlet :) )
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