Only 8A on 240v? What am I doing wrong?

[MikeRTX]

I know this has been discussed to some extent awhile back, but my brand-new setup with Tesla Mobile Charger via NEMA 14-50 outlet running through a 240v 30A circuit won't let me go past 8A. Of course that's unacceptable, since my M3SR says that'll take me 24 hours to juice it up.

The outlet itself is UL rated and said to be "commercial grade". Bought at Home Depot. The only thing I've added to the mix is a Y-connector from my dryer outlet to the 14-50 outlet (converting it from NEMA 14-30 to 14-50 for the Mobile Charger plug.

What the heck? Ideas appreciated.

 

[SSonnentag]

Assuming everything is wired correctly, you should be safe to draw 24A with that setup, provided the dryer isn't running. Is the car showing 240+ volts while charging? Does the car/app give you the option to increase the charging current? Normally there is a <AMPS> (less or more) interface in the app as well as on the charging screen in the car.

In my example below, I have set our X to charge at 71A. I can increase or decrease the amperage using the interface.

WARNING: With your Y-cable adapter setup your car/app will allow you to set the charge current above the 24A that is safe for you to continuously draw. So be sure you don't set the amperage above 24A. Don't max out the charger to 32A (or 40A if you have an old charger) as it will overheat your wiring and blow a breaker or worse.

 

[jjrandorin]

I know this has been discussed to some extent awhile back, but my brand-new setup with Tesla Mobile Charger via NEMA 14-50 outlet running through a 240v 30A circuit won't let me go past 8A. Of course that's unacceptable, since my M3SR says that'll take me 24 hours to juice it up.

The outlet itself is UL rated and said to be "commercial grade". Bought at Home Depot. The only thing I've added to the mix is a Y-connector from my dryer outlet to the 14-50 outlet (converting it from NEMA 14-30 to 14-50 for the Mobile Charger plug.

What the heck? Ideas appreciated.

Mistake #1

Using a Y connector to connect the outlet. Since you dont mention buying a specific one that either has electronic switching in it, or adding a manual disconnect that would allow only one or the other to be used at the same time, this is not to code. It would be safer to unplug and re plug the adapter into the outlet than add a simple Y connector.

Mistake #2

Converting the outlet to a 14-50 outlet, and using the Tesla 14-50 adapter, when the actual outlet and wiring is a 30 amp outlet. Presumably you intended to depend on the car to turn down the amps to 24, but the 14-50 outlet being used on the adapter will signal to the car its plugged into a 50 amp outlet and its likely trying to set itself to 32amps.

There should not be a "Tesla 14-50 adapter connected to a 14-30 outlet" full stop.

Its likely dropping down to that charging speed because its overheating, and trying not to burn your house down.

 

[SSonnentag]

If your car decides to top up the battery while your dryer is running, bad things could happen. You really should look into a proper setup for charging.

 

[Sophias_dad]

I know this has been discussed to some extent awhile back, but my brand-new setup with Tesla Mobile Charger via NEMA 14-50 outlet running through a 240v 30A circuit won't let me go past 8A. Of course that's unacceptable, since my M3SR says that'll take me 24 hours to juice it up.

The outlet itself is UL rated and said to be "commercial grade". Bought at Home Depot. The only thing I've added to the mix is a Y-connector from my dryer outlet to the 14-50 outlet (converting it from NEMA 14-30 to 14-50 for the Mobile Charger plug.

What the heck? Ideas appreciated.

Make sure the adapter is fully installed in the UMC.

And take everyone's advice and don't use that Y connector.

 

[MikeRTX]

No guys, I know not to run the dryer and charge the car at the same time - that would just trip the breaker and/or burn my house down. lol.

I specifically wanted - and tried - to adjust the charge current down to 24A (80% of the 30A max), but again the car went to 8/8A immediately on plugging it in. It is showing 235v on my 240v line, so that's close enough. The charger housing itself is warm, and the cable to the car is also warm, but the line from the dryer plug to the outlet is nice and cool. The Tesla logo on the Mobile Charger housing is in animated green letters, except that the "T" starts out red before the other letters go green. The charge port logo on the car is flashing green while charging.

I'm wondering if maybe the Mobile Charger is wonky (?) I suppose the service center can test it for me (?) I found it odd that there were two other threads a year or so ago showing only 8A, too!

 

[MikeRTX]

Okay ... just unplugged the Y-adapter and plugged the line to the outlet directly into the 240v dryer outlet.

NO difference. The charge current is still showing 8/8A.

This would seem to point to the outlet, which is a Leviton 14-50 (to match up with the Tesla Mobile Charger cable dongle (the only one supplied for 240v application). Everything seems to accept the setup, but it just doesn't deliver enough Amps to get the job done.

Yeah, a wall charger would be nice to have, but I've already spent over $250 on this, and paying an electrician $6-700 for a wiring job and Tesla about the same for the wall charger is a bit more than my budget can handle. Others have made this work, so I'm scratching my head figuring out why mine won't!

 

[brkaus]

Try your connector elsewhere.

What does the charge screen say when the mobile evse is not plugged into the car?

 

[SSonnentag]

Sounds like an issue with the mobile charger to me. It's allowing charging and not showing any faults, so I don't know what else it could be.

 

[MikeRTX]

Try your connector elsewhere.

What does the charge screen say when the mobile evse is not plugged into the car?

 

[MikeRTX]

Sounds like an issue with the mobile charger to me. It's allowing charging and not showing any faults, so I don't know what else it could be.

Kinda thinking the same.

 

[Sophias_dad]

I'm not sure I'd blame the UMC yet. Its most likely either the adapter or the UMC, since the adapter is supposed to be telling the UMC what kind of adapter it is.

I'd wager the 'we don't know what adapter that is' behavior is to only charge at 8A. Is it an authentic Tesla adapter? Can you try it on someone else's UMC? Can you try the 120v/15A adapter on your UMC ?

 

[jjrandorin]

Okay ... just unplugged the Y-adapter and plugged the line to the outlet directly into the 240v dryer outlet.

NO difference. The charge current is still showing 8/8A.

This would seem to point to the outlet, which is a Leviton 14-50 (to match up with the Tesla Mobile Charger cable dongle (the only one supplied for 240v application). Everything seems to accept the setup, but it just doesn't deliver enough Amps to get the job done.

Yeah, a wall charger would be nice to have, but I've already spent over $250 on this, and paying an electrician $6-700 for a wiring job and Tesla about the same for the wall charger is a bit more than my budget can handle. Others have made this work, so I'm scratching my head figuring out why mine won't!

This still sounds to me like you changed your dryer outlet from its normal 14-30 outlet to a 14-50, which would mean that you have a 14-50 outlet wired to actual wiring that cant support that charging speed, and are thus depending on the breaker to save you if it overheats, or depending on being able to set the car speed lower in the car interface.

Neither of those things should be done.

You could have left the 14-30 outlet, and simply bought a 14-30 adapter for the mobile connector, and unplugged the outlet manually if you needed to use the dryer. It would have cost you about $50 from Tesla itself and would not have required changing outlets, etc:

Gen 2 NEMA Adapters

Use a variety of household outlets to charge your Tesla with a Gen 2 NEMA Adapter. Simply attach the appropriate adapter to your Mobile Connector, plug into the corresponding outlet and begin charging. Adapter Max Distance Gained Per Hour of Charge Model S Model 3 Model X Model Y 5-15 3...

shop.tesla.com

Since it sounds like you changed the outlet yourself, If you are bound and determined to use this setup, you should start by looking at your wiring of the outlet. Still, You should not (should not) be using a 14-50 outlet on wiring that is specced for a 14-30 connection. "you can burn your house down" is not just some random thing online. Turning the amps down in the car doesnt always "stick" and using the wrong outlet and adapter signal to the car the outlet is capable of more than it is.

People dont think their christmas trees are going to light on fire or that when they deep fry their turkey but arent sure if it fully defrosted, "it would be fine".

In any case, start with the outlet you wired, or consider returning that $250 worth of stuff, putting the 14-30 outlet back on there, and getting the $45-$50 14-30 adapter direct from Tesla for the mobile connector. No one is saying that you need a wall connector to make this work.

 

[E90alex]

What happens on a 120V outlet? Can you test it on a known good 14-50 outlet?

 

[brkaus]

It sounds like the mobile evse or the adapter. If you set the current at that location to be as low as possible, and then plugin, what does it do?

To me, since it says 8/8 it thinks 8 is the max. Do either the adapter is simply wrong or is dropping to 8 after detecting a problem.

You have the 5-15 adapter (regular outlet)? What does that do?

Not a fan of your setup, but that’s been addressed above.

 

[ucmndd]

Wow, this charging setup is like a 7 layer burrito of dumb. Don't forget the guac!

That said, first thing I'd do is try the UMC with the regular 120v 5-15 adapter then work backwards from there ruling out each layer in your burrito.

 

[MikeRTX]

To clarify what I have, I bought a dryer extension cord, NEMA 14-30 both ends. I then cut off the outlet end and wired the 4 leads to the NEMA 14-50 outlet. By all accounts, that should be fine and dandy, since the outlet would be throttled to 24A (if I could!) and the 14-50 outlet is then actually being underutilized (working below its rated capacity).

That leaves the dryer extension cord (rated for use on a 30A circuit) as being undersized EXCEPT that it was to be used at only 24A.

 

[DuncanM]

To clarify what I have, I bought a dryer extension cord, NEMA 14-30 both ends. I then cut off the outlet end and wired the 4 leads to the NEMA 14-50 outlet. By all accounts, that should be fine and dandy, since the outlet would be throttled to 24A (if I could!) and the 14-50 outlet is then actually being underutilized (working below its rated capacity).

That leaves the dryer extension cord (rated for use on a 30A circuit) as being undersized EXCEPT that it was to be used at only 24A.

It would be better to use a NEMA 14-30 adapter for the TMC and use the NEMA 14-30 plug since the TMC would then be set to use 24A max.

 

[E90alex]

While yes what you’ve done works in theory, it’s not to code. And you and everyone else in you household must always manually check and be 100% sure the charger and dryer are never used at the same time.

The main problem is with the 14-50 adapter on the UMC, the car doesn’t know it’s only attached to a 30 amp circuit.

Yes, you can dial down the amperage in the car manually but it’s not considered a fail safe solution because it’s only a software limit which can be changed by accident or be reset due to software updates or bugs.

If you had purchased the 14-30 adapter for the UMC, it has a chip that tells the car to never draw more than 24 amps and you can never increase it beyond 24 amps intentionally or accidentally.

 

[ucmndd]

To clarify what I have, I bought a dryer extension cord, NEMA 14-30 both ends. I then cut off the outlet end and wired the 4 leads to the NEMA 14-50 outlet.

That's an awful lot of hackery to avoid buying the $35 14-30 adapter for your UMC.

By all accounts, that should be fine and dandy, since the outlet would be throttled to 24A (if I could!)

Be prepared for your car to randomly forget this setting. In my experience it happens semi-regularly.

and the 14-50 outlet is then actually being underutilized (working below its rated capacity).

Until some knob comes along and plugs in their welder or something. 14-50 outlets don't belong on 30 amp circuits. Ever.