Adapter to combine two 30A level2 into one 60A J1772 - faster charging

[efxjim]

The are two ways to pull a balanced load from each circuit. First is a transformer with two separate coils on the input side feeding one coil attached to the car. The separate coils are needed to insure the current coming from the hot is returned fully back through the other hot keeping the GFCI happy.This method would be very heavy and pricey. The other is a two input inverter that takes power from each source and feeds a DC buss and then converts that to AC for the car to convert back to DC!:scared: Since the car already has 2 AC to DC charging sources we would need to see if it is possible to feed the second inverter from a second source. That would be non trivial and void the warranty.

 

[FlasherZ]

The are two ways to pull a balanced load from each circuit. First is a transformer with two separate coils on the input side feeding one coil attached to the car. The separate coils are needed to insure the current coming from the hot is returned fully back through the other hot keeping the GFCI happy.This method would be very heavy and pricey. The other is a two input inverter that takes power from each source and feeds a DC buss and then converts that to AC for the car to convert back to DC!:scared: Since the car already has 2 AC to DC charging sources we would need to see if it is possible to feed the second inverter from a second source. That would be non trivial and void the warranty.

At some point, you have to wonder if it's just not better to sit back and enjoy a book with a longer charge time.

I just added two more questions to the FAQ, one dealing with this case and the other dealing with the easy-240 devices I see pop up now and then. Bottom line is that both approaches violate the NEC (and so may have insurance implications for you if something goes horribly wrong), but can be made safe with a lot of complexity and knowledge. You either have to teach the average non-engineering user of the Model S about phase alignment and path resistance and such, or the instructions have to include "keep plugging into a bunch of different circuits and see if you find something that works, in which case light A will be off (phase alignment), light B will be off (leg alignment), and meter C will read center (load distribution across circuits)."

Those of you who know what you're doing - good luck in the wild. Those who don't, I'll leave with a recommendation to stick to superchargers and 40A.

 

[jimbeault]

View attachment 8323Yes on the switch i have a diode then i think a 2.7k resistor and the switch adds a 1.3k resistor to close the contactor. I have two switches one for each inlet adaptor. I will work on a better drawing. Here is a CRUDE first iteration of the combiner.

The two rocker switches tell the charger to turn on, the two light switches (30A 3 way) allow me to change phase of the one J-1772 and the two lights tell me if there is voltage between the phases of the two J-1772 feeds.

Not quite shown, as it is resting on it are two 30 amp breakers hoping I would trip a one of the 30 amp breakers before the 40 amp breaker of the charge station would trip.

I was planning to limit to 54 amps to keep from overloading.

Did you end up having a fonctionnal setup?

 

[dhrivnak]

Did you end up having a fonctionnal setup?

Not that I recall after a number of tries. I wonder if the three phases on your typical 3 phase circuits were my main challenge. And since I now have a Model 3, I rarely use level 2 public charging. Even 60A would be very slow compared to SuperCharging.

 

[cdswm3]

I think this is a very dangerous experiment. You are dealing with high voltages and currents that are deadly. You would never be able to get any device like this approved by any certifying agency. Also no one wants an EV to occupy 2 changing stations. We need more locations not EV owners using 2 locations.