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Plug Adapter on my Universal Mobile Connector has melted...

joepruitt

Seattle Sig Red #497
I plugged in the ModelS today and the power ring turned red. Looked at the Universal wall connector and it was red. I tried unplugging it and replugging it in and no better. I then took the NEMA 14-50 adapter off from the cable and this is what I found.

895228_10151571328101672_775761048_o.jpg


I've got a 50-amp dedicated line from a single breaker into my garage so I'm only wondering if this could have been some sort of power surge. I called service today and was able to talk to a tech after hours (more awesome Tesla service) and he said he hadn't heard of this happening before.

Meanwhile, I'm stuck in Sammamish without charging for the weekend. Luckily I have a 85kw battery so I should be good until I take it into the service center on Monday. They said they have extra cables I can swap this one out for. My main concern is a fire hazard if this happens again. Anyone have any ideas on how to troubleshoot on my end?
 

mitch672

Active Member
Jul 1, 2012
1,861
15
Stoughton, MA
I know this not the first time this has happened to a UMC, "Cinergi" (Ben) had a similar problem with his, and it needed to be replaced. By any chance have you been using 208V, more than 240V? I think some of these UMCs might have manufacturing defects where the wire connecting to the UMC socket possibly has a high resistance connection, causing the pin to heat up more, leading to an early failure of the socket...
 

joepruitt

Seattle Sig Red #497
Not sure what it was using volt-wise and I can't check it now. Service did say they would replace the cable so they are covering it with the warranty. I'm more concerned with it happening again. I was an early owner so hopefully service can tell me more about the problem when I take it in on Monday.

-Joe
 

Discoducky

P100DL, 2021 M3, 3 CT reservations and counting
Dec 25, 2011
3,429
3,327
Seattle
So, we are traveling from Issaquah (right next door to Sammamish and if we were home you could use our 14-50) and are currently in Palm Springs when our UMC failed. I also saw the red ring, but my cable looks other fine than the metal locking tab at the top was pushed down and was touching the closest pin. I called 877-79-TESLA and talked to TJ who will try to get us in touch with the LA service center to get a new cable sent out Monday. Clearly they are having issues with the UMC's.

Here's what mine currently looks like. I've bent the tab and it engages properly, but the cable still doesn't work.

DSC08542.jpg


Thank goodness we have had a J1772 charger within our remaining range!
 
Last edited:

FlasherZ

Sig Model S + Sig Model X + Model 3 Resv
Jun 21, 2012
7,024
1,013
Looks like a bit of arc'ing took place there, I hope it's a one-off. I was a bit concerned with the size of the pins on the adapter, they seem a bit small for 50A rating.

- - - Updated - - -

So, we are traveling from Issaquah (right next door to Sammamish and if we were home you could use our 14-50) and are currently in Palm Springs when our UMC failed. I also saw the red ring, but my cable looks other fine than the metal locking tab at the top was pushed down and was touching the closest pin.

Red ring, red light on UMC, or both?

Could be a bad receptacle / ground / etc. supplying power. I assume you've tried it at different places on different receptacles?
 

cinergi

Active Member
Sep 17, 2010
2,176
40
MA
Joe -- did you swap the adapter on the end of the MC recently (e.g. to the NEMA5-15 for a 120 connection and back to the NEMA15-50)?

Mine failed in a similar way; the material it's made out of can withstand (melt, but not start on fire) some ridiculous temperatures (I measured it -- forget the numbers I saw). It's still obviously concerning and a safety hazard (at the very least, you'll get burned touching that plug while it's charging). I'm sure they'll send yours in to the engineers like they did mine and study it.
 

Discoducky

P100DL, 2021 M3, 3 CT reservations and counting
Dec 25, 2011
3,429
3,327
Seattle
Red ring, red light on UMC, or both?

Could be a bad receptacle / ground / etc. supplying power. I assume you've tried it at different places on different receptacles?

Red light on UMC, 4 flashes (https://www.teslamotors.com/sites/default/files/blog_attachments/ms_mobile_connector_guide.pdf) and manual says it's lack of ground. It's also a red ring on the charge port on the car. Another outlet shows green on the UMC, but doesn't work on the car. I'm thinking about rebooting the car (center and 17" display) to see if I can get it to work.

Another question I'd like to know if the adapter locking tab on the cable (wall outlet side) has an electrical connection? I'm assuming that it does since the UMC manual says that 5 flashes is "Sense fault circuit" which is "Make sure the Mobile Connector's adaptor is properly attached". SO if I don't get 5 flashes I'm assuming that the tab is locking properly.
 

FlasherZ

Sig Model S + Sig Model X + Model 3 Resv
Jun 21, 2012
7,024
1,013
Red light on UMC, 4 flashes (https://www.teslamotors.com/sites/default/files/blog_attachments/ms_mobile_connector_guide.pdf) and manual says it's lack of ground. It's also a red ring on the charge port on the car. Another outlet shows green on the UMC, but doesn't work on the car. I'm thinking about rebooting the car (center and 17" display) to see if I can get it to work.

Another question I'd like to know if the adapter locking tab on the cable (wall outlet side) has an electrical connection? I'm assuming that it does since the UMC manual says that 5 flashes is "Sense fault circuit" which is "Make sure the Mobile Connector's adaptor is properly attached". SO if I don't get 5 flashes I'm assuming that the tab is locking properly.

The sense fault circuit has to do with the UMC's detection of which adapter is there. The locking tab is not part of that, from what I have seen.

I helped troubleshoot an issue a week ago where a NEMA 14-50 receptacle had a bad ground clasp; when you held the plug a certain way it would work but then it would stop after detecting a ground fault. I had to "adjust" the ground pin so that it would hold the ground pin effectively.

It *could* be that there is a broken connection to the ground pin, but I'd start looking at the circuit(s) first.

I have found that if the UMC detects a ground fault, the car will display a red ring. Fix the power problem and you'll likely get it to work.
 

Discoducky

P100DL, 2021 M3, 3 CT reservations and counting
Dec 25, 2011
3,429
3,327
Seattle
The sense fault circuit has to do with the UMC's detection of which adapter is there. The locking tab is not part of that, from what I have seen.

I helped troubleshoot an issue a week ago where a NEMA 14-50 receptacle had a bad ground clasp; when you held the plug a certain way it would work but then it would stop after detecting a ground fault. I had to "adjust" the ground pin so that it would hold the ground pin effectively.

It *could* be that there is a broken connection to the ground pin, but I'd start looking at the circuit(s) first.

I have found that if the UMC detects a ground fault, the car will display a red ring. Fix the power problem and you'll likely get it to work.

Using known good receptacles and both adaptors fit/lock properly now, the light turns green on the UMC and when connected to car does NOT lock into the car and does NOT charge. I'm currently charging from J1772 and it's nearly fully charged. I'm bummed that the UMC does NOT indicate their is an issue. I'd rather get a known good UMC to test before doing any further troubleshooting.
 

FlasherZ

Sig Model S + Sig Model X + Model 3 Resv
Jun 21, 2012
7,024
1,013
Using known good receptacles and both adaptors fit/lock properly now, the light turns green on the UMC and when connected to car does NOT lock into the car and does NOT charge. I'm currently charging from J1772 and it's nearly fully charged. I'm bummed that the UMC does NOT indicate their is an issue. I'd rather get a known good UMC to test before doing any further troubleshooting.

Does the ring stay white, or turn blue, or some other color? Does the car show any indication that you've connected a charge connector?
 

qwk

P130DL
Dec 19, 2008
3,024
766
Using known good receptacles and both adaptors fit/lock properly now, the light turns green on the UMC and when connected to car does NOT lock into the car and does NOT charge. I'm currently charging from J1772 and it's nearly fully charged. I'm bummed that the UMC does NOT indicate their is an issue. I'd rather get a known good UMC to test before doing any further troubleshooting.
I had the exact same problem. Bad UMC.
 

Discoducky

P100DL, 2021 M3, 3 CT reservations and counting
Dec 25, 2011
3,429
3,327
Seattle
Does the ring stay white, or turn blue, or some other color? Does the car show any indication that you've connected a charge connector?

White, no indication the UMC has been inserted. But I nearly fully charged from J1772 today.

I had the exact same problem. Bad UMC.

How long did it take to get a new one from TM? I've been told that the LA store will be calling tomorrow morning and after triage *could* overnight one from their or another close store.
 

qwk

P130DL
Dec 19, 2008
3,024
766
They overnighted a UMC from the service center( used), because they are on back order.
 

joepruitt

Seattle Sig Red #497
Just got back from service where they replace my UMC. They looked at it right away and said it had to be replaced anyway because it was an early model and I heard something about a tech note on the 14-50 adapter. For those early sig owners out there, it might not be a bad thing to call your local service and ask them if you need to get yours replaced.

Bottom line is that Tesla service rocks. They had me in and out in 15 minutes with a brand new UMC and adapter, tested the connection, and installed my under-display cubby that I never got on the initial delivery.

-Joe
 

FlasherZ

Sig Model S + Sig Model X + Model 3 Resv
Jun 21, 2012
7,024
1,013
I purposely charge at either 30 or 40 amps, never at 50 amps that that my line is capable of.

This is probably the most misunderstood portion of EV charging loads and circuit capacity.

Your branch circuit and receptacle is rated for 50 amps intermittent load. The NEC distinguishes intermittent load from continuous load, which is defined as load applied constantly for 3 hours or more. Furthermore, NEC dictates that all EV charging loads, regardless of expected charge time, are to be treated as continuous load.

Compare an EV load, which draws a constant amount of current, to that of an electric oven or range, where the elements cycle on and off to maintain particular heat settings, or to an air conditioner unit, where the compressor cycles on and off. Because the EV charging load never cycles off until the charge is complete, there is a much greater chance for a significant heat build-up, and in some cases, a 30 amp continuous load on a 30 amp rated receptacle has resulted in complete destruction of plugs and/or receptacles.

This is why the NEC requires the rating of branch circuit wiring, devices, and overcurrent protection to be at least 125% of the continuous load; hence the 40A charging limitation on a 50A circuit, and the 80A charging limitation on a 100A HPWC circuit.
 

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