Fast Low Cost Charging - All EVSE Questions Answered!

[jpokoraw1]

so the outlet rating is the max amps the circuit will allow before the breaker trips? Help me out: Volts is a measure of how much power is present in a unit of energy... amps is the measure of how fast the unit travels in the current ... so, when an appliance is demanding more and more 220v units in the current... the speed of the 220v unit increases, which is measured as more amps...

 

[smkettner]

Volts is more like pressure, Amps like volume.
As long as 50 is available and you only pull out 16 you are good to go.

The 50a service could supply three LEAF for charging.

 

[GlennD]

So, you get the same charge rate from a 208V source as a 240V one, whether using a public J1772 or your 16A mod, right?

I charge at work on 208V and I have measured the current at 16A so it charges at 3.3KW instead of 3.8KW. Sometimes the 208 is really 210V so I get a small extra.

 

[smkettner]

I believe the 208 charging rate will be slightly lower than 240 volt. The wattage is lower assuming constant 16 amps.
And yes some RV park 50 amp connectors could well be 208 volts.

 

[Norway]

So, you get the same charge rate from a 208V source as a 240V one, whether using a public J1772 or your 16A mod, right?

I charge at work on 208V and I have measured the current at 16A so it charges at 3.3KW instead of 3.8KW. Sometimes the 208 is really 210V so I get a small extra.

The voltage (Volt) is the "pressure" available for pressing electrons into the charger. (This depends on the electricity supply.)

The current (Ampère) is the flow of electrons into the charger. The charger determines this.

The power (kilowatts or kW) is obtained by multiplying the current and the voltage. So 16 A and 230 V is approx 3.7 kW (the max the Nissan charger can take.)

If only 208 V is available, the charger will still not draw more than 16 A, so the power will be 3.3 kW.

 

[EVDRIVER]

I believe the 208 charging rate will be slightly lower than 240 volt. The wattage is lower assuming constant 16 amps.
And yes some RV park 50 amp connectors could well be 208 volts.

It is actually a fact, 208V X a fixed 16A = 3.328 kw.

 

[Randy]

It's been bugging me, and I haven't done any measuring, but we have a ChargePoint unit at work that is connected to 208v. The digital display says it is delivering 3,653 watts when charging my LEAF...That has to be a higher current than 16 amps if the display is correct...

 

[smkettner]

I have read posts where there seems to be some leaway for sagging voltage so I while I would expect 208 to be lower charging it may not be directly propotional to the 208/240 differential.

 

[DaveEV]

It's been bugging me, and I haven't done any measuring, but we have a ChargePoint unit at work that is connected to 208v. The digital display says it is delivering 3,653 watts when charging my LEAF...That has to be a higher current than 16 amps if the display is correct...

The LEAF will pull more than 16A on 208V if the EVSE says it can handle it.

 

[EVDRIVER]

It's been bugging me, and I haven't done any measuring, but we have a ChargePoint unit at work that is connected to 208v. The digital display says it is delivering 3,653 watts when charging my LEAF...That has to be a higher current than 16 amps if the display is correct...

Because that unit does not have a 16A pilot signal so it can go higher. The pilot signal of the EVSE always determines the max amp draw the charger is allowed, it will not increase past that figure regardless of the voltage.

 

[Deleted member 3147]

It's been bugging me, and I haven't done any measuring, but we have a ChargePoint unit at work that is connected to 208v. The digital display says it is delivering 3,653 watts when charging my LEAF...That has to be a higher current than 16 amps if the display is correct...

Because that unit does not have a 16A pilot signal so it can go higher. The pilot signal of the EVSE always determines the max amp draw the charger is allowed, it will not increase past that figure regardless of the voltage.

Just to further clarify:

1) At voltages around 120V, the on-board charger will not draw more than 12 amps, regardless of the pilot signal from the EVSE.

2) At higher voltages (I do not know where the change-over occurs), the OBC will attempt to get 3,840 watts (240 volts x 16 amps) and will vary the current depending on the actual voltage:

2a) At higher voltages, up to the limit (250 volts, I think Phil said), the OBC will draw less current.

2b) At lower voltages, the OBC will draw more current up to some limit, which is at least 18 amps but might be a little bit more.

IN ANY CASE, the OBC will never draw more current than is allowed by the EVSE pilot signal!

BTW, in general, if you apply too much voltage to a circuit, you have problems with arcing and component/insulation breakdown.

On the other hand, if too much current flows, things tend to heat up and, if they get hot enough, burn up. The main difference between a 20 amp household circuit and a 40 amp circuit, other than the circuit breaker, is the diameter of the wires. The purpose of a circuit breaker (over current protection device) is to prevent so much current from flowing that the wires will burn up and start a fire.

 

[bernie82]

Does the EVSE upgrade full speed $48 rev2 add on charge the Leaf in about the same amount of time as a L2 charging station?
Phil says that it wastes less energy than L2 charging stations. Does that mean my cost per recharge is reduced?

 

[DaveinOlyWA]

Does the EVSE upgrade full speed $48 rev2 add on charge the Leaf in about the same amount of time as a L2 charging station?
Phil says that it wastes less energy than L2 charging stations. Does that mean my cost per recharge is reduced?

you will see an increase in efficiency if going from EVSE mod level 1 (85%) to level 2 (~88%) and it matches public L2 stations which should run at 240 volts and 16 amps or 3840 watts. the reason the Charger is rated at 3.3 Kw (3300 watts) is due to overhead and efficiency rating, heat losses, etc. if penciled out that would be 86% (3840*.86)

keep in mind, the #'s are approximate as they are temperature sensitive. as far as the 85% on level 1 (240 volt, 12 amp) this is what i have and have verified the 85% as being very consistent.

the 88% figure is gleaned from posts here and users report the measurements from a variety of sources but the generally run from 87% to 90% with the corresponding variety concerning margins of errors.

i also have extensive records for 120 volt charging at 12 amps which showed an efficiency of 75%.

 

[planet4ever]

Dave didn't say it directly, but the loss in the EVSE is insignificant compared to the loss in the charger. If Phil says his EVSE is more efficient than other L2 EVSEs then I believe him, and it does make sense, but I don't think that would make a noticeable difference in what you pay for electricity, unless you leave it plugged in and unused for weeks at a time. As Dave indicates, there will be a noticeable difference between the Rev 1 and the Rev 2.

Ray

 

[ELROY]

Sent out my EVSE on Monday afternoon from Camarillo, which is 425miles away to Berkeley. They received the unit today (Weds) before noon and I was just advised they are sending it back out today. I should get it back before the weekend! I was requesting prompt service as I am down to 30% charge in my LEAF, but this service is even better than I could hope for. And they are right about UPS. Excellent electronic tracking and shipping all night/day. Thanks again guys, can't wait to have a much more useful charging/driving experience.

 

[EVDRIVER]

Does the EVSE upgrade full speed $48 rev2 add on charge the Leaf in about the same amount of time as a L2 charging station?
Phil says that it wastes less energy than L2 charging stations. Does that mean my cost per recharge is reduced?

Yes, the exact same time. It also has less parasitic draw than most.

 

[Deleted member 3147]

Does the EVSE upgrade full speed $48 rev2 add on charge the Leaf in about the same amount of time as a L2 charging station?
Phil says that it wastes less energy than L2 charging stations. Does that mean my cost per recharge is reduced?

Yes, the exact same time. It also has less parasitic draw than most.

Yes, the draw is less. However, the difference is so small as to be almost meaningless. You are talking maybe 5 watts difference, vs. > 3000 watts drawn while charging. If you leave the EVSE plugged in all the time, you're talking about less than 0.12KWh/day.

 

[EVDRIVER]

Does the EVSE upgrade full speed $48 rev2 add on charge the Leaf in about the same amount of time as a L2 charging station?
Phil says that it wastes less energy than L2 charging stations. Does that mean my cost per recharge is reduced?

Yes, the exact same time. It also has less parasitic draw than most.

Yes, the draw is less. However, the difference is so small as to be almost meaningless. You are talking maybe 5 watts difference, vs. > 3000 watts drawn while charging. If you leave the EVSE plugged in all the time, you're talking about less than 0.12KWh/day.

In PGE land that can be $24 a year- LOL.

 

[leonardvoet]

I just wired up my upgrade and plugged it into a 220v outlet and it's only charging at 120v and the green light on the charger is on.
Help!

 

[smkettner]

I just wired up my upgrade and plugged it into a 220v outlet and it's only charging at 120v and the green light on the charger is on.
Help!

If you are plugged into 240v then that is what is charging. There is no voltage reduction.

Is it possible you plugged into 120/240 volt service and misconnected an adapter to get 120v?

What exactly is the indication you are at 120v?