Fast Low Cost Charging - All EVSE Questions Answered!

[planet4ever]

and to compare vs the "I bought whatever Nissan told me to" L2 EVSE is
3.30 kW (220v x 15a = 3300 watts) "nominal" EVSE description apples to apples compared to the above

Nope, I don't think that is apples to apples. The AeroVironment or Blink EVSE can go much higher than 15A, much higher indeed than the V2 modified EVSE. The only limit with those two EVSEs at present is what the LEAF charger will do. That limit is the same regardless of what EVSE you use. I believe you are being confused by the 3.3kW rating of the charger inside the car. That appears to be an output rating rather than an input rating. So AeroVironment or Blink or whatever would be 3.84 kW at the wall, not 3.3 kW, when used to charge the 2011 or 2012 LEAF.

Ray

 

[dhanson865]

and to compare vs the "I bought whatever Nissan told me to" L2 EVSE is
3.30 kW (220v x 15a = 3300 watts) "nominal" EVSE description apples to apples compared to the above

Nope, I don't think that is apples to apples. The AeroVironment or Blink EVSE can go much higher than 15A, much higher indeed than the V2 modified EVSE. The only limit with those two EVSEs at present is what the LEAF charger will do. That limit is the same regardless of what EVSE you use. I believe you are being confused by the 3.3kW rating of the charger inside the car. That appears to be an output rating rather than an input rating. So AeroVironment or Blink or whatever would be 3.84 kW at the wall, not 3.3 kW, when used to charge the 2011 or 2012 LEAF.

Ray

so you think it would be fair to say the Modified L1/L2 Rev 2 EVSE would charge at the exact same rate as the wall mounted L2 EVSEs that are common?

 

[DaveinOlyWA]

yes. the power from the wall does not match the rating of the charger due to efficiency rating and active cooling overhead.

charging at;
A; 240 volt 16 amp = 85%
B; 240 volt 12 amp = 83.3%
C; 120 volt 12 amp = 75%

if you take the top figure 85% which btw is 3.3/3.84 that is why the charger is rated as such.

now my modded EVSE is metered http://www.mynissanleaf.com/blog.php?u=291&b=92" onclick="window.open(this.href);return false; and the 83.3 % is pretty consistent so i will take that is accurate. the 120 volt 12 amp was also monitored using Kill a Watt and several others here have reported the same figures.

so if looking at straight #s in each scenario above.

a; 3264 watt is going to car, 576 elsewhere
b; 2400 to car 480 elsewhere
c; 1080 to car 360 elsewhere.

now this is where it gets vague. i have to assume that different voltages will charge at different efficiencies simply because they generate different amounts of heat but several sources state the differences are small despite a nearly 300% difference in power levels.

the other thing to consider is time. now the 12 amp mod "should" take longer but it simply does not take very long which is the reason why i have forgone the 16 amp upgrade. maybe one of these days, but what i have now works just fine.

so what we dont really have is a good baseline on what the charge time is for each charging option (the car's estimate of time to charge is grossly inaccurate!)

so we can only assume by what we know.

in A if it takes 5 hours to charge or 5*3264= 16.32 kw
so B should take 16320/2400=6.8 hours and C would take 16320/1080= 15.11 hours.

so A would devote 5*576=2880 watts elsewhere, B 3264 watts and C 5439 watts

so there you have it. now, none of this mentions a charging method or brand or etc. its all just numbers. numbers that are both depressing and encouraging at the same time. despite being 200 to 300+% more cost effective to drive over the best of the gas options, there is a lot of waste going here but that means there is room for improvement

 

[tps]

so you think it would be fair to say the Modified L1/L2 Rev 2 EVSE would charge at the exact same rate as the wall mounted L2 EVSEs that are common?

On a 240V supply, the modified EVSE should charge at the same rate (slightly less than 16A draw) as an EVSE such as AV, etc. At 208V, the LEAF might draw a bit more than 17A if so offered, so the modified EVSE's 16A limit might be a bit slower. This is not likely to happen in the vast majority of homes, which are 240V single phase. 208V is normally seen in 3 phase commercial settings. That said, you might see 208V service at certain RV parks.

This shows what the modified EVSE draws at 240V:

 

[smkettner]

What happens if anything if an adapter is wired wrong. Specifically if a hot and ground were swapped. I am pretty sure it would not pass through power or charge Leaf but would the modified Nissan brick get damaged?

 

[DaveinOlyWA]

What happens if anything if an adapter is wired wrong. Specifically if a hot and ground were swapped. I am pretty sure it would not pass through power or charge Leaf but would the modified Nissan brick get damaged?

Could happen but breaker will likely tr IP before too much damage can be done

 

[EVDRIVER]

What happens if anything if an adapter is wired wrong. Specifically if a hot and ground were swapped. I am pretty sure it would not pass through power or charge Leaf but would the modified Nissan brick get damaged?

Could happen but breaker will likely tr IP before too much damage can be done

If you swap a hot with a ground then you will likely get 120V. It won't hurt the EVSE or the LEAF.

 

[garygid]

Wiring the Ground of an EVSE to a 120v Hot wire will instantly put 120v on the attached car's Ground.

Will the typical EVSE be able to detect that?

 

[tps]

What happens if anything if an adapter is wired wrong. Specifically if a hot and ground were swapped. I am pretty sure it would not pass through power or charge Leaf but would the modified Nissan brick get damaged?

This is very dangerous, since it would put voltage on the frame of the car as the equipment ground is not interrupted by the EVSE. It's also very unlikely to happen, as the ground screws and conductors are always clearly marked, usually green. If this mistake was made, the last thing I'd be worrying about in whether the equipment survives, I'd much rather see it provide some warning, even if that warning is equipment failure, before a person between the frame of the misconnected equipment and ground has a chance to become the failing part.

I think Phil covers all this in the agreement he has you sign, that this sort of stuff is only to be attempted by one who is competent to do so. Or verified by a competent person. If you feel there is any chance of a mistake, by all means let an electrician look at it before you plug it in!

 

[Ingineer]

If someone did wire a Hot to the EVSE's ground wire, it would indeed energize the body if the EVSE were also plugged into the car. Of course, the EVSE would not be powered, with no "ready" indication, so I only hope the idiot that does this doesn't add injury to insult by then plugging the EVSE into his car! :shock:

Usual Disclaimer: Don't try this at home, get it done professionally!

-Phil

 

[smkettner]

If someone did wire a Hot to the EVSE's ground wire, it would indeed energize the body if the EVSE were also plugged into the car. Of course, the EVSE would not be powered, with no "ready" indication, so I only hope the idiot that does this doesn't add injury to insult by then plugging the EVSE into his car! :shock:

Usual Disclaimer: Don't try this at home, get it done professionally!

-Phil

EVSE not powered? The modified Nissan unit would power up on the 120v between L1 & ground, yes?
I was curious if the circuit that tests for proper ground connection would be damaged. Or anything else in the modified Nissan brick.
I was looking for any confirmation that the modified Nissan evse was wired to protect itself.

Or would the ready light just stay off, or would the fault light come on.

I am not willing to test mine so I suppose we will need to wait for a post to see if the smoke comes out of it. :shock:

 

[Ingineer]

True, on 240v, it would power up the way you mention. Somehow I was thinking 120v.

Anyway, yes, the EVSE would survive such an event with no damage indefinitely. The ground current test would likely pass with flying colors, and the EVSE would be then operating at only 120v, and the GFCI is not going to trip. If you were wearing shoes when you touch the car, you might not ever know until you realize your car is only charging at 120v.

Very Dangerous indeed!

-Phil

 

[hpage]

Just for grins and giggles, I plugged my Nissan (upgraded) EVSE into my generator.. (even though I don't think my generator has the capacity). Didn't work -- green light was blinking - lack of ground(?).

Any ideas? Thanks!

Regards,

Howard

 

[garygid]

Usually the Generator Neutral and Ground need to be
connected together to get the EVSE to work ... right?

 

[Ingineer]

Usually the Generator Neutral and Ground need to be
connected together to get the EVSE to work ... right?

Correct

-Phil

 

[smkettner]

For 120v generator I think you are right Gary.
For 240v generator I don't know.

Easiest way to make a N-G bond (120v gen) is to get a replacement plug and connect the N & G terminals. Then just plug it in the other outlet.

 

[hpage]

Thanks!

 

[QueenBee]

This made me think about the safety implications of not having a portable generator be connected to a grounding rod/etc. It's apparently OK on a portable generator.
http://www.osha.gov/OshDoc/data_Hurricane_Facts/grounding_port_generator.pdf" onclick="window.open(this.href);return false;

"Bonding is the intentional connection between the grounded circuit conductor (neutral) and the grounding means for the generator, which includes the generator’s frame. Thus, effective bonding of the neutral conductor to the generator’s frame is also a concern for the safe use of the equipment."

So by default there isn't bonding between the neutral and the frame? If that isn't done what keeps a hot conductor from shorting to the grounding conductor, making the generator frame hot, and likely not tripping the circuit breaker?

 

[Ingineer]

So by default there isn't bonding between the neutral and the frame? If that isn't done what keeps a hot conductor from shorting to the grounding conductor, making the generator frame hot, and likely not tripping the circuit breaker?

Keep in mind, without a ground rod, there is no "reference" to ground, and thus a hot to frame is no different than a neutral to frame. I can see in small installations that isolation from ground could be actually safer in many fault scenarios.

-Phil

 

[QueenBee]

So by default there isn't bonding between the neutral and the frame? If that isn't done what keeps a hot conductor from shorting to the grounding conductor, making the generator frame hot, and likely not tripping the circuit breaker?

Keep in mind, without a ground rod, there is no "reference" to ground, and thus a hot to frame is no different than a neutral to frame. I can see in small installations that isolation from ground could be actually safer in many fault scenarios.

But if frame, grounding conductor, and neutral are all bonded then you'll trip the circuit breaker if hot and grounding short just like if hot and neutral short, right? Where as if the frame and grounding conductor are not bonded to neutral it is very likely that the circuit wouldn't trip.