Hello, I am not saying you couldn't be correct, I'm saying it's not been an issue in 6 years of ownership. I'm pretty familiar with the UMC1, 2, etc, as well as the onboard charger. (I miss the days of the UMC1 and 40 amps). Anyway, (even though all this troubleshooting should never have to be done by the consumer).
History: Same NEMA 14-50 since 2015, when I had my first Model S on a UCM1 happily pulling 40 amps all day every day.
Wife's 3 is also plugged into a NEMA 14-50 from the same panel. (Different outlet, different breaker).
Not aware of any issues of it lowering to 31 amps now or ever.
My X has
always charged 32/32 day 1 (July 2019) until the firmware and iOS app let you change the amps.
The only thing that changed here is the feature I didn't ask for.
I always thought it would be neat to be able to do, but in 7+ years (Holy cow, has it really been that long?) of owning 3 Teslas... never actually
needed. The amps are set by the chip in the dongle telling the UMC to tell the car max amps.
I'm aware that if the voltage dips as the amps climb while it loads the the circuit, or while charging the car will reduce the amps to reduce the likely-hood of a problem/fire. Also aware of the temp sensors that do similar.
32 amps across a 50 amp breaker/outlet is no sweat. Car was charging just now at 32/32 at 245v. The on board charger in fact, can handle 11.5kw and 32 amps at 245 is only 7,840 watts.
I know (at 245v) I'm talking about 245 watts here... but dammit, 32 amps is already slower than I'd like. I shouldn't have to give up 1 more... especially when the onboard charger can handle it anyway.
I don't know what's worse. that it's occurring, or that you have to quadruple prove the sky is blue to service... I know it's a firmware issue, but if people don't report it... how would it get fixed? The pushed an update which now made my XM all but useless... ugh. can't win.
Anyway, I used to run Visible Tesla on my first S, it logged amps/volts nicely. I don't know if that's still around or not. I also have a Sense which can show me down to the second I think of voltage history.
While I've been typing this, I set the amps to 32 (as it was at 31). Now I just checked the app in the time it took to write this... shows.... wait for it... 31! lol
**screen shot shows 246v. It must have changed to 245 quickly after so the math above is on the 245 figure.
point is, it runs 32 amp at 246 just fine.
I know y'all are trying to help, but really it's gotta be a firmware issue, they take 2 steps forward and 1 back so often with this stuff...
Tesla Service says it's not throwing any charging errors. Which means go away.