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evnow
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Re: 220V vs. 240V

Sat Jun 19, 2010 9:07 am

http://en.wikipedia.org/wiki/Mains_electricity

Edison selected 100 volts for the lamp as a compromise between distribution costs and lamp costs. Generation was maintained at 110 volts to allow for a voltage drop between generator and lamp.
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Re: 220V vs. 240V

Sat Jun 19, 2010 9:20 am

I am hitting a bunch of conflicting info on the pilot signal meaning. ( I edited my timeout/note above. ) Yes, I've seen the graph that shows 6amp increments (from 6 to 48). But I am certain that older Avcons can provide 32A and rely on the 2001 version of the Standard. It's certainly possible that the 2010 version has changed the meaning of the signal, but unlikely. I don't have access to or am willing to pay for access to the actual standard. If AndyH could help here ... that would be great :)
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Re: 220V vs. 240V

Sat Jun 19, 2010 11:38 am

I received a confirming email reply from a trusted and informed source. As I had suspected The 2010 J1772 Standard is designed around the 80% of breaker ratings for the ranges 30A-80A (meaning 24, 32, 40, 48, 56, 64 amp current draw). The 90A breaker, allowing 72A is reduced to 70A for a special reason encountered with the Tesla: 72A would have required the next larger wire size in the vehicle.

Some info on the 30A/32A confusion: for inexplicable reasons the UL approval for the J1772 connector was done at (and is listed at) 30A, rather than the closest 80% equivalent pilot signal (32A on 40A breaker). At least one EVSE mfg is ignoring the 2A difference.

(Side notes: By implication, the 2001 J1772 Standard is obsolete. A highly rare 35A breaker was ignored in the signaling choices. In the email reply: no mention was made of 100A*80%=80A draw, and signaling below 24A was not addressed (because that's Level 1 ?).)
2011 Silver SL+QC [Mfg: 11/2010] 36mo/15k LEASE
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DeaneG
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Re: 220V vs. 240V

Sat Jun 19, 2010 12:48 pm

Sure would be nice to get specs on the "Nissan" EVSE: is the pilot signal programmable to 24A, or fixed at 32A?
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jkirkebo
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Re: 220V vs. 240V

Sat Jun 19, 2010 12:57 pm

LEAFer wrote:I received a confirming email reply from a trusted and informed source. As I had suspected The 2010 J1772 Standard is designed around the 80% of breaker ratings for the ranges 30A-80A (meaning 24, 32, 40, 48, 56, 64 amp current draw). The 90A breaker, allowing 72A is reduced to 70A for a special reason encountered with the Tesla: 72A would have required the next larger wire size in the vehicle.


Hmm, this all seem somewhat "american" to me. In Europe (at least Scandinavia) we do not have the "80%" rule, we can draw what the breaker allows continously. The most common outlet is 230V 16A which the standard really should accomodate. The next most common one is 230V 10A. Next one after that would be 230V 32A I guess, no problem here. Though it's nearly always 3-phase at >25A but there should be no problem using just one of the phases...?

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DeaneG
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Re: 220V vs. 240V

Sat Jun 19, 2010 1:10 pm

jkirkebo wrote:Hmm, this all seem somewhat "american" to me. In Europe (at least Scandinavia) we do not have the "80%" rule, we can draw what the breaker allows continously.


The 80% rule is indeed american and comes from UL safety standards. Fuses, breakers, etc are sized to barely carry their rated load at 25C, oops, 77 degrees. If they are in a hot environment, they may eventually trip at rated load (you have to scrutinize the manufacturer's data sheet). So as cowboy engineers we derate to 80%.

In the rest of the world, where things seem to be better thought out (CE standards), fuses and breakers are rated to carry 100% of load over their working temperature range.
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Re: 220V vs. 240V

Sat Jun 19, 2010 1:14 pm

DeaneG wrote:Sure would be nice to get specs on the "Nissan" EVSE: is the pilot signal programmable to 24A, or fixed at 32A?

The pilot signal is the EVSE telling the charger on the car what the MAXIMUM available current is. The car can decide to use less (and it should NOT decide to use more!).

Some EVSEs are a] user-programmable to select the maximum current (not necessarily something convenient) and/or b] field technician programmable (rarely adjusted). Much more convenient would be to do the programming on the car's user interface. For example, on a Tesla there's a screen where you can "dial-down" the amount of current to draw from the maximum signaled; and it also has an auto-start-time option for lower night-time rates.

YES! Get us the specs already, Nissan !
2011 Silver SL+QC [Mfg: 11/2010] 36mo/15k LEASE
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DeaneG
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Re: 220V vs. 240V

Sat Jun 19, 2010 1:27 pm

LEAFer wrote:The pilot signal is the EVSE telling the charger on the car what the MAXIMUM available current is. The car can decide to use less (and it should NOT decide to use more!)....YES! Get us the specs already, Nissan !

Right, I was thinking of the people who want to repurpose an existing 240V/30A dryer outlet or circuit. Easy enough if the EVSE can be programmed to signal 24A max.

Or will Nissan mandate a 40A circuit with 32A EVSE signalling in anticipation of a 6.6kW update to the early Leafs?
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AndyH
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Re: 220V vs. 240V

Sat Jun 19, 2010 1:30 pm

I have a copy of the J1772 recommended practice from Jan 2010. I haven't yet played with any hardware designed to use this standard, so cannot say how EVSE manufacturers are actually using the info in the J1772 doc.

According to the document, the Control Pilot signal performs multiple functions. It allows the EVSE to properly detect that a vehicle is connected. The EV receives a signal that the EVSE is ready to supply energy. The EVSE is notified if the charge area needs ventilation. Finally, the EVSE signals the EV, by modulating the pilot duty cycle, to communicate the maximum available continuous current capacity.

5.3.5.1 IF the EV/PHEV reads a duty cycle of 3-7%, the EV/PHEV shall interpret this as a valid digital communications command.

5.3.5.2 IF the EV/PHEV reads a duty cycle between 8% and less than 10%, the EV/PHEV should interpret this as a valid 10% duty cycle.

5.3.5.3 IF the EV reads a duty cycle less than or equal to 85.0% the EV/PHEV should base the current on the Amps = (% duty cycle) * 0.6 formula.

5.3.5.4 If the EV reads a duty cycle greater than 85.0%, the EV/PHEV should base the current on the Amps = (% duty cycle - 64) * 2.5 formula.

5.3.5.5 IF the EV reads a duty cycle of 97%, it is recommended the EV/PHEV consider this as a valid 96% duty cycle.

Image

Image

edit: added duty cycle interpretation table
Last edited by AndyH on Sat Jun 19, 2010 2:49 pm, edited 1 time in total.

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Re: 220V vs. 240V

Sat Jun 19, 2010 1:41 pm

DeaneG wrote:Right, I was thinking of the people who want to repurpose an existing 240V/30A dryer outlet or circuit. Easy enough if the EVSE can be programmed to signal 24A max.

Or will Nissan mandate a 40A circuit with 32A EVSE signalling in anticipation of a 6.6kW update to the early Leafs?


The beauty of adopting a standard is that the vehicle manufacturer doesn't have to waste their time mandating much of anything. ;)

The EVSE can tell the car that anything up to 80A is available, and the car can say "I'm tired today - I only feel like 11.47A. Wake me when we're done."** :D

**Non-technical dramatization - not to be construed as an endorsement of either anthropomorphism or AI in ground vehicles. :lol:

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