What is a "Relay/Contactor Fault" Indication on Gen 2 Mobile Connector?

[ruralectric]

I recently plugged my brand new M3 into a new home 30A dedicated circuit via the Gen 2 Mobile Connector and
NEMA 14-30 adapter. Prior to this I had been charging strictly via 110V, Supercharger or J1772. Everything went fine for a couple of hours and then I received a "charging interrupted" message on my phone. The MC displayed a "no green, 3 red" indication, a "relay/contactor fault" according to the manual. Unplugging the charger from the wall cleared the condition. Upon further observation I discovered that the condition occurs coincident with startup of the home furnace blower (but does not happen with every blower cycle). If left on it's own, it takes about 30minutes before the condition self clears and charging commences again. Of course charging stops again when the blower motor next starts.

There appears to be no correlation between the state of the blower and clearing of the condition, except that a blower start may cause the fault to occur if charging when the blower starts. The blower is on a completely different circuit. Yes, old house, and we have observed a small voltage drop (1-2V at the NEMA 14-15) whenever the blower starts. Of course, since it's winter, the furnace blower cycles at regular intervals and so the only way to get a timely charge is to shut off the furnace. Brrr.

Does anyone know exactly what a "relay/contactor fault" is? Are we talking about MC components or car components? And does anyone know why it would take so long for the condition to clear?

Thanks much.

 

[eprosenx]

I recently plugged my brand new M3 into a new home 30A dedicated circuit via the Gen 2 Mobile Connector and
NEMA 14-30 adapter. Prior to this I had been charging strictly via 110V, Supercharger or J1772. Everything went fine for a couple of hours and then I received a "charging interrupted" message on my phone. The MC displayed a "no green, 3 red" indication, a "relay/contactor fault" according to the manual. Unplugging the charger from the wall cleared the condition. Upon further observation I discovered that the condition occurs coincident with startup of the home furnace blower (but does not happen with every blower cycle). If left on it's own, it takes about 30minutes before the condition self clears and charging commences again. Of course charging stops again when the blower motor next starts.

There appears to be no correlation between the state of the blower and clearing of the condition, except that a blower start may cause the fault to occur if charging when the blower starts. The blower is on a completely different circuit. Yes, old house, and we have observed a small voltage drop (1-2V at the NEMA 14-15) whenever the blower starts. Of course, since it's winter, the furnace blower cycles at regular intervals and so the only way to get a timely charge is to shut off the furnace. Brrr.

Does anyone know exactly what a "relay/contactor fault" is? Are we talking about MC components or car components? And does anyone know why it would take so long for the condition to clear?

Thanks much.

I have not heard of this error before (I presume it is either something new in the car software or it is not very common).

I would very much guess it is the contactor in the UMC itself that does not energize power to the car unless it has communicated with the car and the safety features (GFCI) are happy.

Great sleuthing to see it is coincident to the blower startup! That helps a lot.

Did you have this 30a circuit installed just for the car I am presuming? One easy thing to check is that the connections at the breaker and receptacle are tight and that no insulation is pinched under the terminals on either end.

Can you send a picture of your electrical panel? I am curious what the total service service capacity is? 100a?

My guess is that when the blower comes on it is causing a power quality event (voltage dip) so severe that the contactor in the UMC is loosing voltage and opening unexpectedly.

The other option I can think of is a defective UMC.

If you have the option to try the UMC elsewhere on a similar 30a circuit that could be interesting (or a 14-50 circuit at least).

Things I could think of that may be the cause of the voltage dip:
A bad connection in your 30a circuit (unlikely that this would only show up during furnace startup)
A bad connection inside your breaker panel (bus bar bolts or something), or on the lug connections to the panel from the input wires.
A bad connection in the meter base.
Bad connections back at the utility transformer (or between it and your house).
Insufficient conductor size between the utility transformer and your house or an insufficient sized transformer.

It is fantastic you have tried testing the voltage at the receptacle (I presume you meant 14-30) during blower startup, but I have questions about the methodology. 1. You may need to have the EV circuit under load during blower startup in order to see what is really going on (but this makes it difficult to get access to a test point at the same time). 2. A digital multimeter does not necessary react fast enough to really show what is going on. Power quality events can be sub second in nature and can really cause massive issues in that timeframe.

Note that your power company may have devices they can hook up to your electrical feed that monitor for voltage sags/dips, though they generally don’t pull these out unless you prove a legitimate issue that is causing you issues (I am not sure you are there yet).

I would probably try to rule out my UMC first (can you borrow a different one from a friend or the Tesla Service center temporarily)? And then dive into the potentially difficult to troubleshoot power quality issue.

Good luck and please report back on progress and final disposition! It is massively helpful to others to have information on final resolution documented here!

 

[omgwtfbyobbq]

I recently plugged my brand new M3 into a new home 30A dedicated circuit via the Gen 2 Mobile Connector and
NEMA 14-30 adapter. Prior to this I had been charging strictly via 110V, Supercharger or J1772. Everything went fine for a couple of hours and then I received a "charging interrupted" message on my phone. The MC displayed a "no green, 3 red" indication, a "relay/contactor fault" according to the manual. Unplugging the charger from the wall cleared the condition. Upon further observation I discovered that the condition occurs coincident with startup of the home furnace blower (but does not happen with every blower cycle). If left on it's own, it takes about 30minutes before the condition self clears and charging commences again. Of course charging stops again when the blower motor next starts.

There appears to be no correlation between the state of the blower and clearing of the condition, except that a blower start may cause the fault to occur if charging when the blower starts. The blower is on a completely different circuit. Yes, old house, and we have observed a small voltage drop (1-2V at the NEMA 14-15) whenever the blower starts. Of course, since it's winter, the furnace blower cycles at regular intervals and so the only way to get a timely charge is to shut off the furnace. Brrr.

Does anyone know exactly what a "relay/contactor fault" is? Are we talking about MC components or car components? And does anyone know why it would take so long for the condition to clear?

Thanks much.

I believe it has to do with a large enough voltage drop across the line. I've think I've seen something similar on my Mobile connector and also on DW's Prius charger if I plug them in and move them around while they're in the process of readying/starting to charger. Unplugging/plugging them back in clears the fault on both like you saw.

A 1-2V drop to me doesn't seem like it's enough to cause the fault, but I guess it could be. The start up capacitor on the blower motor could also be in need of replacement and may only trigger a Mobile connector fault when it's cold enough, like the first start in the morning after being off for most of the evening.

Do BAD capacitors work less in the cold?

 

[ruralectric]

@omgwtfbyobbq @eprosenx I owe you two an apology. It was generous of you two to post your thoughts and I completely went dark on you. It was very rude of me and there is no excuse. I am truly sorry. Please forgive me.

I will say that the intermittency of the problem, along with the response that I got from Support pretty much had me balled up fetal on the floor. My workaround when the problem occurred was to charge at night when the furnace wasn't running. Also, the house is not my residence but rather that of friends whom I regularly visit across the state.

I will spare you the details of my repeated contacts with service. Suffice it to say that when I finally did reach someone knowledgable and told them everything, including the part about the furnace fan, the call from start to finish took less than five minutes and went pretty much like this: "Oh. You have a bad UMC. We'll send you a new one. Where would you like it sent?"

In short: A 3 red LED, no green LED pattern indicates either a broken or fused UMC relay. In my case, broken, since it still worked sometimes, but seems to be sensitive to line noise.

I should note that I have not yet received the new UMC, but I will post the outcome when I'm next at the home with the new UMC.

To be sure, I am providing feedback to Tesla Service regarding my experience.

PRO TIP: There is a separate number to call for home charging issues. Unfortunately, the first two people I interacted with did not tell me this and neither knew the interpretation of the UMC status lights. It was not until I tried the online chat that I was given the phone number (I also did not try the online chat right away because the pop-up window is buggy and does not always appear on my Macbook Pro, on more than one browser (an issue I have already reported). I have been given the okay to post the number for home charging support. There is a different number that is a bit buried on the website but they both get you to the same place. Here are both numbers:

Tesla Home Charging Support:
510-249-2490
650-681-6133

Rur

 

[eprosenx]

@omgwtfbyobbq @eprosenx I owe you two an apology. It was generous of you two to post your thoughts and I completely went dark on you. It was very rude of me and there is no excuse. I am truly sorry. Please forgive me.

I will say that the intermittency of the problem, along with the response that I got from Support pretty much had me balled up fetal on the floor. My workaround when the problem occurred was to charge at night when the furnace wasn't running. Also, the house is not my residence but rather that of friends whom I regularly visit across the state.

I will spare you the details of my repeated contacts with service. Suffice it to say that when I finally did reach someone knowledgable and told them everything, including the part about the furnace fan, the call from start to finish took less than five minutes and went pretty much like this: "Oh. You have a bad UMC. We'll send you a new one. Where would you like it sent?"

In short: A 3 red LED, no green LED pattern indicates either a broken or fused UMC relay. In my case, broken, since it still worked sometimes, but seems to be sensitive to line noise.

I should note that I have not yet received the new UMC, but I will post the outcome when I'm next at the home with the new UMC.

To be sure, I am providing feedback to Tesla Service regarding my experience.

PRO TIP: There is a separate number to call for home charging issues. Unfortunately, the first two people I interacted with did not tell me this and neither knew the interpretation of the UMC status lights. It was not until I tried the online chat that I was given the phone number (I also did not try the online chat right away because the pop-up window is buggy and does not always appear on my Macbook Pro, on more than one browser (an issue I have already reported). I have been given the okay to post the number for home charging support. There is a different number that is a bit buried on the website but they both get you to the same place. Here are both numbers:

Tesla Home Charging Support:
510-249-2490
650-681-6133

Rur

Thanks for reporting back!

Let us know when you get the replacement and if it resolves the issue!

Will file this in tbe back of my mind so that the next time we hear it happen we might be able to help someone else!

Good job being persistent!

P.S. I do agree that the home charging folks have been excellent.

 

[dwroth]

Did you ever figure out what was going on? I'm having a similar problem with my UMC, charging a model 3 with the supplied 110v connector. Charged for 1 week just fine, then the three flashing lights. I brought it in to Tesla who confirmed that it was a bad UMC and gave me a new one. The new connector charged successfully overnight, but then quit in the morning, same problem!

Another trip to Tesla, but this time when I plugged it in to show them what was happening, it worked. The guy at Tesla thinks that it is because the UMC detected low impedence in the ground line, but I'm not sure how much to trust that (or how much expense to put into investigating it). He said it's possible that is the relay was partially activated it might cause arching inside the connector, explaining why the first UMC failed.

I'm curious to hear how this resolved for you.

 

[ruralectric]

Did you ever figure out what was going on? I'm having a similar problem with my UMC, charging a model 3 with the supplied 110v connector. Charged for 1 week just fine, then the three flashing lights. I brought it in to Tesla who confirmed that it was a bad UMC and gave me a new one. The new connector charged successfully overnight, but then quit in the morning, same problem!

Another trip to Tesla, but this time when I plugged it in to show them what was happening, it worked. The guy at Tesla thinks that it is because the UMC detected low impedence in the ground line, but I'm not sure how much to trust that (or how much expense to put into investigating it). He said it's possible that is the relay was partially activated it might cause arching inside the connector, explaining why the first UMC failed.

I'm curious to hear how this resolved for you.

My situation is a bit ambiguous, which is why I haven't posted a final outcome: We're now in the warm season and so I haven't been charging while the home furnace blower cycles (though we did test the new UMC with a few cycles of the blower and had no problem). Since the problem with the first UMC was intermittent, I'm waiting until I have more data on new UMC to post a final outcome, which won't happen until the fall.

Just to recap: the problem occurred with my first UMC when charging from an old home with brand new 220V 30A circuit, and the failure would occur occasionally when the furnace blower motor would start. Before I received a new UMC we had a simple workaround: we would schedule the charging after bedtime, when the furnace was off and the blower no longer cycled. I was never asked to return the first UMC and so I leave it plugged in to a 110V outlet at the location where the car is parked when not in use. It's never been a problem with that location, even though connected via a 75ft extension chord. Part of the problem with my situation is a lack of good data. I rarely use the UMC except for those two locations, and had the problem at the one site only during furnace blower startup, and even then only intermittently.

I will report back in the fall when I have more blower cycles on the new UMC!

 

[Mikeydeek]

Did you ever figure out what was going on? I'm having a similar problem with my UMC, charging a model 3 with the supplied 110v connector. Charged for 1 week just fine, then the three flashing lights. I brought it in to Tesla who confirmed that it was a bad UMC and gave me a new one. The new connector charged successfully overnight, but then quit in the morning, same problem!

Another trip to Tesla, but this time when I plugged it in to show them what was happening, it worked. The guy at Tesla thinks that it is because the UMC detected low impedence in the ground line, but I'm not sure how much to trust that (or how much expense to put into investigating it). He said it's possible that is the relay was partially activated it might cause arching inside the connector, explaining why the first UMC failed.

I'm curious to hear how this resolved for you.

I was too getting the 3 red lights and only able to charge for less than a minute. Yesterday Tesla replaced the UMC and all has been good so far. (Am charging on 110v).

 

[Rodneycl]

Howdy. Just letting everyone here know this issue is still popping up. I'm experiencing the same issue in Florida. I actually had more faith in tesla than I did in my home... Ended up changing the dryer outlet I was using from a 3 prong to a 4 prong 14-30R, hoping that adding in the ground wire to the mix would help. ( It's a 2021 M3SR+ so I assumed the new UMC couldn't possibly be the issue.


This did not work. Heading to Tesla tomorrow to try the UMC.

 

[ruralectric]

Howdy. Just letting everyone here know this issue is still popping up. I'm experiencing the same issue in Florida. I actually had more faith in tesla than I did in my home... Ended up changing the dryer outlet I was using from a 3 prong to a 4 prong 14-30R, hoping that adding in the ground wire to the mix would help. ( It's a 2021 M3SR+ so I assumed the new UMC couldn't possibly be the issue.


This did not work. Heading to Tesla tomorrow to try the UMC.

It's actually going on three years now since I encountered this problem and I see that I never posted the followup. In short, we never did figure out the problem. After a number of unhelpful calls to Tesla Service someone pointed out a phone number dedicated to charging issues. A call to that number and I quickly had another UMC sent to me. Didn't even have to return the one that had the problem. The result: The new UMC did exactly the same thing as the old one. We never figured out the why problem occurs, and it only occurs at the one location. I now own two UMC kits.

One thing I didn't try (and haven't yet because COVID put the kabosh on travel to that location): You might try reducing the charge current that the car is drawing. (You can reduce the charge current from the car's charging screen or from the app)

Good luck.

 

[Rodneycl]

Thanks for the reply. I did a lot more testing last night by switching outlets and even using different connectors on the UMC. 5-15, 14-30, 14-50... All having the same issues.

I'll try to change the UMC with hope that works for me.

 

[Rodneycl]

Hi. Just an update. Got the UMC changed and the problem is still occurring. Waiting on the electrician appointment to have the panel looked at.

Thanks

 

[ruralectric]

Hi. Just an update. Got the UMC changed and the problem is still occurring. Waiting on the electrician appointment to have the panel looked at.

Thanks

I'll be very interested to hear what your electrician finds. Let me know, eh? Thanks!

 

[Testronic]

Just adding to this too. UMC gen 1 was working fine, got charging interrupted message, 3 red flashes and red in the car charger port.

Reset has no effect, changed the adaptor plug to the standard to use in a regular 120v receptacle, same issue. Out of warranty and telsa is out of stock for any gen.

Also tried dropping the current via big screen, no effect.


Left it unplugged overnight and tried next day foot 15mins of charge..then charging interrupted back to 3 reds all day.

 

[Outpost53]

When I first got my car I plugged my portable charger in to a 240v outlet I installed and after a few minutes charging interrupted and red lights. Plugged it into a 120v outlet in the same building and it worked fine. Started checking voltages, etc and had 240v between the 2 legs but one leg had 120v against ground, the other showed something like 138 IRC. A little digging and I found out the ground - neutral bond in the panel was poor and had a high impedance. Corrected the issue and it charged fine. I'm guessing the charger checks L1/L2 voltages against ground with 240v but not 120v.

 

[ruralectric]

When I first got my car I plugged my portable charger in to a 240v outlet I installed and after a few minutes charging interrupted and red lights. Plugged it into a 120v outlet in the same building and it worked fine. Started checking voltages, etc and had 240v between the 2 legs but one leg had 120v against ground, the other showed something like 138 IRC. A little digging and I found out the ground - neutral bond in the panel was poor and had a high impedance. Corrected the issue and it charged fine. I'm guessing the charger checks L1/L2 voltages against ground with 240v but not 120v.

If we are talking about 3 flashing reds on a Gen 2 Mobile Connector this just may be the most helpful post yet in this thread. Thank you!