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DeaneG
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Re: EVSE Home Assessment Reports

Sat Jul 03, 2010 6:53 pm

LEAFer wrote:It's an "inductor" issue. You're creating an inductance and heat associated therewith. When tightly coiled and improperly stored while carrying a large current a heat build up could cause a fire.
Sorry, not correct. If anything it would be a resistive heating issue, but very unlikely.
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evnow
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Re: EVSE Home Assessment Reports

Sat Jul 03, 2010 6:57 pm

LEAFer wrote:It's an "inductor" issue. You're creating an inductance and heat associated therewith. When tightly coiled and improperly stored while carrying a large current a heat build up could cause a fire.
Hmmm ... no. Only noticeable heating that happens here would be because of resistance. Eddy currents, if any, would be too small.
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Re: EVSE Home Assessment Reports

Sat Jul 03, 2010 7:25 pm

mitch672 wrote:
LEAFer wrote:
mwalsh wrote:TOU-D-TEV is whole house tiered, but with EV charging on a specific super off-peak schedule and rate.
On that rate, without the benefit of a second meter (like TOU-EV-1) how do they know what usage to assign to the car, as opposed to something else (hot tub, laundry, my new jiga-watt time-machine, ...) ?
probably by looking at the same load nearly every night, during off peak hours, then assuming that would be the EV charging.. of course the usage will be different based on the miles driven each day, but most likely it will fall into some type of repeatable pattern (or nearly so)
I don't think that is how they will no. As of now my power company has smart meters and communicate daily on how much I use. Maybe the car will communicate with the power company as it communicate with the
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Re: EVSE Home Assessment Reports

Sat Jul 03, 2010 7:29 pm

evnow wrote:
LEAFer wrote:It's an "inductor" issue. You're creating an inductance and heat associated therewith. When tightly coiled and improperly stored while carrying a large current a heat build up could cause a fire.
Hmmm ... no. Only noticeable heating that happens here would be because of resistance. Eddy currents, if any, would be too small.
Well, inductance is a type of resistance (magnetic field). You are concentrating the fields in a tight coil and creating self-inductance with losses (creating heat) proportional to the number of loops and inversely proportional to the diameter of the coil. I don't have a PhD in this, and so my explanation may be slightly off. But the bottom line is ... a fire can result. See HERE for just one example (googling will find many more).
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Re: EVSE Home Assessment Reports

Sun Jul 04, 2010 7:39 am

The inductor is a coil of wire that carries "net" current flowing in the coil. Here, the Out and In power currents in the cord essentially cancel each other out, so there is no "net" current flowing. So no magnetic field, and no inductance. Same thing for a coiled 100' extension cord. No inductance problem.

But, all the cord might be "required" to be off the hook when charging, for their "strain-relief" to work.

If this is true, how can they recommend "using" the cord "overhead" to keep it off the floor (to avoid tripping over it)?

Coiling during non-use really SHOULD not be a problem. If they say it is, ask for a written description of their unit's "limitation".
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garygid
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Re: EVSE Home Assessment Reports

Sun Jul 04, 2010 1:08 pm

On the no-cost e-fuel cord length option, please ask if the cord "disconnects" relatively easily at the EVSE end, so one could use the shorter 15' length for most in-garage charging, but occasionally use the 25' cord to charge in the driveway.

If the cord is (or can be) user-swapped, then please ask for the price of a replacement (or extra) 15' cord (and for a 25' cord).

Thanks.
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Re: EVSE Home Assessment Reports

Sun Jul 04, 2010 1:09 pm

Good idea Gary!
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garygid
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Re: EVSE Home Assessment Reports

Sun Jul 04, 2010 1:15 pm

Has anybody been told that they need a (possibly fused) disconnect within "line of sight" of the EVSE?

Is the "fused" part necessary, if it comes from a breaker?

If fused, what type and rating of fuse to go with a 40-amp breaker?
Perhaps 40 Amps?

Thanks
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garygid
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Re: EVSE Home Assessment Reports

Sun Jul 04, 2010 1:21 pm

Normally, wiring from a 40-amp breaker would be #8, or possibly high-temperature (90ºC insulation) #10 wire, right?

What are you being told for in-conduit wires (of what length)?
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EVDRIVER
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Re: EVSE Home Assessment Reports

Sun Jul 04, 2010 2:14 pm

LEAFer wrote:
evnow wrote:
LEAFer wrote:It's an "inductor" issue. You're creating an inductance and heat associated therewith. When tightly coiled and improperly stored while carrying a large current a heat build up could cause a fire.
Hmmm ... no. Only noticeable heating that happens here would be because of resistance. Eddy currents, if any, would be too small.
Well, inductance is a type of resistance (magnetic field). You are concentrating the fields in a tight coil and creating self-inductance with losses (creating heat) proportional to the number of loops and inversely proportional to the diameter of the coil. I don't have a PhD in this, and so my explanation may be slightly off. But the bottom line is ... a fire can result. See HERE for just one example (googling will find many more).

Sure, over load an improper sized cord and it will get very hot, coil the very hot cord and it creates more heat. The idea of the EVSE cord doing this is silly as it will be rated properly and highly insulated.

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