AndyH
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Re: EVSE source current

Tue Jul 13, 2010 3:02 pm

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?


Per the J1772 spec, any EVSE MUST provide a pilot signal. The spec is clear about what the EVSE sends to the car and how the car responds. It's back in post 2 - but posted again here.

This from June 19th...
http://www.mynissanleaf.com/viewtopic.php?p=7751#p7751

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

Bottom line - if the car is in compliance with the CURRENT J1772, it cannot charge without a pilot signal of some type. Either the car will receive a pilot signal between 10 and 97% to set the proper current limit, or it will receive a 5% pilot signal and know to listen for more instructions on the digital data signal (not the same as the pilot signal) (and not yet defined as that's in another SAE standard).

Note again the lines on table 6B for signals below 3%, between 7 and 8%, and over 97% - Error state , no charging allowed. No pilot = error state and charging cannot start.

Hypothetical detour...
We could guess that Nissan has found a way to be J1772 Jan 2010 compliant while allowing a straight extension cord connection for a 120V emergency charge. If they did that, and since they're supplying the 120V EVSE, and since they would have a larger profit if they could provide a 'dumbed-down' EVSE product, why would they include a full EVSE in the trunk bag rather than a $5 extension cord with a J1772 connector?

Then there's the down-side risk of shock (no EVSE means that the hypothetical hacked emergency cord would have live terminals when it's connected to 120V - illegal for J1772) and legal action from the 'unsafe' connection when clearly 'safe' products are available and in full compliance with J1772. I really don't think they'd take that risk.

Andy

edit...typo...$5 vice %5
Last edited by AndyH on Tue Jul 13, 2010 4:06 pm, edited 2 times in total.

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garygid
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Re: EVSE source current

Tue Jul 13, 2010 3:44 pm

The J1772 description of Control Pilot signaling (levels, frequency, PWM) applies to both L1 and L2 EVSEs and compliant vehicles.

So, no non-pilot defaults are described.
See SOC/GID-Meter and CAN-Do Info
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2010 Prius, 2014 silver Tesla S
Nissan EVSE, mod to 240/120v 16A
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AndyH
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Re: EVSE source current

Tue Jul 13, 2010 4:40 pm

garygid wrote:Charger AC current Requirement Example:

An efficient charger with a 120v AC input, putting 21 amps into a 75 volt (21 cells x 3.5 volts = 73.5 volts) battery makes about (21 x 75 = 1575 watts) of DC output.

So, the (maybe 94%) efficient (probably "switching" type) charger might draw about 14 amps (120 x 14 = 1680 watts) from the AC lines?

And, perhaps a little less if one actually has 124v AC instead of 120v?

That might explain why a 15-amp breaker does not "pop" when doing "21-amp charging". :)

Maybe my numbers are not perfect, but the general idea still holds.

Having 16 amps "allowed" gives us an extra 33% over the power we "are allowed" with the 12-volt max limit. So, 20-hour charging would drop to about 15 hours, and a "half" charge of 10 hours would drop to only about 7.5 hours ... possibly suitable for really useful 120v charging while at work.


Now do the math when I connect the ElCon '1500W' that's actually pulling 14A to the top of the 15A outlet and connect the Thunder Sky '60/15' that's pulling 13A from the bottom of the same outlet, please. :D

A 15A breaker, depending on temperature, can move close to 30A before tripping.

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Re: EVSE source current

Tue Jul 13, 2010 4:53 pm

AndyH wrote:Too many guess without facts, gents! ...
...
...
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

But changing Nissan's 120V *included* ("free") emergency L1 EVSE to pull the same 12A at 240V would be even cheaper :) while cutting charge-time in half.
2011 Silver SL+QC [Mfg: 11/2010] 36mo/15k LEASE
06Jun2013 Status [28.5 months][34,173 miles][11 bars]
Lost CapacityBar 6/6/13 @34,173 miles while in LEAF Battery Monitor: 83.41%, 71.4F (avg); cool overnight;

AndyH
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Re: EVSE source current

Tue Jul 13, 2010 4:54 pm

garygid wrote:The J1772 description of Control Pilot signaling (levels, frequency, PWM) applies to both L1 and L2 EVSEs and compliant vehicles.

So, no non-pilot defaults are described.


I'm not sure I understand what you're trying to communicate here, Gary.

"no non-pilot defaults are described"

The Jan 2010 J1772 spec clearly defines the full range of pilot signals created by the EVSE and sent to the car, as well as the required response from the car.

A 'non-pilot' situation might mean the wiring is connected but the duty cycle is 0%. It could also mean that there is no pilot line connected. Let's look at both scenarios from the perspective of the spec.

Valid wiring, 0% duty cycle.
This is clearly explained in Table 6A on page 16.
From the EVSE perspective: Duty Cycle < 5% is an Error State - No Charging Allowed
From the car perspective: Duty cycle < 3% Error State - No Charging Allowed

Invalid or incomplete wiring.
The car and EVSE share three lines to communicate switches and the pilot - ground, the pilot signal line, and the 'proximity switch on the EVSE connector is closed' line. All three must be present for charging to begin. If one or more of the three lines is not connected, the EVSE control box is not able to close the power contactor to feed AC to the charger. If the proximity switch (confirmation that the charge connector is seated and latched into the car) isn't closed, the car's charge controller does not close it's 'ready' switch (communicates ready status to the EVSE) and doesn't activate the car's charger. (See pages 11 thru 16.)

AndyH
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Re: EVSE source current

Tue Jul 13, 2010 4:56 pm

LEAFer wrote:
AndyH wrote: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

But changing Nissan's 120V *included* ("free") emergency L1 EVSE to pull the same 12A at 240V would be even cheaper :) while cutting charge-time in half.


If the 'EVSE Guts' can handle the increased current then absolutely - the price is right for this option!

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garygid
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Re: EVSE source current

Tue Jul 13, 2010 5:05 pm

Sorry, I meant "no USEFUL non-pilot...".
Thus, no useful "trivial" EVSE substitutes.
See SOC/GID-Meter and CAN-Do Info
2011 LEAF, sold in 2015
2010 Prius, 2014 silver Tesla S
Nissan EVSE, mod to 240/120v 16A
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Re: EVSE source current

Tue Jul 13, 2010 5:11 pm

AndyH wrote:
LEAFer wrote:
AndyH wrote: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

But changing Nissan's 120V *included* ("free") emergency L1 EVSE to pull the same 12A at 240V would be even cheaper :) while cutting charge-time in half.


If the 'EVSE Guts' can handle the increased current then absolutely - the price is right for this option!

You mean increased VOLTAGE (not current) ... :)
2011 Silver SL+QC [Mfg: 11/2010] 36mo/15k LEASE
06Jun2013 Status [28.5 months][34,173 miles][11 bars]
Lost CapacityBar 6/6/13 @34,173 miles while in LEAF Battery Monitor: 83.41%, 71.4F (avg); cool overnight;

AndyH
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Re: EVSE source current

Tue Jul 13, 2010 5:20 pm

LEAFer wrote:
AndyH wrote:If the 'EVSE Guts' can handle the increased current then absolutely - the price is right for this option!

You mean increased VOLTAGE (not current) ... :)


Well... Will you accept yes and no? :lol:

Sorry...I answered the question thinking about using an assumed 120V 12A EVSE for 120V 16A. :?

The EVSE appears to use a separate power supply of a bit over 12VDC. We might want to check that before connecting to 240V. We may have to provide our own separate 12V source.

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Re: EVSE source current

Tue Jul 13, 2010 5:36 pm

AndyH wrote:The EVSE appears to use a separate power supply of a bit over 12VDC. We might want to check that before connecting to 240V. We may have to provide our own separate 12V source.

Are you surmising ... in the guts of the (simplified) emergency EVSE they assume 120V AC input, and use that to create 12VDC (and possibly 5VDC) to power the micro-controller ? Hmmm ... yes that could present a problem. (I was hoping for zero mods of the guts.) So, unless they design the US, Euro and Japanese versions input voltage tolerant and with PSU components that auto-adjust ... :(
2011 Silver SL+QC [Mfg: 11/2010] 36mo/15k LEASE
06Jun2013 Status [28.5 months][34,173 miles][11 bars]
Lost CapacityBar 6/6/13 @34,173 miles while in LEAF Battery Monitor: 83.41%, 71.4F (avg); cool overnight;

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