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  #11  
Old 07-06-2012, 11:59 PM
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Default Re: [EVDL] paradigm shift

Much like when installing a 30 amp outlet it is required that the circuit
feeding it is sized for 30 amps. Why would an EVSE be any different?
[quote] "Dennis Miles" <xxx@xxx.xxx> wrote:

> I have had the opportunity to review and analyze the circuitry of several
> very popular J1772 EVSE units and although it is provided for in the
> specifications and features as approved by UL, in actual fact, only 50/50
> was implemented in the equipment and instead a specification of source
> power demands sufficient current be available, (economy in Manufacturing by
> simplification of circuitry? Perhaps.) The circuitry
> to ascertain the quantity of current available would seem fairly complex,
> but *printing a specification* stating sufficient current *MUST* be
> supplied is *very inexpensive* !
> Regards,
> *Dennis Lee Miles* (863)944-9913 (call noon to midnight Eastern time)
> *xxx@xxx.xxx*
> *+++++++++++++++++++++++++++++++++++++++++*
> *Offering a 12 day class Sept. 10 to 22, 2012 *
> *in Central Florida. more info on Web;
> WWW.ElectricVehicleTechnicalinstitute.COM<
> http://www.electricvehicletechnicalinstitute.com/>
> *
> *+++++++++++++++++++++++++++++++++++++++++*
> On Fri, Jul 6, 2012 at 1:02 PM, Lee Hart <xxx@xxx.xxx> wrote:
>
> > On 7/6/2012 2:32 AM, Cor van de Water wrote:
> > > If less [power] is available (temporarily) then I might
> > > take action such as dropping a relay to either disable
> > > the charger completely (no AC pass through) or reduce
> > > the charger draw to less than 10A, for example by
> > > simply wiring a resistor in series with the pack on
> > > the output of the charger's transformer and diodes.
> >
> > It's interesting how a constant voltage transformer works. Roughly
> > speaking, it's a standard transformer but wound with a slightly lower
> > primary voltage. Say, a 100vac primary for use on 120vac. The
> > transformer will saturate on the AC line peaks. When it does, the output
> > voltage falls to zero.
> >
> > By itself, this would regulate the output voltage. However, the primary
> > current goes way up when the transformer saturates! So, there is a large
> > extra inductance in series with the primary. When the primary saturates,
> > its voltage falls to to zero, and all the AC input voltage appears
> > across the inductor. This limits the primary current. When the line
> > voltage moves past the peak, the inductor gives up its stored energy.
> > Since it's an inductor, it doesn't lower efficiency like a resistor
> would.
> >
> > But this inductor would give it a poor power factor. So, there is a
> > large AC capacitor across the secondary. It adds capacitive reactance to
> > cancel out the series inductor's inductive reactance, moving the power
> > fact back toward 1.0.
> >
> > The inductor isn't a separate part; they design the transformer to
> > include it. It also has special low-loss core materials because it will
> > operate in saturation. Saturation produces the characteristic "buzz" of
> > a constant-voltage transformer.
> >
> > The simplest way to alter the voltage of a constant voltage transformer
> > is to change the number of secondary turns. This can be done by adding a
> > few turns, which you switch in series (aiding or opposing) to change the
> > voltage. There is almost always room for more turns.
> >
> > The other way is to change the value of the AC capacitor. Less
> > capacitance lowers the output voltage, and more capacitance increases
> > it. This method is only good for perhaps +/-10% because it also affects
> > the power factor and voltage regulation characteristics.
> >
> > The easiest way to adjust the capacitor value is to put a phase
> > controlled light dimmer in series with it. The phase angle adjusts the
> > apparent capacitance, and thus the output voltage. Note that the light
> > dimmer needs to be rated for at least 240vac, because the secondary and
> > capacitor voltage is often 240vac (or more)!
> >
> > Most constant voltage transformer chargers are deliberately designed to
> > have a "taper" charging algorithm. They behave like a "fixed" voltage
> > supply with a series resistance. It delivers maximum current at the
> > lowest pack voltage, and the current falls linearly as the battery
> > voltage rises. But it has two extra useful features; The output is
> > intrinsically current limited (won't deliver more than about 150% into
> > even a shorted battery), and zero-current voltage is only about 120%
> > higher.
> >
> > But when it's desired, they can have a nearly flat voltage vs. current
> > curve. Output voltage can be within +/2% for output currents from 1/4 to
> > full load, and for a +/-20% change in AC line voltage. This makes a good
> > power supply, but a poor lead-acid battery charger. It could be useful
> > for charging lithium batteries, however.
> >
> > --
> > Ring the bells that still can ring
> > Forget your perfect offering
> > There is a crack in everything
> > That's how the light gets in.
> > -- Leonard Cohen, from "Anthem"
> > --
> > Lee A. Hart http://www.sunrise-ev.com/LeesEVs xxx@xxx.xxx
> >
> > _______________________________________________
> > | Moratorium on drag racing discussion is in effect.
> > | Please take those discussions elsewhere. Thanks.
> > |
> > | REPLYING: address your message to xxx@xxx.xxx.edu only.
> > | Multiple-address or CCed messages may be rejected.
> > | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> > | OTHER HELP: http://evdl.org/help/
> > | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
> >
>
>
>
> --
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> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere. Thanks.
> |
> | REPLYING: address your message to xxx@xxx.xxx.edu only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
>
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_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to xxx@xxx.xxx.edu only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
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  #12  
Old 07-07-2012, 08:55 PM
EVDL List EVDL List is offline
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Join Date: Jul 2007
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Default Re: [EVDL] paradigm shift

Roger, Cor. and Peter, the point I was attempting to male was if the 30
amps at 208/240VAC is not available the duty cycle of the 1Khz square wave
is suposed to warn the on vehicle charging equipment, but the major EVSE
J1772 level 2 equipment aren't implementing it in their units, and instead
merely mandating sufficient current be made available. so why implement in
your vehicle if it will likely never actually be called upon to operate???
Regards,
*Dennis Lee Miles* (863)944-9913 (call noon to midnight Eastern time)
*xxx@xxx.xxx*
*+++++++++++++++++++++++++++++++++++++++++*
*Offering a 12 day class Sept. 10 to 22, 2012 *
*in Central Florida. more info on Web;
WWW.ElectricVehicleTechnicalinstitute.COM<http://www.electricvehicletechnicalinstitute.com/>
*
On Sat, Jul 7, 2012 at 1:47 AM, Peter Gabrielsson <
peter.xxx@xxx.xxx> wrote:

> Much like when installing a 30 amp outlet it is required that the circuit
> feeding it is sized for 30 amps. Why would an EVSE be any different?
> [quote] "Dennis Miles" <xxx@xxx.xxx> wrote:
>
> > I have had the opportunity to review and analyze the circuitry of several
> > very popular J1772 EVSE units and although it is provided for in the
> > specifications and features as approved by UL, in actual fact, only 50/50
> > was implemented in the equipment and instead a specification of source
> > power demands sufficient current be available, (economy in Manufacturing
> by
> > simplification of circuitry? Perhaps.) The circuitry
> > to ascertain the quantity of current available would seem fairly complex,
> > but *printing a specification* stating sufficient current *MUST* be
> > supplied is *very inexpensive* !
> > Regards,
> > *Dennis Lee Miles* (863)944-9913 (call noon to midnight Eastern time)
> > *xxx@xxx.xxx*
> > *+++++++++++++++++++++++++++++++++++++++++*
> > *Offering a 12 day class Sept. 10 to 22, 2012 *
> > *in Central Florida. more info on Web;
> > WWW.ElectricVehicleTechnicalinstitute.COM<
> > http://www.electricvehicletechnicalinstitute.com/>
> > *
> > *+++++++++++++++++++++++++++++++++++++++++*
> > On Fri, Jul 6, 2012 at 1:02 PM, Lee Hart <xxx@xxx.xxx> wrote:
> >
> > > On 7/6/2012 2:32 AM, Cor van de Water wrote:
> > > > If less [power] is available (temporarily) then I might
> > > > take action such as dropping a relay to either disable
> > > > the charger completely (no AC pass through) or reduce
> > > > the charger draw to less than 10A, for example by
> > > > simply wiring a resistor in series with the pack on
> > > > the output of the charger's transformer and diodes.
> > >
> > > It's interesting how a constant voltage transformer works. Roughly
> > > speaking, it's a standard transformer but wound with a slightly lower
> > > primary voltage. Say, a 100vac primary for use on 120vac. The
> > > transformer will saturate on the AC line peaks. When it does, the
> output
> > > voltage falls to zero.
> > >
> > > By itself, this would regulate the output voltage. However, the primary
> > > current goes way up when the transformer saturates! So, there is a
> large
> > > extra inductance in series with the primary. When the primary
> saturates,
> > > its voltage falls to to zero, and all the AC input voltage appears
> > > across the inductor. This limits the primary current. When the line
> > > voltage moves past the peak, the inductor gives up its stored energy.
> > > Since it's an inductor, it doesn't lower efficiency like a resistor
> > would.
> > >
> > > But this inductor would give it a poor power factor. So, there is a
> > > large AC capacitor across the secondary. It adds capacitive reactance
> to
> > > cancel out the series inductor's inductive reactance, moving the power
> > > fact back toward 1.0.
> > >
> > > The inductor isn't a separate part; they design the transformer to
> > > include it. It also has special low-loss core materials because it will
> > > operate in saturation. Saturation produces the characteristic "buzz" of
> > > a constant-voltage transformer.
> > >
> > > The simplest way to alter the voltage of a constant voltage transformer
> > > is to change the number of secondary turns. This can be done by adding
> a
> > > few turns, which you switch in series (aiding or opposing) to change
> the
> > > voltage. There is almost always room for more turns.
> > >
> > > The other way is to change the value of the AC capacitor. Less
> > > capacitance lowers the output voltage, and more capacitance increases
> > > it. This method is only good for perhaps +/-10% because it also affects
> > > the power factor and voltage regulation characteristics.
> > >
> > > The easiest way to adjust the capacitor value is to put a phase
> > > controlled light dimmer in series with it. The phase angle adjusts the
> > > apparent capacitance, and thus the output voltage. Note that the light
> > > dimmer needs to be rated for at least 240vac, because the secondary and
> > > capacitor voltage is often 240vac (or more)!
> > >
> > > Most constant voltage transformer chargers are deliberately designed to
> > > have a "taper" charging algorithm. They behave like a "fixed" voltage
> > > supply with a series resistance. It delivers maximum current at the
> > > lowest pack voltage, and the current falls linearly as the battery
> > > voltage rises. But it has two extra useful features; The output is
> > > intrinsically current limited (won't deliver more than about 150% into
> > > even a shorted battery), and zero-current voltage is only about 120%
> > > higher.
> > >
> > > But when it's desired, they can have a nearly flat voltage vs. current
> > > curve. Output voltage can be within +/2% for output currents from 1/4
> to
> > > full load, and for a +/-20% change in AC line voltage. This makes a
> good
> > > power supply, but a poor lead-acid battery charger. It could be useful
> > > for charging lithium batteries, however.
> > >
> > > --
> > > Ring the bells that still can ring
> > > Forget your perfect offering
> > > There is a crack in everything
> > > That's how the light gets in.
> > > -- Leonard Cohen, from "Anthem"
> > > --
> > > Lee A. Hart http://www.sunrise-ev.com/LeesEVs xxx@xxx.xxx
> > >
> > > _______________________________________________
> > > | Moratorium on drag racing discussion is in effect.
> > > | Please take those discussions elsewhere. Thanks.
> > > |
> > > | REPLYING: address your message to xxx@xxx.xxx.edu only.
> > > | Multiple-address or CCed messages may be rejected.
> > > | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> > > | OTHER HELP: http://evdl.org/help/
> > > | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
> > >
> >
> >
> >
> > --
> > -------------- next part --------------
> > An HTML attachment was scrubbed...
> > URL:
> >
> http://lists.sjsu.edu/mailman/private/ev/attachments/20120707/e127d71d/attachment.html
> > _______________________________________________
> > | Moratorium on drag racing discussion is in effect.
> > | Please take those discussions elsewhere. Thanks.
> > |
> > | REPLYING: address your message to xxx@xxx.xxx.edu only.
> > | Multiple-address or CCed messages may be rejected.
> > | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> > | OTHER HELP: http://evdl.org/help/
> > | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
> >
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL:
> http://lists.sjsu.edu/mailman/private/ev/attachments/20120706/03ce6e96/attachment.html
> _______________________________________________
> | Moratorium on drag racing discussion is in effect.
> | Please take those discussions elsewhere. Thanks.
> |
> | REPLYING: address your message to xxx@xxx.xxx.edu only.
> | Multiple-address or CCed messages may be rejected.
> | UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
> | OTHER HELP: http://evdl.org/help/
> | CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
>



--
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_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to xxx@xxx.xxx.edu only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
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  #13  
Old 07-07-2012, 10:45 PM
EVDL List EVDL List is offline
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Default Re: [EVDL] paradigm shift

[quote]On 7 Jul 2012 at 22:51, Dennis Miles wrote:

> so why implement in your vehicle if it will likely never actually be
> called upon to operate?

I'm not an expert on these matters,and it's quite possible that I've missed
something here. But the cussedness of things is such that if it's in the
specification, someday someone is going to use it.

If you're a hobbyist doing a conversion, this might not matter. You just
implement it when you actually need it, or you don't use some charging
station.

But if you're building EVs for sale, you disregard such matters at your
peril. Dealing with customer complaints can be hazardous to your bottom
line.

But as I say, perhaps I'm missing something here.

David Roden - Akron, Ohio, USA
EVDL Administrator

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_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to xxx@xxx.xxx.edu only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
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  #14  
Old 07-08-2012, 07:45 AM
EVDL List EVDL List is offline
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Default Re: [EVDL] paradigm shift

Because although most EVSE's use a fixed 30A supply, you may want to
charge at a low-power EVSE that uses a fixed 12A or 16A.
Alternatively, you may want to charge somewhere where the local
electric utility is doing a project with EVSE makers and businesses to
adjust available current based on grid loading.

-Morgan LaMoore

[quote] Dennis Miles <xxx@xxx.xxx> wrote:
> Roger, Cor. and Peter, the point I was attempting to male was if the 30
> amps at 208/240VAC is not available the duty cycle of the 1Khz square wave
> is suposed to warn the on vehicle charging equipment, but the major EVSE
> J1772 level 2 equipment aren't implementing it in their units, and instead
> merely mandating sufficient current be made available. so why implement in
> your vehicle if it will likely never actually be called upon to operate???
> Regards,
> *Dennis Lee Miles* (863)944-9913 (call noon to midnight Eastern time)
> *xxx@xxx.xxx*

_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to xxx@xxx.xxx.edu only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
| OTHER HELP: http://evdl.org/help/
| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
Reply With Quote
  #15  
Old 07-08-2012, 12:35 PM
EVDL List EVDL List is offline
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Join Date: Jul 2007
Posts: 70
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Default Re: [EVDL] paradigm shift

[quote]Dennis Miles wrote:

> Roger, Cor. and Peter, the point I was attempting to male was if the 30
> amps at 208/240VAC is not available the duty cycle of the 1Khz square wave
> is suposed to warn the on vehicle charging equipment, but the major EVSE
> J1772 level 2 equipment aren't implementing it in their units, and instead
> merely mandating sufficient current be made available. so why implement in
> your vehicle if it will likely never actually be called upon to operate???

The function of the pilot signal is not to warn that 30A is unavailable, but rather to inform the charger how much AC current (6-80A) it is *allowed* to use at this particular time.

The reason to implement it on your vehicle is that it is already in use to inform the charger of the capabilities of the particular EVSE (e.g. some EVSEs available for private purchase are only capable of 3.6kW (15A@240V) or 7.2kW, and the opportunity charge cords provided with OEM vehicles use the pilot signal to inform the charger not to draw more than 1.6kW), and it is likely that future EVSEs will include the ability to vary the pilot signal to regulate the load.

My point is not that everyone should rush out to implement the full pilot signal functionality in their vehicle (though you might well consider that the chargers in OEM EVs do...), but rather that merely slapping a J1772 inlet on your vehicle and spoofing the pilot signal handshake to turn on the AC power does not constitute having implemented J1772, and does not ensure that you can plug in and charge from any J1772 EVSE.

It is certainly a valid point that if your charger is reasonably small (e.g. 3.3kW or less), then it is unlikely that you will get into trouble without full pilot signal functionality, at least at the present time.

Cheers,

Roger.


_______________________________________________
| Moratorium on drag racing discussion is in effect.
| Please take those discussions elsewhere. Thanks.
|
| REPLYING: address your message to xxx@xxx.xxx.edu only.
| Multiple-address or CCed messages may be rejected.
| UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub
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| CONFIGURE: http://lists.sjsu.edu/mailman/listinfo/ev
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