Using UMC vs HPWC for all charging at home

[mknox]

Maybe it's the charge port on your car that's defective, causing the UMC handles to break? I plug/unplug my UMC every day for over a year now and haven't had any problems.

Tesla did proactively change my charge port out with my first UMC replacement, but I've gone through 2 more UMCs since then. Oddly, my J1772 adapter, which I use almost daily, has given me no grief whatsoever. It seems to be the contacts in the handle of the UMC getting "loose" and not making a good connection over time as far as I can tell.

 

[David99]

Just because you and others haven't had a problem with your UMC's doesn't discount all the problems other people have had (some multiple times). The fact that people post problems and not trouble free issues, doesn't discount the problems.

The original question was if the UMC or HPWC would be preferable. Pointing to cases of problems with the UMC doesn't automatically make the HPWC more reliable. There have been many reports about it causing trouble as well. Many reports about UMC problems are from early models. They changed the design of the UMC about a year ago. So all reports for the old model don't apply to the new one.

 

[qwk]

I would say the UMCs failed from either being misused or being defective. I (and many other people I'm sure) use their UMC for everyday charging and haven't had a single problem. On a forum like this, you generally only hear from people with problems, not the majority who haven't had issues.

Edit: Except for David who just posted before I did.

Edit2: If the UMCs were really that bad, and not to be used for everyday/daily charging, don't you think that Tesla would (a) re-design them to be more robust, and/or (2) issue a recall of the potentially defective units*, and/or (iii) issue a TSB telling people to either buy an HPWC for everyday charging and only use the UMC for occasional use? So far, they haven't done any of these.

*Yes, I know they recalled one of the adapter plugs. Doesn't count.

Tesla didn't redesign the UMC yet, they only made small internal/external changes. The UMC isn't designed for continuous 10kw use, just like the HPWC isn't designed for continuous 20kw use. If one uses these at the limit all of the time, they will not last.

A recall would have been too expensive, so we have what we have, which were small band-aid changes.

 

[Canuck]

UMC = Universal MOBILE Connector

HPWC = High Power WALL Connector

One is mobile, the other is stationary. The mobile one is not as heavy duty, and much more prone to failure than the heavy duty one. While the heavy duty one has also failed, it has not failed nearly as much as the light weight mobile one.

 

[alin3]

Interesting. I know 3 current Tesla owners that currently use the UMC 100% of the time.

I received an email from Tesla with the following statement:

It's time to prepare for home charging! Most Tesla owners choose to charge their Model S at home overnight. To charge at home you will need a 240 volt NEMA 14-50 outlet or a Tesla Wall Connector installed near your parking space.
As standard equipment, all Model S include a Mobile Connector cable which will plug into a NEMA 14-50 outlet, providing a recharge rate of 29 miles per hour. The majority of Tesla owners use this method for daily charging.

It seems that official Tesla statements acknowledge that using the UMC at home on a daily basis is SOP for most...

 

[Canuck]

It seems that official Tesla statements acknowledge that using the UMC at home on a daily basis is SOP for most...

Isn't that obvious? Cosmacelf also pointed that out in the third post to this thread...

The vast majority of Tesla owners use the UMC. I use the UMC, but decided to buy a second UMC to always leave in the car (since my brain is a sieve). The HPWC is more robust and built better than the UMC - some small minority of UMC owners have had overheating problems with their UMC - the odds of having a problem with an HPWC is far less.

 

[alin3]

Isn't that obvious? Cosmacelf also pointed that out in the third post to this thread...

Not if u use this thread as a representative sample...

 

[TexasEV]

I've charged at 40A almost every night for two years with my UMC, no problems. I leave it plugged into the garage outlet and hang the cable on a hook. There're no reason to take it in the car unless I'm driving out of town.

 

[HankLloydRight]

I've charged at 40A almost every night for two years with my UMC, no problems. I leave in plugged into the garage outlet and hang the cable on a hook. There're no reason to take it in the car unless I'm driving out of town.

Same here, but for 1.5 years.

 

[jerry33]

I've charged at 40A almost every night for two years with my UMC, no problems. I leave it plugged into the garage outlet and hang the cable on a hook. There're no reason to take it in the car unless I'm driving out of town.

Over two years for me. Had one UMC replacement in the early days.

 

[jaguar36]

The mobile one is not as heavy duty, and much more prone to failure than the heavy duty one. While the heavy duty one has also failed, it has not failed nearly as much as the light weight mobile one.

Without having statistics on how many people are using the UMC vs the HPWC there is no way to know what the failure rate is between them. You are just speculating.

The UMC is not 'lightweight' and it is designed for daily use. There have been some failures of them sure, but there are getting close to 100k of them in service now. Far less HPWCs out there.

There are lots of good reasons for getting a HWPC, but trying to lessen the 'stress on the electrical system' is not one of them.

 

[idoco]

Another data point here. UMC charging daily for almost 2 1/2 years. No issues.

This UMC is permanently plugged into a 14-50 and never unplugged. We have a second UMC that stays in the car for travel.

 

[mknox]

Okay, here's something weird: I was speaking with an owner the other day who told me that when he took his car in for service/annual inspection (forget which), Tesla proactively replaced his UMC's NEMA-14-50 adapter with a new one that limits the charging current to 32 amps. This is not the replacement adapter to deal with the melting issue of around a year ago. I already got that replacement. He said something about being told 40 amps was "too much" for the UMC.

I know that in Canada, NEMA 14-50 outlets can be wired with 40 amp breakers and wiring for stoves. Not sure if this is the case in the US, but I believe it is as well. Applying the Continuous Load rule to a 40 amp circuit (80%) equals 32 amps.

Anyone else experienced this?

 

[thedaysbetween]

Okay, here's something weird: I was speaking with an owner the other day who told me that when he took his car in for service/annual inspection (forget which), Tesla proactively replaced his UMC's NEMA-14-50 adapter with a new one that limits the charging current to 32 amps. This is not the replacement adapter to deal with the melting issue of around a year ago. I already got that replacement. He said something about being told 40 amps was "too much" for the UMC.

I know that in Canada, NEMA 14-50 outlets can be wired with 40 amp breakers and wiring for stoves. Not sure if this is the case in the US, but I believe it is as well. Applying the Continuous Load rule to a 40 amp circuit (80%) equals 32 amps.

Anyone else experienced this?

US Customer here. My S85 went in for its first annual checkup. The UMC was replaced and now operates properly at 40A on a 50A breaker.

 

[TexasEV]

Okay, here's something weird: I was speaking with an owner the other day who told me that when he took his car in for service/annual inspection (forget which), Tesla proactively replaced his UMC's NEMA-14-50 adapter with a new one that limits the charging current to 32 amps. This is not the replacement adapter to deal with the melting issue of around a year ago. I already got that replacement. He said something about being told 40 amps was "too much" for the UMC.

I know that in Canada, NEMA 14-50 outlets can be wired with 40 amp breakers and wiring for stoves. Not sure if this is the case in the US, but I believe it is as well. Applying the Continuous Load rule to a 40 amp circuit (80%) equals 32 amps.

Anyone else experienced this?

There must be a communication gap somewhere. Tens of thousands of people are charging with the UMC at 40A. If Tesla was changing this, we'd hear more about it than what one owner thought he heard from one service center.

 

[AmpedRealtor]

Okay, here's something weird: I was speaking with an owner the other day who told me that when he took his car in for service/annual inspection (forget which), Tesla proactively replaced his UMC's NEMA-14-50 adapter with a new one that limits the charging current to 32 amps. This is not the replacement adapter to deal with the melting issue of around a year ago. I already got that replacement. He said something about being told 40 amps was "too much" for the UMC.

I know that in Canada, NEMA 14-50 outlets can be wired with 40 amp breakers and wiring for stoves. Not sure if this is the case in the US, but I believe it is as well. Applying the Continuous Load rule to a 40 amp circuit (80%) equals 32 amps.

Anyone else experienced this?

Perhaps this person simply confused the car's automatic reduction of charge current by 20% if it detects a problem with that function being in the new adapter. There are many owners out there who don't understand these basic things and plenty of service advisors who dispense the wrong information.

 

[scaesare]

Okay, here's something weird: I was speaking with an owner the other day who told me that when he took his car in for service/annual inspection (forget which), Tesla proactively replaced his UMC's NEMA-14-50 adapter with a new one that limits the charging current to 32 amps. This is not the replacement adapter to deal with the melting issue of around a year ago. I already got that replacement. He said something about being told 40 amps was "too much" for the UMC.

I know that in Canada, NEMA 14-50 outlets can be wired with 40 amp breakers and wiring for stoves. Not sure if this is the case in the US, but I believe it is as well. Applying the Continuous Load rule to a 40 amp circuit (80%) equals 32 amps.

Anyone else experienced this?

Did the service center explicitly state this was the expected behavior of the new UMC, or is that just what's he's experiencing when he uses it?

 

[linkster]

I know that in Canada, NEMA 14-50 outlets can be wired with 40 amp breakers and wiring for stoves. Not sure if this is the case in the US, but I believe it is as well.

Most likely there are millions of homes across the U.S. that use a 14-50 with 8-3 Romex on a 2-pole 40 for ovens/ranges as there are 120,000 homes in my neighborhood alone wired this way.

 

[Cottonwood]

Most likely there are millions of homes across the U.S. that use a 14-50 with 8-3 Romex on a 2-pole 40 for ovens/ranges as there are 120,000 homes in my neighborhood alone wired this way.

Having charged with many range outlets, I can confirm this in a few range outlets that I have used. After 20-30 minutes of charging at 40 Amps, the 40 Amp breaker pops, I go find the breaker box, see that it is a 40 Amp breaker, reset it, let it cool for 10 minutes, then start charging again at 32 Amps and all works. Worse yet, I was charging at a 14-30 dryer outlet, that had a 20 Amp breaker feeding some high efficiency European electric dryer. I had to dial the charging back to 16 Amps then.

I now check the breaker size before starting a charge when living off the land...

 

[jaguar36]

Most likely there are millions of homes across the U.S. that use a 14-50 with 8-3 Romex on a 2-pole 40 for ovens/ranges as there are 120,000 homes in my neighborhood alone wired this way.

Wouldn't this be against code? I could see it being overlooked by some inspectors, but on a large scale it shouldn't happen.