Home charging now stepping down to 24 amps during the charging session

[bedoig]

I have a NEMA 1450 outlet on a 50 am breaker. I regularly have 32 amps charging @ 29 miles per hour. It's been the same since I first installed it at my old house and is that way now at my new place. Occasionally, the charge starts slowly but then it builds and levels off consistently at 29 mph and 32 amps.

The current UMC maxes at 32 amps, so that's normal. Gen 1 did 40. For anything else you need a HPWC or other J1772 unit.

 

[Gasaraki]

I'm bumping this thread because i'm experiencing a similar issue with my WC with 14-50 plug that I purchased 9/2019. I have a 50a breaker, and would consistently get 40a allowing me to charge 37mi/hr/9.6kW.

But in the last few months, I noticed that it would start from 40a for the first 10 minutes or so then drop to 30 amp, and in some cases even below that. Just now, I tried sitting in my car to wait for this to happen so I can take a screenshot of the error message. So it started at 40a as expected, charging the car at 9-10kW for the first 10 minutes or so, then it dropped to 30a on the car. But, I never got an error message.

Does anyone know why i'm not getting an error message?

It's raining out in my area, so I'll wait until the break from rain to open up the WC so I can take a look at the wires.

There are no error message that you can see. However if you call Tesla, like i did, they can pull logs from the gen 3 wall connector and see what is causing the wall connector to ramp down charging amperage to the car.

 

[P-Lo801]

I have a NEMA 1450 outlet on a 50 am breaker. I regularly have 32 amps charging @ 29 miles per hour. It's been the same since I first installed it at my old house and is that way now at my new place. Occasionally, the charge starts slowly but then it builds and levels off consistently at 29 mph and 32 amps.

Yeah mine is the HPWC with 14-50 plug. It's no longer sold by Tesla.

 

[P-Lo801]

There are no error message that you can see. However if you call Tesla, like i did, they can pull logs from the gen 3 wall connector and see what is causing the wall connector to ramp down charging amperage to the car.

My HPWC isn't gen 3 unfortunately. So how else can I troubleshoot this for error codes?

 

[Gasaraki]

My HPWC isn't gen 3 unfortunately. So how else can I troubleshoot this for error codes?

If it's the Gen2, the issue is most likely the 14-50 socket. I would get that checked out quick. Other posts have had the socket melt and almost start fires. The wall connector is lowering the amperage due to heat to protect you.

 

[P-Lo801]

If it's the Gen2, the issue is most likely the 14-50 socket. I would get that checked out quick. Other posts have had the socket melt and almost start fires. The wall connector is lowering the amperage due to heat to protect you.

Thanks. Could you give me some pointers as to the posts you're referring to?

 

[Gasaraki]

Thanks. Could you give me some pointers as to the posts you're referring to?

Yep, let me find it for you. Totally forgot yesterday.

EDIT:

Here is one:
NEMA 14-50 Plug Meltdown / Near Fire

 

[P-Lo801]

Yep, let me find it for you. Totally forgot yesterday.

EDIT:

Here is one:
NEMA 14-50 Plug Meltdown / Near Fire

Thanks for finding this. I've only skimmed through it, but this appears to be an issue mostly with the UMC gen1. I have the HPWC with 14-50.

 

[Gasaraki]

Thanks for finding this. I've only skimmed through it, but this appears to be an issue mostly with the UMC gen1. I have the HPWC with 14-50.

The issue is not with the wall connectors, so it doesn't matter if it's gen 1 or 2. Gen 1 will just allow it to go full bore even when the temp is high. Gen 2 will ramp down amperage. So just check the socket, that all I'm saying.

 

[P-Lo801]

The issue is not with the wall connectors, so it doesn't matter if it's gen 1 or 2. Gen 1 will just allow it to go full bore even when the temp is high. Gen 2 will ramp down amperage. So just check the socket, that all I'm saying.

Ah got it. Alright, thanks again.

 

[STDRDC13]

My 2016 Model S (refreshed) now will only take AC at 23A no matter what Level II charger I use. Had a friend plug into my Wall Connector and their Model Y pulled down 48 amps, just as mine has done for the past 6 yrs on the 60amp circuit wired with 6 gauge copper. My MS has the duel 24amp AC/DC inverters and I feel one has failed resulting in the half rate charging.

Any others having the same issue?

 

[dbldwn02]

My 2016 Model S (refreshed) now will only take AC at 23A no matter what Level II charger I use. Had a friend plug into my Wall Connector and their Model Y pulled down 48 amps, just as mine has done for the past 6 yrs on the 60amp circuit wired with 6 gauge copper. My MS has the duel 24amp AC/DC inverters and I feel one has failed resulting in the half rate charging.

Any others having the same issue?

Yea, I did last year. V3 charger. Single 48amp charger. I'd be willing to bet you have the same setup I do.

If you have the V2 charger, though, it could be your 50amp fuse.

Here's my write up on replacing the onboard charger yourself and saving $3000USD.

Replacing Onboard Charger Gen3 2017 MS75D...My Experience (With Photos)

Here is my experience replacing my onboard charger on my 2017 Tesla MS75D. Disclosure… Don’t try this at home, YMMV, High voltage, you can kill yourself if you do something stupid, yadda-yadda, I’m not liable if you do this, warranty void, blah blah blah… My car specs: 2017 MS 75D (USA) Gen...

teslamotorsclub.com

 

[gbcomp]

I think it's the wall charger or electrical feed as well. What's perplexing to me is that it starts out at 48a and then eventually (after at least 20 minutes in both my cases tested), it drops down. And if I restart, it immediately goes back to 48a.

I have the same issue I even had a red light show up on my wall charger at the dame time the green flow leds were on while it was charging

 

[M3BlueGeorgia]

The issue is not with the wall connectors, so it doesn't matter if it's gen 1 or 2. Gen 1 will just allow it to go full bore even when the temp is high. Gen 2 will ramp down amperage. So just check the socket, that all I'm saying.

Probably the wiring in the wall feeding the 14-50 socket isn't thick enough to sustain 32A continuous.

The Gen 2 most likely detects a drop in voltage (which you can see displayed in the car) and then infers it is pulling too much amperage.