Help with 14-50 outlet charging.

[Starpower4U]

I'm puzzled, I just installed a 14-50 outlet onto my off-grid system. I only had 120V so I purchased a 120-240V industrial GE 5kW transformer (My system can only supply 3.6kW) I plan to limit the charge rate to 3kW max with 2.5kW typical. The transformer does not have a neutral tap but my understanding is that the UMC gen. 2 does not require one, is this correct? I can charge fine at home with this UMC at 120V and fine on my daughters 14-50, 50A. But at home on 240V I can only get a 2 red blinks on the UMC indicating a grounding issue and no charge. I've triple confirmed proper grounding (retired electrician) and it is on the same ground as the 120V outlet, I even added it's own dedicated ground wire. In addition the feeding panel is in my metal building shop and bonded the the frame as well. The transformer is also grounded and mounted to the same metal building. I do get 240V at the new 14-50.

I suspect the the 2 red blinks in my case does not mean a ground issue, but what? Tesla charging support can only say it is a grounding issue.

Any thoughts?

 

[jjrandorin]

Any thoughts?

That I am not sure at all why you are trying to use a 14-50 outlet when you say the max amount of power you have available is 3.6kW. The outlet type tells the mobile connector what it can draw, and you should never (ever) be "depending" on turning down the amps in the car to set a proper charge speed on a Tesla, since its possible for an update to change that logic.

Since you only have 3.6kW of power available, it seems to me that you should be using a 20amp outlet (and breaker), like the Tesla 6-20:

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

 

[E90alex]

My guess is the UMC doesn’t like the stepped up voltage from your transformer for whatever reason.

If you only have 120V supply it might be better to install a 120V 30amp TT-30 outlet which will give you up to 2.8kW of charging. EVSEadapters sells a TT-30 adapter for the UMC.

 

[Watts_Up]

I'm puzzled, I just installed a 14-50 outlet onto my off-grid system.
I only had 120V so I purchased a 120-240V industrial GE 5kW transformer (My system can only supply 3.6kW)

Can you describe your off-grid system?

Do you get solar energy and use an All-In-One 120V AC inverter?
Do you have any Batteries? If so, what volatge and Ampacity?



Note: If you have an All-In-One inverter and 48V batteries, the correct way to get 240V with neutral
is to use a separate 48V DC / 240V AC inverter with Neutral (not an European 220V inverter) connected directly to your battery.

Another approach would be to have two identical All-In-One 120V AC inverters connected in phase.


In the case of a separate 48V DC / 240V AC inverter:
- you should turn on this inverter only when your batteries are charged
and when you have surplus of solar energy otherwise you will quickly discharge your batteries.
- you should also turn off this inverter when you are not charging your car, for better efficiency of your off-grid system.

 

[Starpower4U]

My guess is the UMC doesn’t like the stepped up voltage from your transformer for whatever reason.

If you only have 120V supply it might be better to install a 120V 30amp TT-30 outlet which will give you up to 2.8kW of charging. EVSEadapters sells a TT-30 adapter for the UMC.

Big thanks E90alex!! This is an excellent option and I just ordered it. wish I was aware of this before I purchased this $300 transformer!