Using nema 10-50 connector with single phase for Tesla charging?

[Diggler]

I'm wanting to do an EV charger hookup as easy and cost effective as possible. Probably only use it a couple weekends a year at a cabin site far from the grid. I've read as much as could and watched hours of YouTube. I have plenty of solar panels, but haven't bought an inverter yet. I had been looking at getting a split phase to charge only when the sun shines. I recently ran across a nema 30tt plug adapter (older travel trailer connection) that a Tesla will charge at 24 amps on 110v. From some reading, the Tesla chargers will accept 32 amps on 110v, maybe more amps. I understand enough to know that amps X volts is watts, so wether the car is charging at 240v at 15 amps or 110v at 30 amps, the car is getting the same wattage.
So, if you have a 6000w inverter, you could do 240v 30 amp or 110v 60 amps. If the cars accepts higher amperage 110v, why do people do split phase?
Second question is, knowing higher amps and lower voltage demands thicker wiring, can you use a nema 10-50 cable without one hot as that's the standard Tesla connection? If I could get 35 amps from 110v safely to charge, I'd be set.
Thoughts?
Also someone needs to do a slow DC charger that hooks directly to solar so people don't have to spend hours searching this stuff.

 

[hwy17]

240v 30 amps and 120v 60 amps is the same amount of power.

 

[Ampster]

If the cars accepts higher amperage 110v, why do people do split phase?

Because 240 Volts is more efficient and for the typical split phase inverter it is balanced between the legs. Many split phase inverters cannot handle 60 Amps of unbalanced load.

 

[Diggler]

240v 30 amps and 120v 60 amps is the same amount of power.

Correct. That's my question. Split phase inverters are about twice the cost.
I did find the wiring for a Nema 10-50 on the Tesla forum. Seems easiest to wire a 10-50 receptacle this way and use a single phase inverter.

 

[hwy17]

Split phase inverters are about twice the cost.

Twice the cost of what? An AIMS 120v or something?

Seems easiest to wire a 10-50 receptacle this way and use a single phase inverter.

So out of spec wiring of a 120v hot and neutral to the hot plugs of a 10-50? And expect it to draw 35 amps at 120v? I doubt that will work.

I just don't understand what you're trying to avoid or save here. Please provide some comparison examples of how you're arriving at this conclusion.

 

[Ampster]

I just don't understand what you're trying to avoid or save here. Please provide some comparison examples of how you're arriving at this conclusion.

I agree. In the larger scheme of things, my main service panel is 240 volt split phase and my AC coupled micros are actually 240 volt single phase with no neutral so whatever I can do at 240 volts is a lot more efficient. I iactually rarely charge my EV from the hybrid inverter but I do charge from excess solar during the day but most of that energy is passed through the hybrid inverter from my 240 volt micros to my EVs. Do we even know if they typical EVSE designed for 240 volts will work off one leg and neutral? I know the Tesla Wall connector and some of the other EVSEs I have used, do not even use the neutral so there is no way that I can imagine many of them would work.

The Telsa Mobile connector can use a TT30 for 120 volts but that is only 24 Amps at 120 volts or 2.9 kW and not the power the OP was hoping to get. The screenshot he posted clearly said the amperage in the car had to be set to 24 Amps and the TT30 adaptor on the mobile connector presumably sets it to use120 volts. The OP said he had lots of panels but did not specify so that is an unknow part of the calculation. Hopefully to get 2.9 kW of power he knows that he would probably need more than 4kW of solar panels?

I do realize this is the off grid section and the use case is a couple of weekends a month. I still see a 240 volt system as a much more efficient use of capital than all the workarounds one would have to do to save a little money by buying a 120 volt inverter. I charge from excess solar at 20 Amps 240 volts many days.

 

[Diggler]

Let me clarify.
Tesla used to sell adaptors for the 30tt up until 2016 or so as this outlet was common in rv parks in addition to the 10-50 Nema. The adapter uses the wiring that was shown with one hot, a ground and neutral to a Nema 14-50. They suggested charging at 24 amps as that was 80% of the max amps for 30tt. Larger current would blow the breaker and it wasn't designed for higher current. You can still buy the connector from 3rd party. In the charging desert where I go, there is a location that only has this 30tt outlet and was going to buy the adapter in case I needed to charge there in a pinch. I was unaware that a Tesla would charge at higher amps than 15 amps on 110v when I read up on the 30tt. I read that Tesla would accept over 40 amps on 110v. So I thought if I used a 30tt receptacle and the 10-40 adapter I could use a single phase inverter and charge at 24 to 30 amps. But why use an 30tt to 14-50 adapter, when you just wire it the same way Tesla does through the 14-50? Will Prowse showed how he wired a 14-50 direct to a split phase 6000kw inverter and would charge at 20 amps.
That would be the same wattage as 110v at 40 amps. Will 110v @ 40 amps on a 14-50 wire be too much of a load? A 6kw inverter puts out 120 amps on 48v DC with the correctly gauged wires.

The least expensive split phase I find is the Eg4 6000xp at around $1500 shipped. A single 6kw inverter is around $700 or cheaper if you get used, and you'd have to buy 2 to get split phase. Plus, there's the whole neutral ground bond issues when doing this. The system would be semi portable, like Will Prowse's 3kw EG4 setup in the dolly, and 2 inverters add to that problem with a load center.
Just trying to charge my car 4 or 5 times a year in the summer where I'm 100 miles away from a good charger. Even at 24 amps I could get 100 miles of charge on a sunny day, even over 2 days would be fine.
I watched the guy who did the solar run across America with his Tesla and solar panels. He had so much gear with the panels, inverter and a 48v 100 amp battery. There has to be an easier way, why do solar DC to inverter AC to car DC? Should be able to plug solar panels into a charger and be done with it. I'm not the only one that is in this boat.
Thanks for the input. As you can tell, I don't know enough about this yet.

 

[Ampster]

Tesla used to sell adaptors for the 30tt up until 2016 or so as this outlet was common in rv parks in addition to the 10-50 Nema.

There are two versions of the mobile connector and if I remember correctly the adapter cable is different for each version. I also remember that the adapters had a resister or other device in them that told the mobile connector what current to set the Tesla at. I don't know if it also tells it what voltage. That is important to know because on the latest version there appear to be only three power connectors of which one is ground. There are also two low voltage connections which presumably do the configuration mentioned above. I have the latest version and bought the compete package and in that version there is no 30TT adaptor.

Will Prowse showed how he wired a 14-50 direct to a split phase 6000kw inverter and would charge at 20 amps.

I presume Will Prowse's wiring of a 14-50 connector was using 240 volts. Charging at 20 Amps with that connector is no magic since I can set the charging rate in my Model Y to 20 Amps even though I am plugged into a 60 Amp Wall Connector.
None of the above means that you will be successful in charging at 120 volts at more than 15 or 24 Amps. The reason I mentioned the two power connectors is that in order to charge at 120 volts, one of those has to be configured to be a neutral and that is the issue or hypothetical that needs to be confirmed before investing in a 120 volt inverter in which you hope to charge at 24 or more Amps. That would not be hard to do at the park in the desert. which you mentioned in your comment. I am not trying to rain on your parade, I am trying to make you and other future readers aware of the issues which I see, in order to save you the expense of a mistaken inverter purchase without testing your assumption that it would work as you expect it to work.

 

[Diggler]

Or even easier, remove the 30tt plug on the adapter to a gen 1 or 2 adapter, wired straight to the inverter and you get thermal protection added?

 

[Ampster]

If I were doing that, instead of risking that I would mess up the device that tells the Mobile Connector the kind of plug I was using which might disable the Mobile Connector for that plug, I would make a pigtail to a TT30 receptacle. That does not test the assumption that you can charge at a current exceeding 15 or 24 Amps before investing in an Inverter. I have had some EVSEs not work even with a split phase UL listed inverter. I still have not heard how many kWs of solar you plan on installing and that should inform how much current any type of inverter can put out. A good ballpark is 75% of STC rating for five hours with good orientation and tilt and no shade.