Will not charge on 30 amp RV plug

Will not charge on 30 amp RV plug

Just got my M3 Black EAP 19" on Sunday. Was a big surprise since my delivery agent said mid next week and he would check with logistics... Not complain and grateful and glad I was home to accept.

So charging I have a 30 amp RV type plug on the outside of my house that runs my rv when I have it home to pack ( ac running ). So i know it works. I used the 30 amp to 50 cord from my rv to plug in my M3. Nothing... No Lights Car says ready to charge. So I swap to a 110 circuit and lights and car see power. So I buy a new 30 ==> 50 converter and this one has a light to show power. Nothing again on Tesla Charger and car says ready to charge. I am going to run a state park over the next couple of days and try their circuit but what am I missing? Car charged today at public EV station using J-1772 converter at 30 amp 15 mile / hr.


kevin_rf | September 24, 2018

You need a special third party TT-30 adapter to charge. Your RV 30amp is 120v at 30 amps, not 240v 30 amp. The wiring is slightly different.

A few people make them.... Here is a link to one:

btw. EVSEAdapters somewhere on the site says you will charge at something like 8 miles per hour with it.

Bighorn | September 24, 2018

Agree--the 120V makes this a trickier charge, but it is possible with the proper configuration.

MaxEV | September 24, 2018


Assuming you have the mobile connector, then it is recommended that you charge using one of the solutions described at this link:

For a 30 amp outlet, you need a NEMA 14-30 outlet and adapter. If your RV plug is a TT-30, that is not what you need if you want to use Tesla's adapters.

It has been reported that the NEMA 10-30 has been discontinued.

Until you get a proper higher amperage outlet, charge with your 120 AC adapter using the mobile connector that came with your car. If you have a new outlet installed, have a NEMA 14-30 installed or better yet a NEMA 14-50 put in if you can support it (or else have a Tesla wall connector installed).

al | September 24, 2018

Thank you. I am guessing on the 30 amp twist lock in the marine industry will require a special adapter as well? I am just wanting to cover all my bases.

Bighorn | September 24, 2018
Standroid | September 24, 2018

The outlet end of an "RV 30a to 50a adapter" looks just like like an NMEA 14-50R outlet, but it's not wired the same way. It's a very special adapter and cannot be used for anything other than an RV.

Large RVs that plug into a 240v/50a NMEA 14-50R outlet rarely use the 240v that is available across the two hot legs of a normal NMEA 14-50R. Instead, they treat each leg of the 14-50R outlet as a separate, isolated, 120v circuit. This allows them to spread the load across two circuits.

An "RV 30a plug to 50a adapter" takes the 120v/30a from an NMEA TT-30R outlet and connects that to BOTH legs of what looks like an NMEA 14-50R outlet. That provides 120v from each leg to neutral, but ZERO volts between the two hot legs because they are IN PHASE! It's a cute trick that works for many RVs, but it's totally useless for any other purpose - including EV charging.

Fortunately, our Teslas' are voltage-agnostic - they don't really care if the voltage supplied is 240v or 120v - they roll with anything. And, there is at least one "TT-30 Adapter for Tesla Model S/X/3 Gen 2" available that is wired for our Teslas (search for the text between the quotes and you'll find it). I haven't yet tried it, but it is alleged to work.

There are other (cheaper) TT-30 to NMEA 14-50 EV charging adapters that supply 120v across the two hot legs of the 14-50R outlet. That might work for our Teslas, but it could be dangerous if someone tried to use it with an RV (and those adapters look exactly like the RV adapter).

Caveat emptor!

Rocky_H | September 25, 2018

Folks are correct that camping supplies wire things in an entirely different way, so those "dogbone" kinds of RV adapter cables from TT-30 to 14-50 will never work for charging an electric car. I know there are a lot of old timers that are trying to be helpful, directing you to aftermarket TT-30 to 14-50 adapters for electric cars, but those require manually dialing down the current in the car, which you might forget, etc. etc. That is what we had to do 2 or 3 years ago, but EVSEAdapters was finally able to make real adapters for the 2nd generation Tesla mobile charge cable that just handle this directly.

So @kevin_rf has the right answer:
It's $75, which I know, seems a little pricey, but it is the right thing to get. It will automagically set the current to the allowed 24A from a 30A circuit without you needing to remember or do anything.

SION1771 | September 25, 2018

My TT-30 came with a big sticker on it saying to dial down the amps in the car before using. $45 on Amazon - maybe not worth the savings, but the EV adapters one is now discontinued.

Bighorn | September 25, 2018

I'd rather dial down the amps and retire early, but that's me.

kevin_rf | September 25, 2018

@SION1771 Is it discontinued, or as EVSEAdapters lists, temporarily out of stock?

SION1771 | September 25, 2018

@kevin_rf - sorry... I shouldn't pretend I know. I've read different stories on their situation so I'm not sure and assumed the worst.

Coastal Cruiser. | September 25, 2018

al, I would underscore what kevin_rf and Rocky said and go for the ESEAdapter.. if they come back in stock. You can also follow BigHorns' advice, but you must be a naturally careful person and remember to be sure the charge rate is manually lowered (or the car will try and draw too much current).

I have corresponded with the owner of EVSEAdapters in the past. I might just shoot him an email and see whats up with that TT adapter.


Coastal Cruiser. | September 25, 2018

BTW, EVSEAdapters is suggesting an alternate adapter until the "temporarily" out of stock Tesla adapter is in stock again. Unlike the out-of-stock adapter the substitute does NOT properly inform the car what outlet it is connected to, and the car will try and draw too much current! (unless you have manually dialed it back from the console).

Bighorn | September 25, 2018

If you set a current limit, it becomes geofenced forever. How many individual TT-30 or marine locations do you suspect someone will be using?

Rocky_H | September 25, 2018

"forever" defined as "until it isn't"

Coastal Cruiser. | September 25, 2018

BH, that was a nice little PDF you linked to. I like the actual photos of the outlets. Have you ever heard of someone installing a 14-60 in their garage?

SUN 2 DRV | September 25, 2018

Also if dialing back the current level isn't something you normally have to do at your normal TT-30 charging location (because you set it once a long time ago) you might easily not remember to do it at a new TT-30 location and then wonder why the car is tripping the breaker (or worse).

I agree getting the right adapter that always just does the right thing automatically it worth the extra expense.

Bighorn | September 25, 2018

I’ve not come across a 14-60.

Atoms | September 25, 2018

If you have a fire using non Tesla adaptors, you may have a hard time getting your insurance company to cover.
It would be a lot better to get an electrician and have proper wiring installed.

SION1771 | September 26, 2018

@Atoms, the evseadapters unit is also non-Tesla; there isn't a Tesla designed TT-30 option.