While charging my EV (Electric Vehicle), Tesla model 3 long range, and watching all the other chargers not being used for the two hours I was there, I wondered if I could use two of them to charge faster. The chargers are greenlots ~200AC @ 30A. I know there are a lot of details that need to be consider ... like my car max. AC charging is limited to 48A (I think), wire gauge for the combined current, etc. I'm wondering about the technical stuff of combining two 60Hz (USA) AC signals only though. Thanks

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    \$\begingroup\$ As a yes or no answer, the answer is no. If you are asking if it is feasible to build a hack device that two chargers would recognize as legitimate EVs and successfully transfer energy to and your EV would recognize as a legitimate charger and be successfully charged by, the answer is perhaps. However in my opinion, providing guidelines for how to do that is not what we do here. Voted to close. \$\endgroup\$ – Charles Cowie Aug 24 at 17:21
  • \$\begingroup\$ I guess you missed this part in my post: "I'm wondering about the technical stuff of combining two 60Hz (USA) AC signals only" \$\endgroup\$ – Rodo Aug 24 at 17:56
  • \$\begingroup\$ I'm wondering about the technical stuff of combining two.... so what is your question? This is a question and answer site and questions that are answered yes or no are pointless. \$\endgroup\$ – Andy aka Aug 24 at 17:57
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    \$\begingroup\$ Afraid it's not that simple. The car communicates to the charger, and they negotiate a current limit. \$\endgroup\$ – rdtsc Aug 24 at 18:13
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    \$\begingroup\$ I didn't miss anything, I declined to answer the implied list of questions included in "wondering about technical stuff." \$\endgroup\$ – Charles Cowie Aug 24 at 18:19

Guess it would require one charger to be a master (comunicating with the car) and one or more slave chargers which need to be perfectly syncronized with the master. Thus the slaves need to messure the masters voltage and phase at the plug und control their own output to a very tight match, as already minimal differences in voltage and or phase will cause compensating currents between the chargers.

So from an engineering point, technical feasable? I think it is possible.

From a economical point (think such a solution adds quite some costs), customers which need to fiddle around with more adapters and cables, and reliability and security safety in 24/7 operation --> I guess No is the right answer.

But it might be of interest for a operator or manufacturer of chargers to have modular power stages and combine several of them internaly to match different power classes.

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  • \$\begingroup\$ Some DC fast chargers do something similar to this I believe. However, AC chargers are generally just safety contactors and ground-fault detection with some communication. They do nothing to the underlying power except switch it. \$\endgroup\$ – SomeoneSomewhereSupportsMonica Aug 25 at 8:06
  • \$\begingroup\$ @SomeoneSomewhereSupportsMonica If I understood the OP correct, he talks about charging with 200V ac @ 30A. As far as I know the US standard voltage is about 120V. To me this means the charger is converting from voltage x to 200. I know from public high power chargers in Germany that these are connected to a higher voltage grid of lets say 1000-10000V. And the size of the devices indicates the use of switched convertes not just a transformator... So there is more than just switch it, right? \$\endgroup\$ – schnedan Aug 25 at 8:42
  • \$\begingroup\$ The US has a vast number of different supply systems for historical reasons. It's likely that he's referring to two phases from a 120/208Y three phase system - 208V between phases. In Germany I would generally expect them to run off 400V three phase - no-one is directly using medium voltage that I know of. \$\endgroup\$ – SomeoneSomewhereSupportsMonica Aug 26 at 5:20
  • \$\begingroup\$ Often, the volume is just empty space to make it look big and for mechanical strength. Some of the space will be taken up with revenue meters, RCDs/MCBs, a small computer etc. There are some with converters onboard but these all output DC to the car. No-one is doing AC-AC conversion inside them. \$\endgroup\$ – SomeoneSomewhereSupportsMonica Aug 26 at 5:22
  • \$\begingroup\$ Well I know here in Germany when several chargers are build on site of motorway service stations mid voltage grid access is at least only a few meters away from the chargers. I would assume to directly attach them to the grid but maybe they use 400V and some thick cables. In terms of efficiency factor I guess the better solution is to directly use mid range voltages like 10kV \$\endgroup\$ – schnedan Aug 26 at 6:31

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