Home charging very very very slow

[Yaozers]

I’ve had my model S since 2016, with a home charger. It has worked normally until about a week ago. Now it looks like it charges at 0 to 1 mile per hour. There’s no odd indications. The wall unit still has the green like before, and my car charges without a problem at super chargers. I turned off the fuse box and back on, that didn’t help. The car and the app both show 1/46A, which can’t be good.

Anyone have any ideas on what I should look into to identify the problem?

 

[EVFamilyGrins]

Sounds like issue could be with either with your charger or the cars on-board charger that converts AC to DC. I would try charging a public level 2 charger and see if it acts the same or try using your UMC at home from an outlet and see if you get the 3ish miles expected from an outlet.

 

[Yaozers]

Sounds like issue could be with either with your charger or the cars on-board charger that converts AC to DC. I would try charging a public level 2 charger and see if it acts the same or try using your UMC at home from an outlet and see if you get the 3ish miles expected from an outlet.

By “public level 2 charger”, do you mean something similar to what I have at home but not a super charger? (Sorry, I am not tech or car savvy).

 

[father_of_6]

Yes. The idea is to isolate the issue. At this time, we don't know if the issue is with your car or your charger... so the first step in troubleshooting is to try your car with someone else's similar (L2) charger, or vice-versa... try someone else's car with your L2 charger.

That should tell you if it's the car or the charger (EVSE technically... the charger is actually built into the car).

 

[father_of_6]

I could be wrong, but I *suspect* that if the issue was in the car (e.g. failed PCS module), then the car would be reporting a problem.

Also... 46A seems strange to me. Has it always been 46A? Since EV charging represents a "continuous load" (more than 3 hours of draw), the amperage must be at *MOST* 80% of the circuit breaker. 46 AMPS implies a 57.5 AMP breaker, which we all know doesn't exist. Usually an L2 charger would be 40A for a 50A breaker or 48A for a 60A breaker.

 

[Yaozers]

Very good. Makes sense. Thanks for the advice

 

[Yaozers]

I could be wrong, but I *suspect* that if the issue was in the car (e.g. failed PCS module), then the car would be reporting a problem.

Also... 46A seems strange to me. Has it always been 46A? Since EV charging represents a "continuous load" (more than 3 hours of draw), the amperage must be at *MOST* 80% of the circuit breaker. 46 AMPS implies a 57.5 AMP breaker, which we all know doesn't exist. Usually an L2 charger would be 40A for a 50A breaker or 48A for a 60A breaker.

Honestly I don’t know. I just know when I plug it in at home, it’s always charged to my limit the next morning, regardless of what time I get back. Not a great help with numbers, but when it worked, I never asked or was curious enough to find out.

 

[Yaozers]

Well, I used the long cables and plugged it into my home outlet. Initially the car looked like it would charge at 12A, 4mi/hr, but after a half hour, nothing, and it was fluttering between 1/12A and 2/12A

 

[ATPMSD]

You really need to isolate the problem. Take your car to a public EVSE (Electric Vehicle Supply Equipment) like ChargePoint and see what happens. In the car you should see something like 24/24 or 32/32, this will depend on the available current of the station. If you see such numbers then the problem is with your wall connector. If you still see a problem when using the public EVSE the problem in within the car.

I agree with @father_of_6, 46A is very odd. Could be a voltage problem in your home.

BTW, do not use extension cords!

 

[EVFamilyGrins]

Well, I used the long cables and plugged it into my home outlet. Initially the car looked like it would charge at 12A, 4mi/hr, but after a half hour, nothing, and it was fluttering between 1/12A and 2/12A

Based on this comment, when you plug into outlet (not using extension cord) or wall charger, do the amps ramp up towards 12/12A or 48A and then drop back to 1/12A. If so, this seems to imply that the car is requesting normal power and then scaling back as it can't handle it.

Problem is most likely with the cars PCS (Power Conversion System) and I would open a service ticket.

Good Luck and please let us know how it turns out.

 

[Yaozers]

Based on this comment, when you plug into outlet (not using extension cord) or wall charger, do the amps ramp up towards 12/12A or 48A and then drop back to 1/12A. If so, this seems to imply that the car is requesting normal power and then scaling back as it can't handle it.

Problem is most likely with the cars PCS (Power Conversion System) and I would open a service ticket.

Good Luck and please let us know how it turns out.

Yes. This is what’s happening. Thanks

 

[Yaozers]

To finish up this thread: Tesla said it was the on board charger failing, exactly like you guys said was likely. Replacement was $2200. Labor and diagnostic another $600

 

[ucmndd]

I agree with @father_of_6, 46A is very odd. Could be a voltage problem in your home.

My car does this when the mains voltage is higher than nominal. OP’s car is reporting 251v, a good bit higher than the typical 240v.

That’s not really a problem, but in my experience the car backs off the amperage to stay within the “11.5kw” spec of the onboard charger.