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Re: EVSE source current

Posted: Tue Jul 13, 2010 10:52 am
by LTLFTcomposite
LEAFer wrote:
LTLFTcomposite wrote:not to mention if you have a dedicated 120v 20A receptacle you could convert it to 240V just by changing to a double pole breaker
Yes, but I wouldn't want to do that with a 120V NEMA 5-15/20 receptacle ... it WILL cause accidents. So, converting to the NEMA 6 series (which is 240volts) will prevent that. But, of course, in addition you would do as you said, "convert" the 20A dedicated (only one outlet) circuit from a single to double-pole breaker (and watch the wiring hot-hot-ground when you replace the plug at the end of the EVSE).

Any expert here ... agree this would work ?

(Edit: to keep the EVSE unmodified, could make an adapter (or pigtail) instead (from NEMA 5-15R to NEMA 6-20P.)
Obviously you'd change the receptacle device. Don't forget to wrap some black tape around the white (previously neutral) wire at both ends :-)

The pigtail is a good idea. That way when you call the dealer to have it towed in for repairs you can just stand there with your hands in your pockets and say "I don't know what happened, it just started smoking!"

Re: EVSE source current

Posted: Tue Jul 13, 2010 11:23 am
by LEAFer
LTLFTcomposite wrote:... just stand there with your hands in your pockets and say "I don't know what happened, it just started smoking!"
... :lol:

Re: EVSE source current

Posted: Tue Jul 13, 2010 11:31 am
by johnr
LTLFTcomposite wrote:Here's something to think about... the 120 volt cord plugs into the 1772 connector right? Is there a counterpart to that for cars being sold in Europe where 220 is the norm? I wonder if the on board charger is voltage sensing.. ie same thing for both Europe and US.
Wow, I didn't think about that! Most power adapters are of the switching type and can accept anywhere from 100-240V so just by changing the plug connector you can use them anywhere in US or Europe. Of course the portable 120V emergency EVSE is not exactly a switching power adapter (it's mostly an extension cord with a safety box), but I wonder if the same principle holds true here. Maybe Nissan has designed the emergency EVSE to be multi-voltage capable (this cuts costs as they wouldn't have to make both versions) and the only change they make is putting a different plug on the end? Now if that is the case, maybe converting the 120V emergency EVSE to be able to use on a 240V outlet for faster charging would only require plugging it in to an adapter plug. Or not. Or maybe?

Re: EVSE source current

Posted: Tue Jul 13, 2010 11:55 am
by EVDRIVER
johnr wrote:
LTLFTcomposite wrote:Here's something to think about... the 120 volt cord plugs into the 1772 connector right? Is there a counterpart to that for cars being sold in Europe where 220 is the norm? I wonder if the on board charger is voltage sensing.. ie same thing for both Europe and US.
Wow, I didn't think about that! Most power adapters are of the switching type and can accept anywhere from 100-240V so just by changing the plug connector you can use them anywhere in US or Europe. Of course the portable 120V emergency EVSE is not exactly a switching power adapter (it's mostly an extension cord with a safety box), but I wonder if the same principle holds true here. Maybe Nissan has designed the emergency EVSE to be multi-voltage capable (this cuts costs as they wouldn't have to make both versions) and the only change they make is putting a different plug on the end? Now if that is the case, maybe converting the 120V emergency EVSE to be able to use on a 240V outlet for faster charging would only require plugging it in to an adapter plug. Or not. Or maybe?

Perhaps, the current rating could remain the same with the kw doubling.

Re: EVSE source current

Posted: Tue Jul 13, 2010 12:22 pm
by garygid
Max Current:
At (almost) best, the "Max Current" (12, 15, 16, 20, 24, 30, 32, 40, 50-amp) setting in the EVSE is a "jumper" on a printed circuit board.

Middle ground of difficulty is a component change, or two (R or C).

Most difficult is a built-in firmware fuse-ROM setting (that would be difficult to find, and could be very difficult to change.

Voltage Change:
Most of the EVSE components are likely to work at 120v and 240 volts, even if something like the relay is only "rated" for 120v.

The exception could easily be input rating on the internal low-voltage power supply.

The GFI is probably one that measures the "net" current going through the pair of "hot" wires to the car. The current "sum" should be very near zero. Usually detection of 4 or 5 milli-amps is enough to trip the GFI. In this application, they might use something more like 20 ma as the "trip" current.

Re: EVSE source current

Posted: Tue Jul 13, 2010 12:22 pm
by LEAFer
EVDRIVER wrote:Perhaps, the current rating could remain the same with the kw doubling.
Right! That's what I was hoping for. And like I posted above, even at the EVSE's forced limit of 12A, doubling to 240V, gets us very close to the initial car's charger limit of 3.3kW. (12A * 240V = 2.88kW). So that reduces a full 24kWh charge to 8.3 hrs (plus; due to losses and slow down near end).

And in most cases you're not near empty ... so ... even if you come home late, you should be "full" by morning. 8-)

Re: EVSE source current

Posted: Tue Jul 13, 2010 1:19 pm
by AndyH
Too many guess without facts, gents! Take another look at the j1772 spec - specifically pages 11 and 12. The image has been posted on the forum as well.

The EVSE can be roughly thought of as an extension cord that connects the charger to the AC source - 120V or 240V. Yes - the extension cord has a disconnect device - like a relay or contactor - but it doesn't modify the input power in any way from the wall to the charger.

The EVSE has a separate 'black box' of control electronics that produces the pilot signal and monitors the disconnect switchs on the both the charge coupler and the car.

If the car's computers detect an out of spec condition, it opens its switch and charging stops. If someone presses the 'release' button on the J1772 handle, that switch opens and charging stops. If the EVSE detects trouble with the source or a ground fault then it will stop feeding power to the car.

We know that the J1772 standard allows both 120V and 240V charging. We know that the J1772 device uses the same wires and terminals to send 120V and 240V to the charger. We know that the J1772 EVSE does not report any voltage info to the car. This means to me that the car's charge system MUST detect and adjust to incoming line voltage on its own without input from the EVSE. This suggests to me that we can ignore input voltage and frequency.

The difference between US L1 15A, US L1 20A, UK L1, Japanese L1, or US L2 with regard to the pilot signal is only the current limit encoded into the pilot signal. (Yes - there's wiring, max design current for the specific device, agency approvals, etc. as well.)

I expect that it'll be less expensive to put a dryer cord on our AV L2 EVSE than buy a device from another company or import one from Europe or the Far East. The quotes I'm getting for L1 and L2 EVSE are more than twice what AV is getting for their L2 device - unless we can find something less expensive, AV is still the way to go.

Andy

Re: EVSE source current

Posted: Tue Jul 13, 2010 1:50 pm
by LTLFTcomposite
AndyH wrote:Too many guess without facts, gents! ...
Andy
We think we know that the "emergency" 120v cord plugs into the J1772 connector. But do we know if it actually does pilot signaling or does the car just have some default behavior when 120 volts appears on the pins unannounced? (eg start suckling at 12 amps) And if so, what is there a similar behavior in Europe, but at 240volts?

Re: EVSE source current

Posted: Tue Jul 13, 2010 2:46 pm
by johnr
LTLFTcomposite wrote:
AndyH wrote:Too many guess without facts, gents! ...
Andy
We think we know that the "emergency" 120v cord plugs into the J1772 connector. But do we know if it actually does pilot signaling or does the car just have some default behavior when 120 volts appears on the pins unannounced? (eg start suckling at 12 amps) And if so, what is there a similar behavior in Europe, but at 240volts?
To conform to the J1772 spec standard, the car *must* refuse power if no data signal is detected or the data signal is out-of-bounds. So, I'm sure the emergency L1 EVSE does pilot signaling. Furthermore, it sounds quite possible that the emergency L1 EVSE may be able to be plugged into a 240V source with little modification, making it into an "emergency" L2 cord in effect. But of course this is all speculation for now.

Re: EVSE source current

Posted: Tue Jul 13, 2010 2:59 pm
by LTLFTcomposite
johnr wrote: To conform to the J1772 spec standard, the car *must* refuse power if no data signal is detected or the data signal is out-of-bounds. So, I'm sure the emergency L1 EVSE does pilot signaling.
Right. It's not like the hardware guys would take a shortcut conforming to the standard just to save a buck.