LEAF L2 @ 208VAC - How nuch current?

[TomT]

At 110-120 it will pull a maximum of 12 amps. At 208-240, it will pull a maximum of 16 amps. That is limited by the charger itself regardless of what the EVSE says it can supply. So, yes, the wattage at 208 is lower than the wattage at 240 and will take a little longer to charge. Assuming that the EVSE says via pilot it can supply at least as much as the charger in the car can accept, the charger is the entity that controls the amperage drawn regardless of the voltage (12 amps at 1xx and 16 amps at 2xx)...

What will it pull if 30 amps is offered at 208? I think we know it will not pull more than the max offered.

 

[LEAFer]

EVChargerNews.com lists the Voltage at all sites. Maybe someone should run a LEAF over to a highway 101 RaboBank location (most are 208V nominal) with clamp-on ammeter for verification.

See here: http://www.teslamotorsclub.com/attachment.php?attachmentid=1966&d=1307902631

 

[EVDRIVER]

Even if it could pull 25A the wire in the LEAF is not even rated to handle higher current, only on the L3 port.

 

[tps]

At 110-120 it will pull a maximum of 12 amps. At 208-240, it will pull a maximum of 16 amps. That is limited by the charger itself regardless of what the EVSE says it can supply.

Where did you find this information? Or did you measure it?

 

[tps]

Maybe I'm getting an answer (of sorts) in the EVSE forum's 120V / 17A thread... Line voltage has been low at the office the past couple days; the 208V has been down into the mid 190's. They seem to be coming to the conclusion I thought all along: the charger increases current, if the pilot allows it, to maintain wattage at a lower voltage.

 

[garygid]

If the EVSE only offers 16 (or 12) amps, the EV should NOT draw more than 16 (or 12) amps, or the EV is NOT complient with the J1772 "sugested standards".

If the EVSE offers 16A, the EV is permitted to pull UP TO 16A at any voltage, if the charger in the EV can handle the power, current, and voltage.

Pulling 14 amps when offered only 12 is ... OUT of SPEC.
Pulling 17.8 amps when offered only 16 amps ... is also OUT of SPEC.
This is true at ANY input voltage, 90, 120, 200, 208, 240, etc.

 

[lincomatic]

If the EVSE only offers 16 (or 12) amps, the EV should NOT draw more than 16 (or 12) amps, or the EV is NOT complient with the J1772 "sugested standards".

If the EVSE offers 16A, the EV is permitted to pull UP TO 16A at any voltage, if the charger in the EV can handle the power, current, and voltage.

Pulling 14 amps when offered only 12 is ... OUT of SPEC.
Pulling 17.8 amps when offered only 16 amps ... is also OUT of SPEC.
This is true at ANY input voltage, 90, 120, 200, 208, 240, etc.

Yes, you are totally correct. The only qualifier I would like to add is that it is possible to design an EVSE to offer different current values depending on input voltage. For instance, 12A @ <=120V and 16A @ >200V. It's really up to the design of the hardware and software.

If the assertion is correct that the Leaf ups the current to meet its wattage limit, then it's possible that it is capable of pullling > 16A for L2 charging when the voltage is below 240V. If this is the case, then having and EVSE that can supply > 16A for L2 charging could be beneficial in houses that have unusually low line voltage. For instance, assuming that the Leaf limits to 16A @ 240V = 3840W, to get 3840W @ 208V the Leaf would need to draw 18.46A. So a person with 208V line voltage would benefit with an EVSE which could supply 20A rather than 16A. With a 16A L2 EVSE, the Leaf would only pull 3328W.

I've tested my theory for L1 charging, and it seems correct. I aim to test it out for L2 charging once I get my 240V line installed. Unfortunately, that won't be until sometime in August. If anyone has an L2 charger and a current clamp meter, we can put this to rest. It is quite possible that the wiring in the Leaf can handle only 16A. If this is the case, then it won't try to pull more than 16A for L2 charging. (of course, this doesn't explain why mine was pulling 17A for L1, but I'm assuming that it wasn't designed to do that).

 

[tps]

If the EVSE only offers 16 (or 12) amps, the EV should NOT draw more than 16 (or 12) amps, or the EV is NOT complient with the J1772 "sugested standards".

If the EVSE offers 16A, the EV is permitted to pull UP TO 16A at any voltage, if the charger in the EV can handle the power, current, and voltage.

Pulling 14 amps when offered only 12 is ... OUT of SPEC.
Pulling 17.8 amps when offered only 16 amps ... is also OUT of SPEC.
This is true at ANY input voltage, 90, 120, 200, 208, 240, etc.

All of what you say is true. As the OP, my intention is to determine if when using a charging station which offers 20A, such as the CC LCS-25, the LEAF will pull more than 16A charging from a 208V source. I'm not sure why this thread keeps repeating that the LEAF will not pull more current than offered; I knew that before I made my original post and I and others have made it clear repeatedly that we know the LEAF is limited by the pilot's current offering.

How much current does the LEAF pull at 208V WHEN THE PILOT'S OFFERING IS 20A OR GREATER. (Sorry to shout, but maybe that will bring this thread back on track.)

 

[LEAFer]

How much current does the LEAF pull at 208V WHEN THE PILOT'S OFFERING IS 20A OR GREATER. (Sorry to shout, but ... )

I said it on "Tue Jun 28, 2011 8:03 pm" above ... and I'll say again: go to a Rabobank on 101 corridor. I don't have an ammeter, but discovered that the Sacramento Courtyard By Marriott ChargePoint at CalExpo also is 208V nominal (and less under load) ... so ... OFF TO THE RACES, guys !! Who will be first to report ?

(Rabobanks at Santa Maria & Salinas; SanLuisObispo Marsh Street Parking structure.) (There are others listed in my above referenced post, specifically with 208V nominal.)

 

[brownga]

My owners manual on page 9-4 for the charging system specifications says:
maximum rated current 12A (120v), 18A (240V)
maximum power consumption 1.4kVA (120V) 4.8kVA (240V)

so if the EVSE will supply more than 16A, and most will, it seems that the charging system may draw up to 18A. Still confused about the 4.8kVA (240V) which would be 20A not 18A.

 

[TEG]

It seems the ChargePoints are showing me something like 3.7kW when I charge at them regardless is 240V or 208V. I think that works out to ~18A for 208V, and ~16A for 240V... So I vote that 18A is correct for 208V charging.
If it can pull 3.7kW, why do they call it a 3.3kW charger? Because of efficiency loss to the output?

 

[surfingslovak]

...why do they call it a 3.3kW charger? Because of efficiency loss to the output?

Yes, that's my understanding as well. I've been using 85% charger efficiency when evaluating the data sets folks posted on the forum, which worked pretty well. In this particular case, we are looking at 3.3 / 3.7 = 0.89. Seems to be 5% off.

 

[Coffee_Slurry]

My utility meter has only the Blink EVSE on it, and a charge looks like this:

 

[davewill]

I said it on "Tue Jun 28, 2011 8:03 pm" above ... and I'll say again: go to a Rabobank on 101 corridor. I don't have an ammeter, but discovered that the Sacramento Courtyard By Marriott ChargePoint at CalExpo also is 208V nominal (and less under load) ... so ... OFF TO THE RACES, guys !! Who will be first to report ?

Don't most current meters require access to individual conductors? I don't think there's any easy way to clamp on and measure current in the J1772 cable. Anyway, I'm convinced by the ChargePoint reporting 3.7kW when connected to 208v that the LEAF pulls the current needed to meet the charger's power rating, whether connected at 240v or 208v.

 

[planet4ever]

...why do they call it a 3.3kW charger? Because of efficiency loss to the output?

Yes, that's my understanding as well. I've been using 85% charger efficiency when evaluating the data sets folks posted on the forum, which worked pretty well. In this particular case, we are looking at 3.3 / 3.7 = 0.89. Seems to be 5% off.

Maybe 4% goes to the charger cooling system? I know that saying a quarter of the loss is in the cooling is a bit shocking, but that would be about 140 watts, which doesn't sound too outlandish for cooling.

Incidentally (and off-topic) 140 watt loss to cooling when doing L1 charging would be a 10% loss, which might explain (a) why people have reported lower efficiencies at 120v and (b) why Nissan pushes L2 charging so heavily.

Ray

 

[lincomatic]

Another data point showing that the Leaf violates the J1172 spec... even though my EVSE is telling the car not to draw more than 16A, it was pulling >18A the other day when my line voltage was running low again. I forgot to measure the exact voltage.

 

[tps]

Another data point showing that the Leaf violates the J1172 spec... even though my EVSE is telling the car not to draw more than 16A, it was pulling >18A the other day when my line voltage was running low again. I forgot to measure the exact voltage.

1. How do you know your EVSE is offering 16A? Did you measure the duty cycle of the pilot signal? Without knowing the duty cycle of the pilot, it's hard to know whether the LEAF is at fault or the EVSE is not operating as intended.
2. How did you measure the current? Can you give a closer value than >18A? How did you measure the voltage and what was it?

All of these findings could be quite interesting, but without more information, I'm not sure what to make of it... I centainly wouldn't jump to the conclusion that the LEAF is violating J1772, yet.

 

[lincomatic]

Another data point showing that the Leaf violates the J1172 spec... even though my EVSE is telling the car not to draw more than 16A, it was pulling >18A the other day when my line voltage was running low again. I forgot to measure the exact voltage.

1. How do you know your EVSE is offering 16A? Did you measure the duty cycle of the pilot signal? Without knowing the duty cycle of the pilot, it's hard to know whether the LEAF is at fault or the EVSE is not operating as intended.
2. How did you measure the current? Can you give a closer value than >18A? How did you measure the voltage and what was it?

All of these findings could be quite interesting, but without more information, I'm not sure what to make of it... I centainly wouldn't jump to the conclusion that the LEAF is violating J1772, yet.

1. I have a DIY EVSE. I am sure about how much current the EVSE is offering, because I measured the duty cycle with an oscilloscope. I have another thread about this issue.. the car was pulling >12A with L1 charging. I think it's a bug in the car. It controls wattage instead of current. So say the EVSE offers 12A for L1. It assumes 12A*120V is the wattage it's allowed to draw, and draws that wattage. It seems to track that, because if I set it to 6A and it's getting 120V input, it doesn't draw >6A. What they forgot is when you have a brownout, to get the same wattage, the current goes up.

2. I measure current with an AC current clamp meter. Granted, it's a cheap one from Harbor Freight, but I've tested several times when the voltage was around 240V, and the current was floating around <= 16A.
That's why I'm fairly confident about the >18A reading. As for voltage, I measure with a DMM for L2 and a Killawatt for L1 (for L1, I use the Killawatt as well).

I've been able to do sporadic testing because the line voltage at my house has been very erratic on hot afternoons, usually floating all over the place from 115-120, when my neighbors start turning on their AC's. Lately, it's been getting worse. The other day, it went down to 104V! I know it's due to my neighbors' usage and not my own, because during these episodes, my AC is off, and I'm using almost no power in my house.

What happened the day that I saw it drawing >18A was that the Killawatt was showing voltage < 115V .. unfortunately, I can't remember exactly what voltage, so I ran outside and hooked up the current clamp to see if the car would draw >16A, and it did. I should have measured the voltage at the EVSE but I didn't, because the last time I tried to measure both voltage and current simultaneously, they were both fluctuating in real-time. I have to switch the meter between voltage and current, so it's impossible for me to get the simutaneous readings. I don't have a watt meter that works w/ 240V.

For L1 charging, I was able to use the Killawatt to measure the wattage. I have tested with both my DIY EVSE set to L1/12A and the Nissan EVSE, which is set to 12A. With both devices, I have had instances Killawatt indicated it drawing more than 1440W (12*120). What happens is the Killawatt starts beeping, since it can't measure > 15A. Again, I couldn't calc the exact wattage since both voltage and current were fluctuating, and I could read only 1 at a time, but it was somewhere in the vicinity of 17A.

Unfortunately, I probably won't be able to do any more testing, because it appears that Edison has finally gotten around to fixing my low voltage. I complained to them, and it looks like they fixed it, because as of yesterday, my voltage is around 122V in the morning, and doesn't drop below 118V.

 

[tps]

Interesting... Next time I have the Hertz rental LEAF (or next year when I've got my own), I'll have to try some experiments. Maybe I come up with a transformer arrangement to run the voltage down to 200V or so. I've got a modified-for-16A Panasonic/Nissan unit from Phil. So what you're thinking is that, if I run the voltage down, the LEAF will draw more than 16A even if the EVSE pilot is set to 16A? (I guess I will have to dust off the o'scope to verify Phil did set the pilot duty cycle to 16A.) If this is true, yeah, the LEAF's charger is "broken". Probably won't be noticed, through, because the breaker ratings are normally so conservative because of the "80% rule" that in most voltage sags the breaker would have no problem holding at the increased current.

The reason I started this thread is to understand what we can expect from Ingineer's modified units at 208 volts. Mwalsh has reported power usage consistant with 12A/208V from his 12A EVSE. I saw 16A/240V on my 16A EVSE every time I used it.

One last question, at this point: How many charger control software versions are out the? The Hertz rental LEAF is early, VIN < 300, and my thinking is that Hertz has not trucked it back to Tennessee where they bought it to get the firmware updates. (The guess-o-meter seemed just the same when I rented it in July as it was in April.)

Thanks for the info!

 

[lincomatic]

Yes, what I am saying is that on several occasions of my Leaf was drawing > than the the current advertised by the EVSE, when the voltage is lower than 120V @ L1. It's quite reproducible. For L2, I've only noticed it happening once so far when the voltage was <240V, and haven't had a chance to investigate it further.

How did mwalsh measure the power?