Only 12A on NEMA 10-30 outlet

[jvellone]

Hi there,

I received a Tesla mobile connector with my Model Y and purchased the NEMA 10-30 adapter to plug into the dryer outlet at my parents' house when I'm there, often taking care of my mom. I'm not an electric engineering expert, but was expecting just below 30A from a NEMA 10-30 outlet - but as you can see from this screenshot, the most I'm getting is 12A - meaning that instead of the 5 or 6 kW of power I'm only getting about 2 or 3.

Any ideas as to what could be happening here? Could this be an issue with the mobile connector, or with the circuits at my parents' house? For context, the weather's been in the 50s (Fahrenheit) so not exceedingly cold.

I'd appreciate your ideas/inputs and apologize if I'm missing something fairly basic here. Happy new year to you all!

 

[exxxviii]

Did you get a Tesla NEMA 10-30 pigtail for the charger? That is what tells the charger what kind of circuit it is on. Your charger thinks it is only on a 15A circuit (max 12A showing). If it properly recognized the circuit, it would be max 24A, like “xx/24.”

 

[Tdriver]

A 10-30 should be able to supply 24A at 240V. Make sure there is no flashing red lights on the controller.

 

[exxxviii]

purchased the NEMA 10-30 adapter to plug into the dryer outlet

if you got something like this, it definitely won’t work and would explain your display:

 

[jvellone]

Yes, I did get the official Tesla 10-30 pigtail adaptor. The "T" on the mobile connector is flashing red while the other letters flash green. Any idea what could be going on and why it thinks the 30A circuit is only 15A?

 

[exxxviii]

What’s the flash pattern of the red light? Here’s the decode from the Gen 2 charger manual (page 13):

https://www.tesla.com/sites/default/files/downloads/gen_2_mobile_connector_owners_manual_32_amp_en_US.pdf

 

[ucmndd]

Yes, I did get the official Tesla 10-30 pigtail adaptor. The "T" on the mobile connector is flashing red while the other letters flash green. Any idea what could be going on and why it thinks the 30A circuit is only 15A?

Are you sure it’s completely inserted into the mobile connector? They need a pretty good shove to seat fully.

 

[jvellone]

Yes, I gave it a good shove. Mobile connector is display ing 4 red flashes, which indicates high temperature in the wall plug. Thanks for sharing the manual, that's what I was missing. Will have an electrician come by to see what's going on and provide an update for the community's benefit!

 

[ucmndd]

Yes, I gave it a good shove. Mobile connector is display ing 4 red flashes, which indicates high temperature in the wall plug. Thanks for sharing the manual, that's what I was missing. Will have an electrician come by to see what's going on and provide an update for the community's benefit!

Does it start at a full 24 amps and then eventually back off to 12? If so, that’s probably a real temp issue.

If the connector is flashing immediately when you start charging and immediately limiting the charge to 12 amps, I’d actually suspect you have a bum adapter.

Anything warm/hot to the touch after you’ve been charging for a while? I’d personally do a bit more troubleshooting before calling out an electrician.

 

[240vPlug]

that's only one phase of your 240v 30 amp circuit. Either a problem with the mobile connector or one open hot on the circuit.

 

[jwharnish]

usually when only getting 12 amp on a 30 amp plug, means overheating at the plug. Since you got Tesla adapter, I would take a good look at the plug. Cheap plug not advised, and connections may not be tight. Should be able to get 24 amps with that setup.

 

[ucmndd]

that's only one phase of your 240v 30 amp circuit. Either a problem with the mobile connector or one open hot on the circuit.

No, as OP’s picture clearly shows the car is getting 245 volts.

 

[240vPlug]

No, as OP’s picture clearly shows the car is getting 245 volts.

I see that now . Well that eliminates a problem with the circuit.

 

[Harriscott]

uhm. I use an emery board (nail file) cut down to fit, to "brighten" the contacts (which alas cannot be seen). That might help. Might be best to turn off power first.

update: do check if the outlet is hot to the touch when in use. That is a big red flag.

 

[BobCat]

Thank you. I've had a Y for 2 years and didn't know about this manual. I'm glad I finally learned how to use the Forum.

What’s the flash pattern of the red light? Here’s the decode from the Gen 2 charger manual (page 13):
https://www.tesla.com/sites/default...bile_connector_owners_manual_32_amp_en_US.pdf

I

 

[Art84]

The application is showing 12/12A. The first number is a current amperage, the second number is the max amperage limited by hardware. Since the second number is 12, it means that for some reason, tesla, or tesla charger limits the max limit to just 12A. Something tells the car, that connected circuit does not support more than 12A. Usually, it's the Tesla adapter, which you connect to mobile connector, that informs car that "hey, we can't pull more than 12A from this circuit". In case of tesla Wall Connector, it's the settings in the wall connector, how much can be pulled.

I know this is probably a rare case, but I think something is wrong with the Tesla adapter, connected to the mobile connector. It gives the wrong max charge limit for some reason.
If this would be an overheating problem, then an application would show 12/24A. So the circuit is recognized as 24A max, but the charging speed was reduced because of the high temp

 

[exxxviii]

I think something is wrong with the Tesla adapter, connected to the mobile connector. It gives the wrong max charge limit for some reason.

Only 12A on NEMA 10-30 outlet

Hi there, I received a Tesla mobile connector with my Model Y and purchased the NEMA 10-30 adapter to plug into the dryer outlet at my parents' house when I'm there, often taking care of my mom. I'm not an electric engineering expert, but was expecting just below 30A from a NEMA 10-30 outlet -...

teslamotorsclub.com

 

[ucmndd]

I know this is probably a rare case, but I think something is wrong with the Tesla adapter, connected to the mobile connector. It gives the wrong max charge limit for some reason.

When the car backs off the current due to an over temp condition, like the UMC error code is signaling, the current display in the car will look like this.

That could be due to a bad sensor in the plug head, or it could be due to an actual overheating outlet. No way to know without further troubleshooting.

 

[STS-134]

I'm not an electric engineering expert, but was expecting just below 30A from a NEMA 10-30 outlet - but as you can see from this screenshot, the most I'm getting is 12A - meaning that instead of the 5 or 6 kW of power I'm only getting about 2 or 3.

You won't ever get 30A from a 30A circuit. Charging an EV is considered a continuous load (a load that can be sustained for 3+ hours) and by code, continuous loads are limited to drawing 80% of the capacity of the circuit. On a 30A circuit, that means you'll get 24A.

Yes, I gave it a good shove. Mobile connector is display ing 4 red flashes, which indicates high temperature in the wall plug. Thanks for sharing the manual, that's what I was missing. Will have an electrician come by to see what's going on and provide an update for the community's benefit!

Most likely a loose or corroded or worn connector where the wiring attaches to the receptacle. You'll need to replace the receptacle and clean off the wiring if that's the case. Possibly (but less likely) a problem with the temperature sensor in the adapter. Does the plug feel warm when the issue occurs?

 

[Art84]

When the car backs off the current due to an over temp condition, like the UMC error code is signaling, the current display in the car will look like this.

Yeah, maybe you are right. But as far as I understand, the 12A is displayed right at the beginning of the charging. If this would be a thermal throttling because of the loose contacts or something, a drop to 12A would happen later in the charging cycle but not immediately