Can changing amperage while charging simply be heat related?

[robbyville]

Hi folks,

Recently (within the last few days), my charging, using a Tesla Wall charger, dedicated 60am circuit wired directly through the wall will start at 48amps but will later drop to 24amps. Sometimes it does this within a half hour, sometimes a few hours in. I charge every night and drive a fair bit (over 30,000 miles in year one).

I have done a little research here on the site, and have seen that this is often caused by messed up onboard chargers within the car, but I'm wondering if it could also just be heat related although this never happened last summer.

Couple things to note:

• It's incredibly hot where I live right now averaging 112 during the day
• Garage is probably at 95+
• I first noticed this when plugging in the car after a recent trip and when I got home. The car was quite low (11%) and I plugged it in right away so everything was very hot
• Car is about 16 months old, purchased new March 1 2022

Is there any way that I can see if it's a car issue and if it is would this be covered by warranty?

thanks for any guidance!

 

[Shelburne]

I've been charging my M3 at home using the Tesla mobile charger and a Nema 14-50 plug which I plug into a 240 volt line. Last summer and this summer I've noticed a drop in the rate of charge of about 50%. That doesn't happen in the winter, but it does happen when the ambient outdoor temperature is over 70 degrees. I have an electrician coming to look at the situation next week and will be back to report on what he finds

 

[robbyville]

I've been charging my M3 at home using the Tesla mobile charger and a Nema 14-50 plug which I plug into a 240 volt line. Last summer and this summer I've noticed a drop in the rate of charge of about 50%. That doesn't happen in the winter, but it does happen when the ambient outdoor temperature is over 70 degrees. I have an electrician coming to look at the situation next week and will be back to report on what he finds

That would be great thank you! My Tesla charger was installed by an electrician and I haven't had any challenges until now. To be fair though, all last summer we would have similar heat and I don't believe I had any challenges. Then again most of my charging is in the middle of the night, and this jsut started when I had to charge during the day and right after a drive. It seems to be happening at every charge right now, home charging at least, but yesterday I noticed that it stayed at 48 for at least a couple of hours before dropping to 24.

 

[robbyville]

Update, I just went to look at the car and charger since it's currently charging at 24amps. The app still looks normal with no error reports, same as the car display. However I did notice that the charger starts off with a red LED before turning green and going through the visual green line of led's to show charging. Pics attached

 

[Hebert]

Update, I just went to look at the car and charger since it's currently charging at 24amps. The app still looks normal with no error reports, same as the car display. However I did notice that the charger starts off with a red LED before turning green and going through the visual green line of led's to show charging. Pics attached

Seems like your problem could be in a couple of places. Lower charging amps can be a loose connector. It can be hard to get a tongue wrench on when tightening to make sure it's tight enough. The manual has a list of fault codes, i think 1 red indicates something to do with the ground but I'm not 100% sure.

 

[ewoodrick]

Hi folks,

Recently (within the last few days), my charging, using a Tesla Wall charger, dedicated 60am circuit wired directly through the wall will start at 48amps but will later drop to 24amps. Sometimes it does this within a half hour, sometimes a few hours in. I charge every night and drive a fair bit (over 30,000 miles in year one).

I have done a little research here on the site, and have seen that this is often caused by messed up onboard chargers within the car, but I'm wondering if it could also just be heat related although this never happened last summer.

Couple things to note:

• It's incredibly hot where I live right now averaging 112 during the day
• Garage is probably at 95+
• I first noticed this when plugging in the car after a recent trip and when I got home. The car was quite low (11%) and I plugged it in right away so everything was very hot
• Car is about 16 months old, purchased new March 1 2022

Is there any way that I can see if it's a car issue and if it is would this be covered by warranty?

thanks for any guidance!

When you are getting to the temps that you are, don't expect anything to work at full speed.
The car is possibly trying to cool the batteries down, that's going to use power and it will generate heat. If the garage feels too warm, it may be helpful to vent the garage door a little to let some of the heat out.

Before I do anything, I'd wait for the temps to drop a bit.

 

[robbyville]

Seems like your problem could be in a couple of places. Lower charging amps can be a loose connector. It can be hard to get a tongue wrench on when tightening to make sure it's tight enough. The manual has a list of fault codes, i think 1 red indicates something to do with the ground but I'm not 100% sure.

Hmm good call, I just downloaded both troubleshooting tips and the manual. I can't tell if this would count as 3 blinking red's or 1 blinking red lol. Seems to blink once and then do the green stream down. 3 blinking is heat related, says that it usually would be with ambient temps over 122 but that in some circumstances adjust with ambient temps over 95 (that's us). Also seems from the manual that if it was a ground (one blink red) that charging is then disabled, I assume that would mean completely?

I'm going to try the troubleshooting section and see if it gives me any info. I'm hoping that since I'm not getting any errors that it has nothing to do with the car...

 

[robbyville]

When you are getting to the temps that you are, don't expect anything to work at full speed.
The car is possibly trying to cool the batteries down, that's going to use power and it will generate heat. If the garage feels too warm, it may be helpful to vent the garage door a little to let some of the heat out.

Before I do anything, I'd wait for the temps to drop a bit.

Yeah you are probably right. Of course if I vent my garage right now I'd just be taking in 112 degree air lol! Strange though that this never happened (to my knowledge) last year.

 

[ewoodrick]

Yeah you are probably right. Of course if I vent my garage right now I'd just be taking in 112 degree air lol! Strange though that this never happened (to my knowledge) last year.

Neither did the "How many days above 110?" It's the night time that I was mostly referring to. If it does cool down a little in the evening and you can vent some of the heat, if nothing else that may decrease your home AC load.

 

[ucmndd]

This is a heat related problem and response.

Try charging at 32 or 40 amps to see what happens. Even with a lot of driving that’s plenty fast to get a complete charge overnight.

 

[robbyville]

This is a heat related problem and response.

Try charging at 32 or 40 amps to see what happens. Even with a lot of driving that’s plenty fast to get a complete charge overnight.

It won't let me change once charging at 24amp. Although I guess if I start the charge over again it starts at 48 and then I could manually lower it

 

[robbyville]

Neither did the "How many days above 110?" It's the night time that I was mostly referring to. If it does cool down a little in the evening and you can vent some of the heat, if nothing else that may decrease your home AC load.

Good point, will do. I never really vent or leave the garage partly open like some do around here at night mostly because of critters

 

[Silicon Desert]

I'm puzzled by some of the replies. I have never seen the drop in amperage UNLESS the battery is getting over 90% SOC which of course happens at superchargers and at home as I expect. Right now for example, it is over 102 degrees outside and over 95F in the garage, but my 6 year old MX is charging at 48 amps after I got home and has continued that for several hours. It can get really hot up here in the hills. I've never seen this problem in all the time I have owned that car.

 

[ucmndd]

It won't let me change once charging at 24amp. Although I guess if I start the charge over again it starts at 48 and then I could manually lower it

Right. I mean start a new charging session at 32 or 40 amps. You might want to just do this as a matter of practice.

If I were you I’d also open up and inspect the lugs on the inside of the wall connector. The ambient temp might be exacerbating another problem waiting to happen like a loose hot leg termination.

 

[ucmndd]

I'm puzzled by some of the replies. I have never seen the drop in amperage UNLESS the battery is getting over 90% SOC which of course happens at superchargers and at home as I expect. Right now for example, it is over 102 degrees outside and over 95F in the garage, but my 6 year old MX is charging at 48 amps after I got home and has continued that for several hours. It can get really hot up here in the hills. I've never seen this problem in all the time I have owned that car.

Backing off the current by 50% is exactly what the car/wall connector does when it detects unacceptable voltage drop or an over-temp condition in the charging handle or the wall connector itself.

 

[Silicon Desert]

Backing off the current by 50% is exactly what the car/wall connector does when it detects unacceptable voltage drop or an over-temp condition in the charging handle or the wall connector itself.

Ah that could be it. I've never seen it though.

 

[ewoodrick]

Ah that could be it. I've never seen it though.

Of which the higher ambient temperatures could be helping cause the rollback.

 

[Silicon Desert]

Of which the higher ambient temperatures could be helping cause the rollback.

yea, I think you hit the nail on the head. That makes sense.

 

[ewoodrick]

Which brings us back to my previous statement

"Before I do anything, I'd wait for the temps to drop a bit."

 

[rpiotro]

Right. I mean start a new charging session at 32 or 40 amps. You might want to just do this as a matter of practice.

If I were you I’d also open up and inspect the lugs on the inside of the wall connector. The ambient temp might be exacerbating another problem waiting to happen like a loose hot leg termination.

Like the circuit breakers in your home, the lugs on that wall charger have a torque spec. 50 in. lbs. if I remember correctly but verify that number if you are going to check it.