You wouldn't even need a central instruction.  It could be the same V2G
electronics, but only one way.  That is, when there's a dip in voltage
charging decreases.  The bigger the dip, the more the charge shuts down.

I suppose it could also react to spikes and absorb extra current for a
moment, too.

But it wouldn't put anything back into the grid.


-----Original Message-----
From: EV [] On Behalf Of Bill Dube via EV
Sent: 06 June, 2014 12:27 PM
To: Cor van de Water; Electric Vehicle Discussion List
Subject: Re: [EVDL] V2G at L1 is practical

If you are concerned about your EV somehow supplying unwanted 
current, burning up wires, juicing an electrician, etc. one could 
think of several ways to electronically sense if the grid had gone 
dark, or some circuit breaker in the chain had tripped.

I agree that if the GFCI didn't trip when drawing current (like when 
normally charging,) then it certainly won't trip when supplying 
current. Not an issue.

A lone 20 amp 120 volt circuit doesn't matter for frequency 
stabilization, but large numbers of 20 amp 120 volt circuits would. 
If V2G were a standard feature in EVs, and a large number of EVs were 
plugged in, then it would make a big difference. However, simply 
listening for a central instruction from the local utility to "pause 
charging" for a few minutes would be _much_ cheaper to implement and 
would be nearly as effective.

The local utility issues such signals to "saver switch" type devices 
here in Colorado:

You can put your EV charger on a "saver switch" that is controlled by 
the utility. Simple.

Bill Dube'

At 12:32 PM 6/6/2014, you wrote:
>GFCI has no influence on backfeeding, except when a ground fault
>triggers it and it disconnects.
>I agree that L1 power is sufficient for charging EVs most of the time
>(I am 99.9% L1 charge user)
>My only concern is if the grid support can be delivered through L1,
>in other words - can an EV give a meaningful support to the grid if it
>is limited to 1.5kW?
>The other concern is that most L1 outlets are shared (I mean: more
>outlets on the same circuit breaker) whereas a backfeeding generator
>preferably is on its own breaker to avoid that you can draw power power
>from the *other* outlets than that the breaker is protecting - there is
>a small risk of burning up the wires without the breaker triggering if
>the backfeeder if giving a steady stream of power (most notably this
>occurs with solar, that is why an inverter is typically always on a
>separate circuit with no other loads connected to the same circuit).
>Since I have no clue about the typical power levels involved with grid
>stabilization, I leave my first concern unanswered - hopefully someone
>else can contrtribute meaningfully to that one.
>Cor van de Water
>Chief Scientist
>Proxim Wireless Corporation
>Email: Private:
>Skype: cor_van_de_water Tel: +1 408 383 7626

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