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LEAFer
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Re: 220V vs. 240V

Sat Jun 19, 2010 2:00 pm

Thanks, Andy. Very helpful.

So ... the signaling is less "discrete" (not "discreet" :lol: ) than I thought. But because of the "2% accuracy" it's also APPARENTLY not completely continuous. It looks like 6A is possible and many values in-between all the way up to 80A. Interestingly, 32A is not really possible, but 30A is (50% duty cycle), unless the EVSE gives an exact (32/0.6=) 53.33% duty cycle and the car accurately interprets this (without rounding) to mean 32A can be drawn.

I stand corrected on some of my above discrete "pilot signal" speculation, and still looking for Nissan's spec "or someone like him" !
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Rat
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Re: 220V vs. 240V

Sat Jun 19, 2010 2:04 pm

Wow! Lots of good info here, but I'm still not sure what I'm going to get hit for by the electrician. With the assessment only 3 weeks away, I guess I'll find out soon enough. I have a 200A Sylvania panel put in when we remodeled in the mid 1980s. The garage "220V" line breaker is 30A. I don't know what gauge wire is used, but at least conduit is already run to the garage. Is it likely the previous contractor used a gauge wire that can take 40A even though the breaker was 30A? Thinking about it now, I doubt that, since that contractor probably never touched that particular circuit as it was unused, unless he had to rewire it due to the breaker panel being moved a greater distance from the garage. Even then, maybe he just spliced in more wire, with the original wire staying as part of it. The original wire put in during the 1950s when the house was built is probably still there. I assume the electrician can use the same conduit (pulling out the old wire if necessary, since it is not used for the gas dryer we have), but I'm not sure whether that is harder than running another one through the attic. I think there's room on the panel for another circuit.
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AndyH
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Re: 220V vs. 240V

Sat Jun 19, 2010 2:47 pm

LEAFer wrote:Thanks, Andy. Very helpful.

So ... the signaling is less "discrete" (not "discreet" :lol: ) than I thought. But because of the "2% accuracy" it's also APPARENTLY not completely continuous. It looks like 6A is possible and many values in-between all the way up to 80A. Interestingly, 32A is not really possible, but 30A is (50% duty cycle), unless the EVSE gives an exact (32/0.6=) 53.33% duty cycle and the car accurately interprets this (without rounding) to mean 32A can be drawn.

I stand corrected on some of my above discrete "pilot signal" speculation, and still looking for Nissan's spec "or someone like him" !


Glad to help!

I added the EVSE signaling and EV interpretation table to my post to keep it together. I think that'll help with the 2%.

The impression I get from the doc is that the installer/electrician must do the math to properly set the max power the EVSE draws from the supply side. While the J1772 document's examples show fixed value resistors for this setting, I expect either a variable resistor or a microprocessor controlled setting within the EVSE. The installer may absolutely be able to set the EVSE for a 32A max.

For the pilot signal and response from the EV, it appears to be capable of continuously variable analog adjustment between 8A and 80A. The EVSE is supposed to signal within it's ±2% overall tolerance, but there's no indication that the EV is supposed to filter the control signal within the 8 and 80A 'working zone.'

Andy

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planet4ever
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Re: 220V vs. 240V

Sat Jun 19, 2010 3:26 pm

I'll bet Rat had no idea how technical this thread was going to get when he asked his innocent question, "What's the difference between 220V and 240V?" Great stuff, guys. Thanks for all the digging.
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mitch672
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Re: 220V vs. 240V

Sat Jun 19, 2010 6:47 pm

Rat wrote:Wow! Lots of good info here, but I'm still not sure what I'm going to get hit for by the electrician. With the assessment only 3 weeks away, I guess I'll find out soon enough. I have a 200A Sylvania panel put in when we remodeled in the mid 1980s. The garage "220V" line breaker is 30A. I don't know what gauge wire is used, but at least conduit is already run to the garage. Is it likely the previous contractor used a gauge wire that can take 40A even though the breaker was 30A? Thinking about it now, I doubt that, since that contractor probably never touched that particular circuit as it was unused, unless he had to rewire it due to the breaker panel being moved a greater distance from the garage. Even then, maybe he just spliced in more wire, with the original wire staying as part of it. The original wire put in during the 1950s when the house was built is probably still there. I assume the electrician can use the same conduit (pulling out the old wire if necessary, since it is not used for the gas dryer we have), but I'm not sure whether that is harder than running another one through the attic. I think there's room on the panel for another circuit.


for a 30A circuit, the standard wire used would be "10 gauge". Don't assume the conduit will be reused, most won't be, because it may be undersized for the current "National Electric Code", since it was originaly sized for a 1950's NEC.

You can pretty much assume he's going to want to run his own conduit, and wire, and supply a circuit breaker for your panel. He has to warrant his work, he can't do that with existing wire/conduit.
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