Something limiting power from Mobile Charging Cable

[EdL-ATX]

I have a NEMA 14-50 outlet with a 60A breaker. Recently when using the Lucid Mobile Charging Cable (that comes with the car), I’ve seen the power limited to 5kW during charging. I (believe I) was seeing the expected 9+KW the first time I used it but recent times it always stays at 5kW. I plugged our Tesla mobile charger in to the same outlet and when connected to our Model S it gets the expected ~7.6kW, so doesn’t seem to be an issue with the outlet. FWIW I generally leave the Lucid cable plugged into this outlet.

Has anyone seen this? Does the car throttle charging power for any reason that I should be looking for?

 

[Adnillien]

I have always seen 9kW when using the Lucid mobile charging cable and I have not seen it slow down. I also have not charged to 100% where it may start to slow down. Were you at a high SOC when you saw this?

 

[LCIDdreams]

My understanding is that an overrated breaker (in this case a 60A breaker for a 50A outlet) is a no-no: it’s against code and increases risk of fire.

May have nothing to do with your charge rate issue though.

 

[borski]

My understanding is that an overrated breaker (in this case a 60A breaker for a 50A outlet) is a no-no: it’s against code and increases risk of fire.

May have nothing to do with your charge rate issue though.

Correct; those outlets are only rated for 50A and need to be on a 50A breaker. If you want 60A you have to hardwire.

 

[FastEddi3]

My understanding is that an overrated breaker (in this case a 60A breaker for a 50A outlet) is a no-no: it’s against code and increases risk of fire.

May have nothing to do with your charge rate issue though.

That is correct on both items. The 50 in the 14-50 is the max amps, so should be a 50 amp breaker. It may have been originally wired as a 60 amp circuit with 6G wire, which would have been okay if things are hardwired into that circuit, but once a 14-50 outlet is wired into it, the 60amp breaker should have been changed to a 50amp breaker, since the 50amp outlet is now the limiting factor. That is out of code, so if your electrician did that, they should come back and fix it. Or you can hardwire a level 2 charger like a Juicebox, Chargepoint, or whatever. Then you could charge at 48amps.

But that should not have anything to do with the max charge rate. That should still be 40amps (which is the standard draw rate on a 50 amp circuit, allows for 125% surge amperage and still stay within safe current flow) x 240v, which equals 9.6kW.

If the Tesla is charging at 7.6kW, which I think is the max rate on the Tesla charging cable (I believe it's a 32A charger) then there is some sort of issue with the Lucid charging cable. For some reason, the charging cable thinks that it can only safely charge at 20A. (20A x 240v = 4.8kW). Is the Lucid charging cable plugging all the way in? Is there any sort of junk or corrosion on the connectors? (The charging cable tests itself, then tells the car what it is allowed to charge at.)

 

[EdL-ATX]

Acknowledged on the 60A breaker the electrician installed. Will update.

But agree there must be some other limiter since I would be surprised if that is what is causing the Lucid cable to think it can charge at ~20A.

Will double-check the connections including the adaptor plugged into the Lucid brick, etc. Thanks for the ideas.

 

[EdL-ATX]

I have always seen 9kW when using the Lucid mobile charging cable and I have not seen it slow down. I also have not charged to 100% where it may start to slow down. Were you at a high SOC when you saw this?

Oh...and it was maybe ~65% SOC when I was seeing this. Stayed that way consistently up to the 80% limit I had set. So shouldn't have been anything like getting close to the limit (like was showing hours of charging remaining). I will try running the battery down lower among other experiments to see if any difference.

 

[Adnillien]

Oh...and it was maybe ~65% SOC when I was seeing this. Stayed that way consistently up to the 80% limit I had set. So shouldn't have been anything like getting close to the limit (like was showing hours of charging remaining). I will try running the battery down lower among other experiments to see if any difference.

The car will not start limiting level 2 charging current until very near 100% SOC. I have charged to 95% and it was still showing 9kW. Something is odd. If you have a time stamp, send it to customer care and let them look into it.

 

[EdL-ATX]

Thanks. Will do. They're sending someone out later this week. He'll also bring another charging cable so we can test that out. Will update the thread with any findings.

 

[EdL-ATX]

Mobile service came out today. Thankfully the problem ended up being the 14-50 connector of all things. They replaced my entire mobile charger since they don't have just that connector by itself, apparently. So now getting 9kW from the charger. Happy day.

As an aside, my overall experience with calling customer care and with the local mobile service here in ATX was really positive. Can't really complain.