Good article and comments re merits of higher amp Level 2 charging

[dadaleus]

Dual Head Schneiders just suck. Limited to 30A each @ 203vac (6kw). $3000 units designed with no vision, no joy.
--

I was not referring to existing dual heads. I was specifically responding to this:

...that can split the available power between the two heads according to what the vehicles currently plugged in are actually taking - 40:40 if both Model S, 80:0 if only one plugged in, 15:65 if one side happens to have a Leaf plugged in etc.

 

[swaltner]

There's a crying need for a dual-headed charger that can split the available power between the two heads according to what the vehicles currently plugged in are actually taking - 40:40 if both Model S, 80:0 if only one plugged in, 15:65 if one side happens to have a Leaf plugged in etc. It would be extremely easy to do, but I haven't seen any of the EVSE manufacturers offering such a thing [I'd be very happy to be proved wrong!].

Is the J1772 standard/protocol an on-going process, or is this a one-time negotiation when charging first starts. i.e., could an EVSE drop an in-progress charge session from 80 amps to 40 amps if needed? If so, it seems like this would be a relatively easy add-on. Add a couple current sensors and logic to the EVSE to make sure that the max-current isn't exceeded....

 

[arg]

Is the J1772 standard/protocol an on-going process, or is this a one-time negotiation when charging first starts. i.e., could an EVSE drop an in-progress charge session from 80 amps to 40 amps if needed?

I haven't read the J1772 specifications myself, but if you browse the OpenEVSE lists (here for example), people report that currently available cars do support it dynamically. And even if you find one that doesn't, the control logic can always terminate and re-start the charging session if it detects the car failing to reduce its draw when asked.

If so, it seems like this would be a relatively easy add-on. Add a couple current sensors and logic to the EVSE to make sure that the max-current isn't exceeded....

Exactly. So why are none of the vendors doing it?