Home charging

[ATPMSD]

I'll see what I can do. But as I've stated. My voltmeter reading 240 coming out of 15ft extension, as well as the 14-50 adapter, and display in car shows 237 volts

Voltage under load is what counts, perhaps re-read Beatle's post. My suggestion for a trip to the RV park is to rule out issues with the mobile connector.

 

[Rocky_H]

How do you distinguish gen 1 and gen 2 Tesla Mobile connectors?

You can look in the Tesla store and see the adapters for the Gen1 versus the Gen2. They look very different. They stopped including the Gen1 version with the cars about 2018-2019 or so, so unless you bought a noticeably older used car, you have Gen2.

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

My guess is that your voltage is dropping at some point and the charger will then cut the amps. I did this on a 14-50 installed in my father's garage using a first gen UMC. It started at 40A 230V and then slowly dropped to 223V. At that point the charger dropped to 30A and continued to charge, bringing the voltage back up over 230V.

Unplug the UMC and then plug it back in. Then connect to the car and check the amps. If it reads 32A, continue to monitor and see if it drops to 24A. In my experience it took about 20 minutes before the charger gave up on the voltage droop and lowered the amps, but that may vary depending on the voltage drop.

I have also charged on an extension cord (12awg to 6-20 receptacle) and had no issues or droop, so extension cords aren't inherently evil.

Yes, I am going to agree that it's probably this for two reasons:
Extension cord puts some extra resistance in there, so more likely to have extra voltage drop there.
And the 24A is the symptom of that. The car checks the voltage at first, before charging, and then after it ramps up the current, and if it sees too much difference, it will lower to three fourths of the current it was trying to use. 24 out of 32 would be it.

So first off, maybe check the wire connections in the back of your outlet to make sure it doesn't have anything loose, which could be causing resistance. That would be bad. But overall, as long as that's tight, using a 15 foot extension cord shouldn't be too big a deal, but is a little extra resistance. So what you could try is when you first have it start charging, have the amps down low, and slowly turn it up. You may find that it can do 26 or 27 amps without getting up to that level where the car sees the voltage drop as being too much and kicks in that safety feature to reduce it.

 

[beatle]

But overall, as long as that's tight, using a 15 foot extension cord shouldn't be too big a deal, but is a little extra resistance.

Indeed, as a data point on voltage, when I used my 6-20 extension cord, the average voltage was 241v. Without it, I get 243v. It's not much, but it's something. My extension cord is 12awg and about 25 feet long.

I think the car is happy to charge at a lower voltage as 208v is okay at commercial buildings and some public chargers, but the car doesn't like seeing the voltage drop.

 

[BigNick]

Indeed, as a data point on voltage, when I used my 6-20 extension cord, the average voltage was 241v. Without it, I get 243v. It's not much, but it's something. My extension cord is 12awg and about 25 feet long.

I think the car is happy to charge at a lower voltage as 208v is okay at commercial buildings and some public chargers, but the car doesn't like seeing the voltage drop.

208V is fine if it's stable. If it drops below 200V or so, at L2 public chargers that normally support 30A, I get dropped to 22A to 24A (this would occur on my previous Tesla as well as my current one.)

 

[cduzz]

It would be really nice if the car explained why it is doing this.

I think there are several safety measures in the charging process.

One is "let's look at the voltage available with no load, a little load, and full load; if there's a lot of drop, reduce the charge load / amperage until there's an acceptable drop."

Another is "What's the temperature of my plug and the plug into the car? If the temperature is too high reduce the charge load / amperage."

You can sit in the car / look at your phone to see the voltage drop as it ramps up charging.

Do you need to charge at the full rate? (Answer yes if you get home with a mostly empty battery after leaving with a mostly full battery, or if electricity is substantially cheaper in a short window of time, usually overnight).

I've found I can get by just fine with 10a/240v. I've got 16a/240v available to me but found that the charger plug (into the house) heats up to a concerning degree. (I'm going to be swapping my current rig for a mobile charger / nema 6-20 setup because of this).

 

[CaliSurfer]

What is your circuit breaker rated at? If it's not rated for 40 or 50 amps, I don't think you'll see anything higher than you are.