Charging issues

[TMoore]

I have a 2016 MS 75D that I purchased used from Tesla this past December. As can be seen in the attached image, I've been frequently getting CHG_f018 and CHG_f076 alerts.



I installed a NEMA 14-50 receptacle in the garage with about 40' of 6AWG romex and a 50 amp breaker. I had two gen 1 UMCs that both exhibited this issue. However, I didn't have any issues pulling the full 40 amps and charging has always completed successfully. I think the errors were be generated when the car was woken up, such as by opening a door.

I just got it back from the SC, and they said that the one UMC they tested was bad and gave me a gen 3 UMC as a replacement. However, I still received alerts last night, almost every 30 minutes or hour, all after the car had completed charging. I do have some apps that connect to the car periodically, so that could correlate to my wakeup theory.

The SC is now directing me to have my wiring inspected by a Tesla certified electrician.

I can understand that it could be wiring if errors were generated during while the car was pulling max amps, but the errors are when it's pulling low current and I'm fairly certain that it happens when the car wakes up.

I have a friend who has a M3 and a 50A service, so I'm going to take the car over to his house to see if the issue happens there. If it does, then I think that would rule out my house wiring.

Any other ideas for what I can try?

 

[TMoore]

Looks like the image didn't post properly...

 

[NOLA21SGuy]

I have a 2016 MS 75D that I purchased used from Tesla this past December. As can be seen in the attached image, I've been frequently getting CHG_f018 and CHG_f076 alerts.

View attachment 633729

I installed a NEMA 14-50 receptacle in the garage with about 40' of 6AWG romex and a 50 amp breaker. I had two gen 1 UMCs that both exhibited this issue. However, I didn't have any issues pulling the full 40 amps and charging has always completed successfully. I think the errors were be generated when the car was woken up, such as by opening a door.

I just got it back from the SC, and they said that the one UMC they tested was bad and gave me a gen 3 UMC as a replacement. However, I still received alerts last night, almost every 30 minutes or hour, all after the car had completed charging. I do have some apps that connect to the car periodically, so that could correlate to my wakeup theory.

The SC is now directing me to have my wiring inspected by a Tesla certified electrician.

I can understand that it could be wiring if errors were generated during while the car was pulling max amps, but the errors are when it's pulling low current and I'm fairly certain that it happens when the car wakes up.

I have a friend who has a M3 and a 50A service, so I'm going to take the car over to his house to see if the issue happens there. If it does, then I think that would rule out my house wiring.

Any other ideas for what I can try?

Your test seems like a great idea to help rule out your wiring. It is possible one of your conductors has a poor connection. Can you double check that you didn't screw onto the insulation when installing the receptacle?

 

[TMoore]

Your test seems like a great idea to help rule out your wiring. It is possible one of your conductors has a poor connection. Can you double check that you didn't screw onto the insulation when installing the receptacle?

I plan on going over the wiring again to double check, but I would think an issue like this would result in charging failures when pulling the full 32/40A. I had a retired electrician help me with the install. He terminated the 14-50 and I terminated the breaker. It's easy enough to take a look at both, so I definitely will.

 

[Rocky_H]

a NEMA 14-50 receptacle in the garage with about 40' of 6AWG romex and a 50 amp breaker.

How sad is it that I scrutinized this and was surprised and relieved to see a thread where someone installed a 14-50 outlet correctly?

 

[TMoore]

How sad is it that I scrutinized this and was surprised and relieved to see a thread where someone installed a 14-50 outlet correctly?

After doing some more research, I'm not sure that I have. I installed a Leviton 14-50 receptacle from Home Depot and a non-GFCI 50A breaker.

I've ordered a Bryant 9450fr and a GCFI 50A breaker as I think that's what I should have done in the first place. Unfortunately, I installed the Leviton in a single gang box, and I don't think the Bryant will fit. Even if it does, the cover I have probably won't work because the diameter of the Bryant is larger than the Leviton. I haven't been able to find a single gang cover with the larger hole.

I did a test last night where I was able to confirm that the alerts were generated as the car was waking up and turning on the heater and whatnot. I got it to happen consistently three times. I also turned off my monitoring app, so there were no charging errors overnight.

Tonight, I'm going to pull everything apart and tighten down all of the lugs to see if that'll fix it for now. I may return the Bryant if it does as I'm not planning on disconnecting the UMC very often. I'm probably going to install the GCFI breaker as that's code and it's safer.

 

[Rocky_H]

After doing some more research, I'm not sure that I have. I installed a Leviton 14-50 receptacle from Home Depot and a non-GFCI 50A breaker.

Heh, yeah, you are right about that. I was just thinking of the really bare basics of getting the circuit size and wire size right, which a lot of people mess up.
I actually do still have that same thing you have, I am sad to say. I just haven't gotten around to swapping the wall connector on in place of the Leviton outlet, and my install was in 2014, before the GFCI breaker requirement came along in the 2017 NEC changes.

 

[NOLA21SGuy]

Heh, yeah, you are right about that. I was just thinking of the really bare basics of getting the circuit size and wire size right, which a lot of people mess up.
I actually do still have that same thing you have, I am sad to say. I just haven't gotten around to swapping the wall connector on in place of the Leviton outlet, and my install was in 2014, before the GFCI breaker requirement came along in the 2017 NEC changes.

I thought that documentation said the charger has a gfci in it. That may be only with the wall connector.

 

[Rocky_H]

I thought that documentation said the charger has a gfci in it. That may be only with the wall connector.

The mobile connector and the wall connector both do have GFCI protections built into them, but there is a real reason why the electric code would apply that GFCI breaker requirement only for the mobile connector circuits.
On the wall connectors, there are no pins or wires exposed that people could accidentally touch to shock themselves. The mobile connector does have protection from the electronics box and downstream to the charging plug at the car, but it can't protect upstream from that. So where you are holding the plug and plugging it into an outlet, your finger may accidentally slip and touch a prong of the plug while you're standing in a puddle of water, and you have a painful bad day. The GFCI protection in the box can't necessarily detect and protect from that.

Having said that, here's why it's still a little stupid. They wrote it into the code that it relates to the purpose of what people intend to use the outlet for!! So if you are intending to use it for a mobile home, they don't require the GFCI breaker. But if you are intending to charge a car with it, it does need it. Bah. Code requirements shouldn't really be different like that depending on what you're planning to plug in.

 

[TMoore]

I went over to my friend's house who also has a 50A service to see if I could replicate the problem there, which I was able to do twice. As such, I really don't think it's my house wiring. The SC has some wall connectors outside, so I may just see if I can replicate the issue right in front of them with their own equipment. Should be pretty hard to deny at that point

 

[TMoore]

This morning, I went over to someone's house who has a HPWC, and did not get any errors when charging. This afternoon, a neighbor of mine came over to my house with his 2017 P100D, and he got the same charging errors when we plugged into his car.

I received the Bryant 9450fr, so I temporarily replaced the Leviton with it, but that didn't make a difference. I also tried moving the wires in the breaker box to one of the 40A breakers for my A/C to see if it was the breaker, but still got the errors.

Since I get the errors when it's first starting to ramp up the current draw (e.g. 2-3A), I thought maybe it's a vintage drop issue. I don't have the nicest volt meter, but it stayed between 244 and 245 the entire time while the car was generating charging errors.

At this point, I'm at a loss. I don't really want to pay a Tesla certified electrician $125 to look at it because I really don't think anything's wrong. I guess my biggest concern is that they'll end up charging me a bunch to try and fix it and then it still doesn't fix it. I guess I'd have an even stronger argument against Tesla that there's an issue with the car (either physical or software). I could try to get them to reimburse me for the electrician, but I suspect that'd be an uphill battle.

 

[NOLA21SGuy]

This morning, I went over to someone's house who has a HPWC, and did not get any errors when charging. This afternoon, a neighbor of mine came over to my house with his 2017 P100D, and he got the same charging errors when we plugged into his car.

I received the Bryant 9450fr, so I temporarily replaced the Leviton with it, but that didn't make a difference. I also tried moving the wires in the breaker box to one of the 40A breakers for my A/C to see if it was the breaker, but still got the errors.

Since I get the errors when it's first starting to ramp up the current draw (e.g. 2-3A), I thought maybe it's a vintage drop issue. I don't have the nicest volt meter, but it stayed between 244 and 245 the entire time while the car was generating charging errors.

At this point, I'm at a loss. I don't really want to pay a Tesla certified electrician $125 to look at it because I really don't think anything's wrong. I guess my biggest concern is that they'll end up charging me a bunch to try and fix it and then it still doesn't fix it. I guess I'd have an even stronger argument against Tesla that there's an issue with the car (either physical or software). I could try to get them to reimburse me for the electrician, but I suspect that'd be an uphill battle.

What's your neutral to ground voltage? What is the resistance between each leg in the charger's terminals and same leg in the sub-panel? What is the resistance between each leg and ground?

I'm down to thinking you could have some induced voltage due to a neutral to ground bond somewhere, or you could have high resistance somewhere. Last few options are bad charger and bad wire. After that it's a good mystery that I would like to take a nice scope and check out.

 

[Babaron]

I get these alerts all the time but my car charges just fine anyway. If yours is also charging fine, you may want to just ignore them as I do.

 

[TMoore]

What's your neutral to ground voltage? What is the resistance between each leg in the charger's terminals and same leg in the sub-panel? What is the resistance between each leg and ground?

I'm down to thinking you could have some induced voltage due to a neutral to ground bond somewhere, or you could have high resistance somewhere. Last few options are bad charger and bad wire. After that it's a good mystery that I would like to take a nice scope and check out.

It's my understanding that the UMC does not use the neutral in the 14-50 plug. If that's true, then I would expect that any neutral/ground bonding issues wouldn't be noticed by the UMC. However, if there was an induced voltage on the ground from something, then I suppose that could be an issue. That said, the ground to neutral voltage at the 14-50 was 0.

Regarding high resistance, I would expect that to cause an issue when the car is pulling the full load, which would drive the voltage down. In my case, the charging errors occur when the car is first pulling 2-3A, but then eventually clear and it charges just fine.

I get these alerts all the time but my car charges just fine anyway. If yours is also charging fine, you may want to just ignore them as I do.

This is probably the right answer as I really think this is a software issue with the car, but having spurious errors in the logs drives me insane.

I asked Tesla for clarification on the CHG_f018 and CHG_f076 alerts as I can't seem to locate any details in the user manual. Hopefully they'll give me some useful information

 

[TMoore]

I reached out to Tesla customer service about the two errors, and here's what they said:

CHG_f018 - the charging process was interrupted due to an increase of line current above the limit. Disconnect cable and retry

CHG_f076 - current is over the limit. Unable to charge please disconnect and try again

It seems to me that there are only two reasons why the current could go over the limit:

1. The voltage is dropping from the inrush current
2. The car is trying to pull too much power during the charging ramp-up

While #1 is definitely possible, I would assume that there would also be errors associated with a low voltage condition, which there are not.

I did some more testing last night, and I discovered that if I plug in the charger while the car is awake and running all of the accessories, then it starts charging without issue. However, if I close the doors and wait for all of the screens and fans to shut off and then plug in the charger, it will turn on the fans and instrument panel, and then give a charging failed message when it first starts to ramp up the charging current.

Given the results of my testing, I think there is an issue where the car will try to pull too much current from the charger while it is first ramping up the charging current if the charger is plugged in while it's asleep. The issue also occurs if charging has completed and the car wakes up due to the door being opened or starting climate/preconditioning.

I think the next step is to see if the service center has a 14-50 outlet so I can see if the issue occurs there. If so, then it'll be difficult for them to deny that it's some sort of issue with the car (be it hardware or software)

 

[TMoore]

Took the car to the SC this morning to try and replicate the issue using their 14-50 plug. Turns out they have it wired at 208V instead of 240V, so they can't replicate the issue. They tried to argue that the voltage doesn't matter and it's only the amperage, which I disagree with because the issue happens when the car is only pulling 1-2A. I tried it at 120V, and that works just fine. I really think it has to do with the voltage, but now I have no way to prove it to them.

 

[TMoore]

The Tesla certified electrician came by yesterday after I got home from the service center. He tightened down a few connections and re-terminated the 14-50 outlet, but the car still threw the errors after he was done. He agreed that it's the car.

I've requested that the service center modify one of their 14-50 outlets to be 240V instead of 208V so that they can actually replicate a residential scenario. I've also requested that they reimburse me the $175 I paid for the electrician to tell me that it's the car and not the house. We'll see what happens

 

[random155]

V

The Tesla certified electrician came by yesterday after I got home from the service center. He tightened down a few connections and re-terminated the 14-50 outlet, but the car still threw the errors after he was done. He agreed that it's the car.

I've requested that the service center modify one of their 14-50 outlets to be 240V instead of 208V so that they can actually replicate a residential scenario. I've also requested that they reimburse me the $175 I paid for the electrician to tell me that it's the car and not the house. We'll see what happens

Very interesting. Keep us posted and good luck.

 

[Rocky_H]

I've requested that the service center modify one of their 14-50 outlets to be 240V instead of 208V so that they can actually replicate a residential scenario.

Their building doesn't have a 240V supply--commercial and industrial buildings generally don't. They would have to go buy a transformer to install on a circuit in the building to convert that, and I think there's little chance of that.

He tightened down a few connections and re-terminated the 14-50 outlet, but the car still threw the errors after he was done. He agreed that it's the car.

But how would that make sense? You said this:

This afternoon, a neighbor of mine came over to my house with his 2017 P100D, and he got the same charging errors when we plugged into his car.

Using your charging cable on your outlet, his car showed the same errors. So it's not your car.

This morning, I went over to someone's house who has a HPWC, and did not get any errors when charging.

And your car on his wall connector did not give any errors.

You're doing a good job trying to isolate the variables, but here's what I'm seeing. It seems to point to your charging cable being bad. Did you use your cable when you were at the service center? I suppose it could be possible that your cable is bad in such a way that it has a problem with the voltage levels, where it decided to not throw errors on 208V but does at about 240V.

 

[TMoore]

Their building doesn't have a 240V supply--commercial and industrial buildings generally don't. They would have to go buy a transformer to install on a circuit in the building to convert that, and I think there's little chance of that.

Actually, 240V is standard single phase power running into any residence/building. To get 208V, you have to have three phase running into the building. The SC does have a row of HPWCs that are connected to 240. The 208V outlets are all in the shop, which is where the previous dealer probably had various equipment plugged in.

Using your charging cable on your outlet, his car showed the same errors. So it's not your car.

We tried his UMC as well. The current tally is that I've tried four different UMCs at my house and another UMC at another house. All produce the same issue.

And your car on his wall connector did not give any errors.

This is the one thing that hasn't made sense to me. However, I didn't look at the voltage in all of these scenarios, so that could be a contributing factor.

You're doing a good job trying to isolate the variables, but here's what I'm seeing. It seems to point to your charging cable being bad. Did you use your cable when you were at the service center? I suppose it could be possible that your cable is bad in such a way that it has a problem with the voltage levels, where it decided to not throw errors on 208V but does at about 240V.

The first thing the SC did was replace my gen 1 UMC with a gen 3 UMC. Considering the number of cables that I've tried, I don't think it's the cable.