Apologies in advance to the sensitive souls if there's already a thread on this issue! I have 2018 (Aug-Sep build) M3 LR AWD. I had a Tesla wall charger installed when I purchased the car. Connected to a 60 amp breaker, it output 48 amps and I enjoyed a charge rate of about 44 miles per hour. A couple days ago I noticed that the charge rate had dropped below 30 miles per hour. I tried to charge the car at a Tesla super charger and (was the lone person there) and only drew 39 amps. I've attached a picture of my screen (charging at home with the Tesla wall charger) - if you look closely on the LHS, there's a notification about a reduced charge rate. My guess is that the issue is with the car and not the charger - could someone substantiate this? Has anyone else had this issue and if so how was it resolved? Thanks in advance.
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Degraded Charge Rate
- Thread starter khoon
- Start date
I'd try one more thing, but if you're being limited only to 32A it'd be hard to check.
Try a public station with the J1772 adapter (but it need to be one >30A, which is rare). See if the behaviour occurs there as well.
When you pulled up to the Supercharger, what state of charge were you at and how were the temps? Pulling only 39A could be entirely normal depending on those two figures. It could have also been a wonky Supercharger unfortunately.
For others here, the onboard charger (can't remember the correct term for it) has been faulty and thrown these types of messages, surprisingly not indicating that anything is truly faulty. Best bet will probably be to set up a service appointment. Historically I think it's also been a charge port issue, again requiring service. No simple DIY solution except making sure it's plugged in firmly.
Try a public station with the J1772 adapter (but it need to be one >30A, which is rare). See if the behaviour occurs there as well.
When you pulled up to the Supercharger, what state of charge were you at and how were the temps? Pulling only 39A could be entirely normal depending on those two figures. It could have also been a wonky Supercharger unfortunately.
For others here, the onboard charger (can't remember the correct term for it) has been faulty and thrown these types of messages, surprisingly not indicating that anything is truly faulty. Best bet will probably be to set up a service appointment. Historically I think it's also been a charge port issue, again requiring service. No simple DIY solution except making sure it's plugged in firmly.
This symptom of only being able to use 32A out of 48A is something I've seen on this forum a few times before, and it's usually a defective internal charger. They use multiple modules inside the internal charger, and they are capable of handling 16A each. So the smaller battery cars have two of those for 32A total, and the larger battery cars have all three of them, for 48A. With the way the cars will drop back to 32A if one of the modules goes out, is a nice form of "failing gracefully", as they say in tech industry terms.
Thanks for your replies. I did notice that the Charge screen on my car indicated 32/48. I take that to mean that it was receiving 48amps but only charging at 32 amps, the culprit most likely being the car's power management system. I had make a service appointment and yesterday they changed it from home service to Tesla's local service center - they said it was based on their review of diagnostics. I will keep this forum updated on developments.
Slight correction on the terminology. It can't be "receiving" 48A if it's not using part of it. The 48A is the amount that the external charging unit is announcing and that the car is seeing as available. But 32A is the amount that the car is actually requesting and receiving at the moment. That could sometimes show that you might be able to manually dial that up, but if you can't then yes, the internal charger is probably limiting it for some reason.
eprosenx
Active Member
Looking at the image that he posted, it appears the car is set to charge at 48 amps but it is only effectively charging at 32 amps even though it says 48 amps are available.
If it was a failed / unlatched charge port the speed would be limited to 16 amps.
This is going to be a defective charger module as mentioned above. One of the three 16 amp lineups is failed. They will replace the entire charger as it is one unit.
AhwatukeeDad
Member
Supercharging bypasses the charger but it doesn’t bypass the charge port...
The 48A to 32A certainly in one of the AC charging modules but make sure to tell the SC about the reduced supercharger capability.
How empty was the battery when at the supercharger? If close to full 39 miles and hour might be right? No seems too low.
good luck!
The 48A to 32A certainly in one of the AC charging modules but make sure to tell the SC about the reduced supercharger capability.
How empty was the battery when at the supercharger? If close to full 39 miles and hour might be right? No seems too low.
good luck!
Are you sure it wasn't a destination charger you visited instead? I don't get to see amps when supercharging, just +kW/+mph.
I forgot to address that, but I'm pretty sure that's user error. I see tons of people not pay attention to the units on the screen and assume when they are stating it here on the forum. Charging at home uses amps, so I'm thinking the person didn't pay attention to the fact that the units shown when at a Supercharger are different and just glanced at it and thought it was amps too. That was probably 39 kilowatts, which could be a pretty normal charging power level for a more than half full battery.
AhwatukeeDad
Member
Well, that wouldn't explain that. The urban ones are only capped on the very top end maximum power, which is I think 72 or 75kW. They are not lower power across the board. So if this is showing 39kW, that's limited by the car. It's not nearly at the top end limit of an urban style Supercharger.
In fact, that would be far less likely to be the case, because the urban ones always do an even half and half split of the pair of stalls, so there they don't have that uneven split, where the "Primary" first car gets most of the power, and the "Secondary" car gets less.
So I just noticed this tonight on my HPWC; any idea what would cause this? If it were 32/48 amps, I'd think one of the 3 modules in the onboard charger were having an issue. But since it's 34 of 48, any ideas?
Haven't tried any other HPWC's or destination chargers (or even a mobile charger) but ... this seems odd.
Haven't tried any other HPWC's or destination chargers (or even a mobile charger) but ... this seems odd.
swaltner
Active Member
What is the Voltage reading on that circuit before it starts charging? (when it says 0/48 Amps) If there is enough voltage sag, the Tesla could be backing off on the charge rate. Your 237 Volts doesn't seem too bad, so I doubt it's an issue with voltage sag.
Generally, when the charge rate drops, there's some form of alert on the dash as to why.
Generally, when the charge rate drops, there's some form of alert on the dash as to why.
Starts at 239V pretty consistently. 2-3V either way shouldn’t really affect much.
No alerts on the dash - it didn’t start at 48A and drop; it just ramped up to 34A and stopped.
Unusual.
I'm a bit confused as to the OP's original post. First for whatever reason I can't see the second image (a pdf) so not sure what that's about. I noticed the following on the image that was visible.
The screen above that was provided is of a home charging set up since it says Charging and not Supercharging. The charging that previously occurred at the Nyack, NY Supercharger location, which is not an urban charger, gets up to 150kW btw. Not sure if this was the same Supercharger he expressed issues with or not.
Hard to say how long after charging had started at home that the photo was taken. Guessing not long. I would normally expect tapering since the car is already more than 50% charged. He's only added like 1 mile of range so the car would be adjusting as it starts up. But then there's the Alert.
OP did you unplug the car and replug it in as per the Alert? Maybe it's a problem with your pin connectors in the charge port. My AWD Model 3 a 9/18 build, just had service done by mobile for AC filters and condensor cleaning, and one of the Basic Limited Warranty items they performed was a replacement of my Charge Port Insulator Pins with updated parts. There was a bulletin on this. I had not had any problems with my car but it was done proactively and the tech said it was something they had seen with older Model 3s so they were just replacing them as they came in for service. Wondering if this area on your car could have been an issue and gave you the Charge Rate Reduced alert and suggestion on unplugging and replugging.
Apart from also bringing out my AWD badging (got delivery before there was sufficient supply of and didn't do the group badging when it became available) and checking the tire pressure (CA Mandate for all service appointments), they also had a bulletin to re-adjust the frunk hood latch. Mine was fine but it was something else some people experienced problems with on the early cars.
OP I see you had your mobile appointment rescheduled to a SvC. Will be interested to see what they determine the issue is with yours.
The screen above that was provided is of a home charging set up since it says Charging and not Supercharging. The charging that previously occurred at the Nyack, NY Supercharger location, which is not an urban charger, gets up to 150kW btw. Not sure if this was the same Supercharger he expressed issues with or not.
Hard to say how long after charging had started at home that the photo was taken. Guessing not long. I would normally expect tapering since the car is already more than 50% charged. He's only added like 1 mile of range so the car would be adjusting as it starts up. But then there's the Alert.
OP did you unplug the car and replug it in as per the Alert? Maybe it's a problem with your pin connectors in the charge port. My AWD Model 3 a 9/18 build, just had service done by mobile for AC filters and condensor cleaning, and one of the Basic Limited Warranty items they performed was a replacement of my Charge Port Insulator Pins with updated parts. There was a bulletin on this. I had not had any problems with my car but it was done proactively and the tech said it was something they had seen with older Model 3s so they were just replacing them as they came in for service. Wondering if this area on your car could have been an issue and gave you the Charge Rate Reduced alert and suggestion on unplugging and replugging.
Apart from also bringing out my AWD badging (got delivery before there was sufficient supply of and didn't do the group badging when it became available) and checking the tire pressure (CA Mandate for all service appointments), they also had a bulletin to re-adjust the frunk hood latch. Mine was fine but it was something else some people experienced problems with on the early cars.
OP I see you had your mobile appointment rescheduled to a SvC. Will be interested to see what they determine the issue is with yours.
smatthew
Active Member
You ever figure this out? Noticed mine did the same exact thing last night, went to 34/48 amps and stayed there and was at 238volts.
Unfortunately; no. It self-resolved the next day - back to the usual 48a, and hasn’t done it since. Someone “who would know” logged in and checked the car for me - Nothing unusual. Just a one-night glitch.
All fine now!
