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Charge Amperage Dropping in the middle of the charge, 32 --> 16 Amp

Hi, was wondering if anyone else have been experience the same thing I have. It started sometime this year where my home charging, using a 220v outlet with 50 Amp double breaker, goes from 32 amp to 16. All connections are solid and the plugged to the wall is not hot. Not sure why that is. It's been charging fine from March 2019 til the end of 2021.

Breaker doesn't trip or anything, it just drops amperage while charging. If I unplug the charge (at the car) and replug, it goes back up to 32, therefore, I believe it's the car and not the amperage coming to the car from the house.

Thoughts?

Thanks
 

ATPMSD

Active Member
Mar 12, 2021
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Atlanta, GA
Checkout this thread

 
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Rocky_H

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Feb 19, 2015
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Boise, ID
goes from 32 amp to 16.
That is usually the key indicator that it is the onboard charger in the car that is failing. The smaller range cars are built with a smaller 32A onboard charger, and the bigger battery cars are built with a larger 48A onboard charger. But both are built internally out of individual modules that handle 16A of current each. So the 32A one has two of those, and the 48A one has three of them. So when people see their charging reduce in some increment of 16A, it's usually because one of those internal pieces is going out. This modular build does have the advantage where the part can "fail gracefully", where your charging power just reduces some instead of breaking completely.
 
Also worth checking the error log in your car for 'charge rate reduced due to temperature at outlet.' The car will also drop from 32 to 16 amps when high temperatures are detected (due to loose connections within the outlet, etc) using the UMC on an outlet. It's possible the plug/outlet had cooled off between the time the error was detected and the amps were dropped and when you felt it.
 
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Hello: I am having the issue - And took it in to see the logs of "charge rate reduced - Wall temperature high..", there are no other errors. The one thing that I've noticed in 2 different locations is that the reduction happens at 30 minutes. I also notice that the "T" on the charging block does not light up it is just"esla" when the education happens. I'll test again tomorrow from a different location with a similar 60AMP breaker and L14-50 plug. I've been charging for four years at these two locations, and until two months ago, I never had an issue.
 
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ATPMSD

Active Member
Mar 12, 2021
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Atlanta, GA
Hello: I am having the issue - And took it in to see the logs of "charge rate reduced - Wall temperature high..", there are no other errors. The one thing that I've noticed in 2 different locations is that the reduction happens at 30 minutes. I also notice that the "T" on the charging block does not light up it is just"esla" when the education happens. I'll test again tomorrow from a different location with a similar 60AMP breaker and L14-50 plug. I've been charging for four years at these two locations, and until two months ago, I never had an issue.

Since this is happening at two different locations and the "T" no longer lights up, it certainly appears to be an issue with the mobile connector. It is possible the overheating is due to the adapter not being completely seated in the connector, or you are not full inserting the plug into the outlet. If neither of these apply and if it is a newer unit take it to Tesla for a warranty replacement. Otherwise, you will likely need a replacement.
 
Since this is happening at two different locations and the "T" no longer lights up, it certainly appears to be an issue with the mobile connector. It is possible the overheating is due to the adapter not being completely seated in the connector, or you are not full inserting the plug into the outlet. If neither of these apply and if it is a newer unit take it to Tesla for a warranty replacement. Otherwise, you will likely need a replacement.
What they said, lol. I’m following this thread bc I am having the same error codes appear but I’m using a 6-50 outlet so I’m having a hard time finding anyone else with whom I can bring my MCU to in order to test.

I’m t-o’d bc my electrician used aluminum instead of copper without asking, so I have limited options for replacement outlets (best case scenario I have to find a new one). He ran acceptable aluminum for 14-50 outlets (I can see the neutral when I take the outlet off) but I can find any 14-50 outlets that take copper.
 
I’m t-o’d bc my electrician used aluminum instead of copper without asking, so I have limited options for replacement outlets (best case scenario I have to find a new one). He ran acceptable aluminum for 14-50 outlets (I can see the neutral when I take the outlet off) but I can find any 14-50 outlets that take copper.
Maybe this? Based on the photo, it claims to be aluminum wire compatible, while it has full brass contacts to the plug blades.

Here is a 6-50 outlet that claims to be aluminum wire compatible:

(Assuming you currently have a Leviton outlet, which is aluminum wire compatible, but has steel contacts that touch only half of the plug blades, resulting in higher resistance and heat.)
 
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Maybe this? Based on the photo, it claims to be aluminum wire compatible, while it has full brass contacts to the plug blades.

Here is a 6-50 outlet that claims to be aluminum wire compatible:

(Assuming you currently have a Leviton outlet, which is aluminum wire compatible, but has steel contacts that touch only half of the plug blades, resulting in higher resistance and heat.)
Woah! Thanks for the help! I have an Eaton surface mount, which says is commercial but it definitely gets too warm in the plug from Tesla to the MCU. Also it’s got pretty crappy clamps, but I’m not sure how to describe them as I’m away from home right now.
 

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Don't use the $10 outlet! You need commercial / industrial grade option.
"Industrial grade" is not a useful descriptor.

For example, the Leviton 279-S00 for NEMA 14-50 ( 279-S00 ) says that it is "industrial grade", but the contacts to the plug blades are steel and touch only half of the plug blades, resulting in higher resistance and heat there than in most other outlets which have brass contacts that touch the entire plug blades.
 

ATPMSD

Active Member
Mar 12, 2021
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Atlanta, GA
"Industrial grade" is not a useful descriptor.

For example, the Leviton 279-S00 for NEMA 14-50 ( 279-S00 ) says that it is "industrial grade", but the contacts to the plug blades are steel and touch only half of the plug blades, resulting in higher resistance and heat there than in most other outlets which have brass contacts that touch the entire plug blades.

Interesting. Fortunately we all know the Leviton is not suitable for EV charging.
 
Definitely something I wish I knew before my EV charging line install. I was never asked about product, just what voltage, amps and outlet. But the electrician said he did EV lines so once I gave him the stats, I mistakenly trusted the guy.
To be fair, he may have never seen a failure. Most electricians are going to use the cheapest parts that meet spec, assuming they haven't had problems with them.
 
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ATPMSD

Active Member
Mar 12, 2021
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Atlanta, GA
Too many so called “EV” electricians don’t know much about the needs of EV charging, they just use the term to gain more business. What they do not, but should understand if they want to call themselves EV electricians, is that EVs draw a lot of power for a long time. This leads to two common mistakes:
  1. While the use of an inexpensive 14-50 outlet is fine for things like RVs, welders, saws, etc., it is not suitable when used for charging EVs
  2. Using #6 Romex for a 60-amp circuit, while allowed by code, is again fine for welders, saws, etc. but it does not meet the requirements when used for charging EVs
Unfortunately, if we do not ask the right questions we often do not get the correct results. Caveat emptor!
 
Too many so called “EV” electricians don’t know much about the needs of EV charging, they just use the term to gain more business. What they do not, but should understand if they want to call themselves EV electricians, is that EVs draw a lot of power for a long time.

The fault is in the seller of the parts that are rated for 40A or 50A use that should be suitable for 32A or 40A continuous use (80% of maximum rating) with an adequate margin of safety. Seems like some parts (e.g. Leviton receptacles for 14-50 and 6-50) are only barely capable of sustaining 32A continuous use with very little margin of safety. It is not really the fault of the electrician to trust that the specs of the available parts ensure that they will function properly when installed according to the electrical code. Unless an electrician has gotten a call to replaced an overheated melted receptacle, or happens to have an EV and is using their own home charging, the electrician may never have heard of or seen this issue.
 
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