connections— 10-30 to L6-20

[Pawl]

Sorry for the confusion. I started this thread, but took some other yarn and have woven something entirely different. Learned a lot along the way!

 

[SteveC5088]

Does the EVSE need to be set [down] to the 20A, or does this matter? (Doesn't the onboard charger essentially tell the EVSE what to let through?)

No, it needs to be set (down) to the capacity of the j1772 plug and wires between the EVSE and the plug. That way, you won't burn out the plug or the cable.

The EVSE is not the controller here "letting through" a set amperage. The only thing that controls the amperage is the on-board charger in the car. The EVSE tells the charger what it can handle, and then the charger (if it works correctly) will not pull more than the amperage specified by the EVSE.

 

[Pawl]

Does the EVSE need to be set [down] to the 20A, or does this matter? (Doesn't the onboard charger essentially tell the EVSE what to let through?)

No, it needs to be set (down) to the capacity of the j1772 plug and wires between the EVSE and the plug. That way, you won't burn out the plug or the cable.

The EVSE is not the controller here "letting through" a set amperage. The only thing that controls the amperage is the on-board charger in the car. The EVSE tells the charger what it can handle, and then the charger (if it works correctly) will not pull more than the amperage specified by the EVSE.

Now I'm confused again. The cable between the evse and the plug are about 1 inch thick (or more) on this particular Juicebox EVSE; I don't think they'll be burning-out any time soon. So if the only thing that controls the amperage is the charger in the car, and if the aforementioned wires and plug are of [more than] sufficient capacity, then the outgoing amperage doesn't need to be lowered. In other words, assuming all the links between panel and charger—breaker, wires, evse, wires, j1772 plug—are of, let's say, 50A capacity, this passageway will not pose any undue stress on the charger, that the charger will only draw what it can draw (in the Spark EV's case, 16A), taking no heed of the amount of juice available.

 

[SteveC5088]

Now I'm confused again. The cable between the evse and the plug are about 1 inch thick (or more) on this particular Juicebox EVSE; I don't think they'll be burning-out any time soon.

When it comes to rating, the thickness of that cable can be misleading. It is actually the thickness of the copper INSIDE all that insulation that matters. And also, it is the capacity of the J1772 plug -- it sometimes has its own wires that the cable splices into. ...and even the quality of the couplings between the wires. My J1772 that I got from emotorwerks is rated at 32 Amps (stamped on the plug), even though the JuiceBox is supposed to handle 60 Amps.

So if the only thing that controls the amperage is the charger in the car, and if the aforementioned wires and plug are of [more than] sufficient capacity, then the outgoing amperage doesn't need to be lowered. In other words, assuming all the links between panel and charger—breaker, wires, evse, wires, j1772 plug—are of, let's say, 50A capacity, this passageway will not pose any undue stress on the charger, that the charger will only draw what it can draw (in the Spark EV's case, 16A), taking no heed of the amount of juice available.

The above is correct, except the "will not pose any undue stress on the charger". Actually, the stress would not occur to the charger if too much current were drawn to it through the EVSE and J1772 plug. The stress would occur to the wiring in the EVSE or plug. THEY would overheat, and the heat would cause damage by melting things. The charger in the car would be just fine. This is why a quality EVSE will have its own internal fuse, to prevent the expensive parts from overheating. The fuse would overheat first and blow out, protecting everything else.

The only way you could damage the onboard charger would be to somehow increase the voltage passed to it from the expected 120 or 240 to something much higher. THAT is practically an impossibility, unless you somehow hooked up to a totally mis-wired industrial installation, where higher voltages are sometimes available.

 

[Chocula]

SteveC5088 was just indicating that your EVSE also needs to be rated at or above whatever it gets set too.

You mentioned earlier that you have a "Jukebox 40 Pro", which I am assuming you meant "JuiceBox Pro 40" which I believe can be set as high as 40 amps. http://www.emotorwerks.com/products/online-store/product/show/202-juicebox-pro-40

You also mentioned 6/3 with a 50A breaker. Assuming your wiring was done correctly, your circuit is 50 amps so you can set your EVSE as high as 40 amps as your EVSE is rated for up to 40 amps. You can also safely leave it at the 30 amps it came pre-configured to. If you have any doubts about anything, confirm with your electrician and emotorwerks.

None of this will make any difference to your Spark, but your friends Tesla will charge a bit faster if you set it to 40 amps rather than 30.

 

[Pawl]

A big THANKS to all who've pitched-in and helped my understanding of all this. Much obliged!