Charging Goes from 32A to 16A

[FatherTo1]

Wow there's another thread 8 days ago, in the Model 3 forum, with similar behavior!

Mobile connector over heat?

I have the mobile connecter. I have a 50 amp breaker, 6 wire, use a 14-50 plug . Has worked great for last 2 1/2 years. Recently (last 6 months) the connector started getting hot and bumped down from 32 amp to 16 amp. I can unplug, plug back in and it resets to 32A, but after 20 min gets hot and...

teslamotorsclub.com

 

[Rocky_H]

The S/Y are usually set at 32 Amps in the car but this morning I noticed the Y's charging screen was set to 48A, which is odd as no one has touch the charging settings.

That is normal and is the expected behavior. When the car is not plugged in, the charging screen will just be showing the default maximum capability of the onboard charger, which is 48A. Once you plug something into it, the charging equipment will announce to the car the maximum amps it has available, and then the car's screen will switch to showing that value, which is 32A.

 

[Sjohnson20]

I’ve been having the same problem for about a year at my house with my Model 3. I have a Nema 14-50 outlet outside and it was fine for about 3 years and this started. I switched out the mobile connector, switch out the outlet with a new one, still the same.

I traded my Model 3 for a Model Y and it has an all new mobile connector and it’s doing the same thing at my house too.

So, I also have a condo in another state and when I was there last time with the new Model Y the same thing happened! It said charging limited and dropped to 16 amps. It’s a brand new Nema 14-50 outlet and everything done by a different electrician in a different state. What the heck!

 

[FatherTo1]

I’ve been having the same problem for about a year at my house with my Model 3. I have a Nema 14-50 outlet outside and it was fine for about 3 years and this started. I switched out the mobile connector, switch out the outlet with a new one, still the same.

I traded my Model 3 for a Model Y and it has an all new mobile connector and it’s doing the same thing at my house too.

So, I also have a condo in another state and when I was there last time with the new Model Y the same thing happened! It said charging limited and dropped to 16 amps. It’s a brand new Nema 14-50 outlet and everything done by a different electrician in a different state. What the heck!

That is pretty strange. Has Tesla ran any diagnostics on the charging system? At first I thought maybe it is hot Summers but you said this is happening for a year, in two different states.

When you replaced the outlet, what brand did you use? In the other Model 3 thread, link on post #21 above, I shared that one wire screw developed some play after three years so I tightened it and the car resumed charging at 32A. However, I felt the charger and plug were running kind of hot so I swapped in a heavier duty Hubbell outlet and the mobile charger now runs up to 10 degrees cooler than before. So I am wondering if the new outlet isn’t much better than your old one. I assume the Y is Supercharging fine to rule out the onboard charger having an issue?

 

[Sjohnson20]

Both outlets are hubbell. And its done it with 2 different cars. I’ve just lowered to 16 amps now and stopped trying to charge at 32.

I wonder if something in Teslas software has changed? It was fine for 3 years. But maybe it was too hot before but the software is more sensitive now than it used to be and just never reported it?

 

[Empiro]

It sounds like there might be something else going wrong.

Is it possible that the electrical supply in your house has problems? Does it holda steady voltage when charging or does it go up and down? If you increase it to 32A, do you see the voltage drop a lot?

Have you tried charging on a different outlet? It's possible that the wiring to the outlet is bad.

 

[RandyS]

I would try to see on the car's screen what the reported voltage is at the start of the charging session when it is at full power, and then try to see what the voltage is on the screen after the car cuts down the charging current to 16 amps...That will tell you if there is a voltage sag problem (which is more than likely a loose connection to be found)...

 

[sc01292]

This happened to me while I am charging in 105F heat in the sun. So I guessed overheating of the portable charger was the cause. I poured a bottle of cold water on the portable charger and disconnected the charger and reconnected the charged. in 60 sec the problem solved. hided my charger in the shade, and it has been working well so far.

 

[RichardL]

I had the same problem last night in my garage - I have been charging my M3 this way for 3 years without issue at 32 amps.

As everyone is aware it was HOT last night (although San Diego is not as bad as other places).

Will monitor over the next few charges

 

[fiehlsport]

My Dad is an electrical engineer and helped install the NEMA 14-50. We used 6 gauge wire and a 50 Amp breaker. It was a pretty straight-forward install as the panel was directly on the other side of the wall. It has been working fine for the past three years for our Model S and now Model Y.

The S/Y are usually set at 32 Amps in the car but this morning I noticed the Y's charging screen was set to 48A, which is odd as no one has touch the charging settings. Anyways, I dialed it back to 32A and plugged it in for 20 minutes and it seemed to charge fine. The mobile charger felt warm during the brief 20-minute charging, not hot but definitely warm. I can't remember if it's supposed to be warm. I will hit it with a temperature gun later tonight to get a reading. Will also remove the junction box cover and peek at the wire connections.

The Mobile Connector can only do 32A - you don't need to manually reduce the charge rate in the car from 48A.

 

[SilverString]

No one has mentioned if the outlet is getting hot. The mobile chargers sense the heat at the plug and if it gets too hot from the outlet the car will automatically step down to a lower amperage charge.

 

[Sjohnson20]

My outlet doesn’t seem to get hot.

So last night I positioned the mobile connector so it wasn’t hanging with just the plug supporting it and it charged at 32 amps constant.

It was also 75 degrees outside at night so much cooler than it has been. Later this week I’m going to try my other location and prop up the mobile connector so it’s not pulling on the outlet and see if it stays at 32 amps.

 

[Delraybeach]

As someone said before, I supported the charging unit instead of letting it hang loosely from the outlet. The rate then reverted immediately to 32amp again from 16amp.

 

[Richh001]

Take a look at the contact surfaces in the handle and the cars charge port. Are they brown/black nasty looking? This buildup can increase the resistance in the connection making it heat up and cause the system to throttle down the amps. If you feel competent you turn off power at the breaker box, squirt some DeOxit contact cleaner on a Q-tip and clean up the contact surfaces to a nice clean silver color. You may have solved your problem.

 

[Alkhan2]

I have a Nema 14-50 outlet installed with a 50V breaker. When I start charging, it is always at 32A, however, lately before reaching my end point, it will be reduced to 16A. If I reset the breaker or unplug and plug in the charger, it will start charging again at 32A. What could be causing this? Thanks.

My model 3 is 5 1/2 years old. Recently its original 32amp charger did as yours is doing. I thought the 50amp breakers in the garage are getting old or corroding as I live near the ocean. But I have a 40amp model S charger that’s hardly used. I plugged that in and it continues to charge at the 40amp! so I believe the 32amp charger is defective or too old to deliver 32amps. I hope it can be reset or easily repaired.

 

[davewill]

My model 3 is 5 1/2 years old. Recently its original 32amp charger did as yours is doing. I thought the 50amp breakers in the garage are getting old or corroding as I live near the ocean. But I have a 40amp model S charger that’s hardly used. I plugged that in and it continues to charge at the 40amp! so I believe the 32amp charger is defective or too old to deliver 32amps. I hope it can be reset or easily repaired.

It's more likely the plug connection to the wall is bad and overheating. Inspect the outlet both from the front and the back (turn off the breaker first), looking for signs of overheating. If there's no obvious melting or scortching, then charge the car at 32a for 30 min or so (or however long it will charge before going to 16a), unplug from the car, then from the wall, and carefully feel the blades of the plug. They will be warm, but should not be so hot that you can't keep your fingers on them. If they are HOT, then you probably need to replace the outlet and/or tighten the wires at the back of the plug.