If you really want 40 amps from a NEMA 14-50 with a Mobile Connector, the Corded Mobile Connector that does away with the changeable adapters is still available. That solution also solves the thermal issues that have occurred with the UMC in the past. However, at $520, it's more expensive than a Wall Connector.
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New UMC 14/50 limited to 32 amps... WHY?!
- Thread starter SabrToothSqrl
- Start date
mknox
Well-Known Member
This started in Ontario, Canada a couple of years ago. We all had new de-rated UMC sets sent out and were asked to return the originals. There is a ton of information here on the reasons why if you search around.
Yes, the new UMC, like the old one, automatically adjusts its current depending on which NEMA Tesla adapter you use with it. It’ll charge at 32A with a NEMA 14-50 adapter, and 24A with a NEMA 14-30 adapter for instance. And you can still dial the current down from these defaults if you want or need to from the charging screen in your car.
I agree with dhanson865 that this new UMC is a game changer at the $300 price point. Or rather, it would be if it was J1772 compatible. A $300 Mobile UMC that can charge at 32A and is compatible with 6 different plug types is an insane deal compared to anything else out there. I wonder how much of the extra cost of J1772 compatible EVSEs is the licensing cost?
And if you wouldn't cherry pick data to support your flawed position, etc. etc.
You can straight up swap the term wall connector into your whole comment and all of the same statements apply. It has had problems with burning up handles, cables, and fuses running at its "rated" 80A, so the same conclusion applies, but you don't want to admit that. So it's disingenuous to only criticize the mobile cable.
Who has complained about the HPWC having issues at 80a? I've not seen a single complaint about that. I'm not saying there aren't any, but I've not seen them and they are far less than the complaints about the UMC. The UMC fails at 40a (or at least a good majority of them do) the HPWCs work just fine at 80a (or at least the good majority of them do).
The handles are not the same as the UMC failing. The UMC and the HPWC share the same handle. Claiming that because the handle on the HPWC fails is a red herring. If there's a flawed handle design, it's shared between both pieces of equipment. Cables, same deal. A fuse blows on a HPWC? So the fuse was... doing its job?! Holy crap, stop the presses!
The HPWC can run all day long at 80a and not fluctuate in its power delivery. Many (if not most) UMCs can't run more than a few minutes at 40a without fluctuating. The UMC is unstable, period. End of story. Deal with it.
Whatever makes you feel better, though. I'm done arguing with you. It's like talking to a brick wall. You don't even understand what you're arguing about.
The handles are not the same as the UMC failing. The UMC and the HPWC share the same handle. Claiming that because the handle on the HPWC fails is a red herring. If there's a flawed handle design, it's shared between both pieces of equipment. Cables, same deal. A fuse blows on a HPWC? So the fuse was... doing its job?! Holy crap, stop the presses!
The HPWC can run all day long at 80a and not fluctuate in its power delivery. Many (if not most) UMCs can't run more than a few minutes at 40a without fluctuating. The UMC is unstable, period. End of story. Deal with it.
Whatever makes you feel better, though. I'm done arguing with you. It's like talking to a brick wall. You don't even understand what you're arguing about.
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Here--three pages worth. It's been a pretty active thread.
Melted HPWC handle
And a few more.
My HPWC almost melted down!!!
HPWC Failure
HPWC Burned Up (Yikes!)
I've summarized these before:
HPWC Burned Up (Yikes!)
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Wow, look at that. You found a bunch of threads showing failed parts that are... wait for it... also in the UMC.
But we aren't talking about melted parts. We are talking about unstable power delivery. Show me an instance of unstable power delivery from the UMC. I've already shown you multiple instances of unstable power delivery from an UMC.
I'm waiting (I suspect I'll be waiting a long time).
Listen, unless you come back with something that shows the HPWC is unstable at 80a, like the UMC is unstable at 40a, you are just plain wrong. I'm done arguing with you. You can't bring anything to the table but strawmen and irrelevant "proof" that doesn't apply to the discussion.
I am not going to respond further until you provide a shred of evidence for your position, that being that the HPWC is unstable at 80a.
But we aren't talking about melted parts. We are talking about unstable power delivery. Show me an instance of unstable power delivery from the UMC. I've already shown you multiple instances of unstable power delivery from an UMC.
I'm waiting (I suspect I'll be waiting a long time).
Listen, unless you come back with something that shows the HPWC is unstable at 80a, like the UMC is unstable at 40a, you are just plain wrong. I'm done arguing with you. You can't bring anything to the table but strawmen and irrelevant "proof" that doesn't apply to the discussion.
I am not going to respond further until you provide a shred of evidence for your position, that being that the HPWC is unstable at 80a.
One of our EVSEs is an engineered device rated at 40a output (J1772). The cable is as thick as a commercial water hose. 40a sustained requires 8 AWG wire. Most 8 AWG connections are hardwired connections, or they use a twist lock waterproof commercial interface. 14-50 plugs are primitive when it comes having a long lasting connection that won't overheat in a few years due to corrosion and spring tension. While 14-50 push in (and it's brothers) are a staple of motorhomes, motorhomes seldom can pull 10,000 watts (40 amps), and they use 8/6 ga anyways. It's even a thicker cable than a 40a heavy duty EVSE. I hated that thing. You can barely bend it at 30°F.
Next time you are at a hardware store, grab 3 lengths of 8 ga and play with it. If you like 25' cords, take 3 x 6 ga and play with it.
Remember when dealing with what amounts to a 240 vac extension cord (not armored, laid on ground where it can be damaged) you want overkill. 10 gauge armored wire (in conduit) is OK up to 10 feet.
It depends on how much you are willing to worry about fire and shock hazards. In my many years, I've awoke in 2 burning buildings and can tell you it can give you nightmares the rest of your life. If you are cool with that, there are portable 40a EVSEs out there.
Cliff Notes: You want an EVSE cable/interface that's engineered for life to take heavy abuse and never get hot.
Next time you are at a hardware store, grab 3 lengths of 8 ga and play with it. If you like 25' cords, take 3 x 6 ga and play with it.
Remember when dealing with what amounts to a 240 vac extension cord (not armored, laid on ground where it can be damaged) you want overkill. 10 gauge armored wire (in conduit) is OK up to 10 feet.
It depends on how much you are willing to worry about fire and shock hazards. In my many years, I've awoke in 2 burning buildings and can tell you it can give you nightmares the rest of your life. If you are cool with that, there are portable 40a EVSEs out there.
Cliff Notes: You want an EVSE cable/interface that's engineered for life to take heavy abuse and never get hot.
Totally agree here. The UMCs are just a bad design for regular charging (NEMA outlets included in the blanket statement) of high powered EVs. For portable, occasional/emergency use, sure, bit as a regular charging solution, it's just a host of problems waiting to happen.
Tesla should not encourage this practice; they should include a HPWC in addition to the UMC with every car if requested, including installation. Build it in to the price so those financing can have a proper charging solution.
Better yet, design in the wireless charging. Although the efficiency on that leaves a lot to be desired.
32A is fast enough where you sleep and at that current level is much more broadly depolyable with less thought and concern - and remember Tesla’s goal is to electrify all vehicles. For many older/smaller houses it will be ok to add a 40A breaker to their <150 Amp panel but 50A is too much. I worried about this in our last house with a 125A service.
As another random data point on the old UMC. Mine failed at the changeable plug connector - and I was only using it at 30A!
I had to put a permanent 14-50 plug on.
As another random data point on the old UMC. Mine failed at the changeable plug connector - and I was only using it at 30A!
I had to put a permanent 14-50 plug on.
I think Tesla changed the UMC downward to 32A for a few reasons, the first was in response to electrical code (Ontario, specifically) so Canadians received the "great news" first and were having 40A UMC "ripped from their hands".. not really.
Then there was also overheating issues, not necessarily with the UMC or its handle itself but with house wiring catching fire, receptacles frying, or house wiring melting, etc.. Which doesn't look good for a startup company having things burn to the ground is bad press... "Electrical Charging in Your Garage is More Dangerous Than Possibility of Gas Fumes Exploding"... or whatever headlines, wanting to avoid those.
The reason why receptacles overheated was because of .. drum roll.. poor parts and electrical wiring practices that are within a grey area of code. In other words, the very things that Ontario tries to protect by not allowing 100% full draw on 40A circuit for EV charging. People smacking in 50A breakers is a bad thing to get the UMC up to max thrust when wiring is at best 40A * 0.8 capable of sustained use (code). Dumb users, house fire, but makes Tesla looks bad. EVEN though there's a facility in the car (console) to dial down power draw... requires a person to do that... default is 40A. One way to limit the heat / fire problem is limit the draw, thanks 32A UMC was born! Maybe another way of accomplishing the same thing would have been to software limit the car side the draw to max 32A for anything plugged into the port that is reporting 40A capability.
Shave parts power handling capacity (UMC and car) and shave weight and dollars so prices of things improve.
If you have the stronger 72A onboard charger then the UMC is not enough in any capacity to fill those boots and we're looking at HPWC or equiv ... which means special wiring must be installed. As a job, the electricians cannot ignore the load asked and will install the right breaker, the right wire, etc.. and less fire potential. However, that HPWC can get hot! (Another story).
For me, old car.. got the 80A on-board dual chargers... 40A UMC.. and 80A old fashioned HPWC. UMC is only used mobile... and I typically have a 6-20 head on for everyday but swap it off for 14-50 every two months on some trip... This UMC has had no issues with heat on any part of the connections it has between receptacle and car.
I'm happy to have the 40A setup for UMC and am of the belief every Amp counts when you're on the road and having to use the UMC. Especially when using the car pre-heating modes that suck overhead kW just for heating battery pack and interior.. The allocation (remainder) of the power available for battery charging appreciates that extra 8A of the old UMC.
Typically, though.. on a daily basis it doesn't matter. 6-20 all day at work is enough for my commute and a weekly Supercharge handles weekend run-arounds... I hardly charge at home anymore so that HPWC is mostly gathering dust. It cost me about $7000 to upgrade my house to have a HPWC... 4 years ago was needed. But not today, would never recommend it unless you're using your house a "home base" for a lot of driving radiating out from there. For me, today... a 32A UMC at home would do fine if that were all I had and I would keep it mobile - in the car normally.
Then there was also overheating issues, not necessarily with the UMC or its handle itself but with house wiring catching fire, receptacles frying, or house wiring melting, etc.. Which doesn't look good for a startup company having things burn to the ground is bad press... "Electrical Charging in Your Garage is More Dangerous Than Possibility of Gas Fumes Exploding"... or whatever headlines, wanting to avoid those.
The reason why receptacles overheated was because of .. drum roll.. poor parts and electrical wiring practices that are within a grey area of code. In other words, the very things that Ontario tries to protect by not allowing 100% full draw on 40A circuit for EV charging. People smacking in 50A breakers is a bad thing to get the UMC up to max thrust when wiring is at best 40A * 0.8 capable of sustained use (code). Dumb users, house fire, but makes Tesla looks bad. EVEN though there's a facility in the car (console) to dial down power draw... requires a person to do that... default is 40A. One way to limit the heat / fire problem is limit the draw, thanks 32A UMC was born! Maybe another way of accomplishing the same thing would have been to software limit the car side the draw to max 32A for anything plugged into the port that is reporting 40A capability.
Shave parts power handling capacity (UMC and car) and shave weight and dollars so prices of things improve.
If you have the stronger 72A onboard charger then the UMC is not enough in any capacity to fill those boots and we're looking at HPWC or equiv ... which means special wiring must be installed. As a job, the electricians cannot ignore the load asked and will install the right breaker, the right wire, etc.. and less fire potential. However, that HPWC can get hot! (Another story).
For me, old car.. got the 80A on-board dual chargers... 40A UMC.. and 80A old fashioned HPWC. UMC is only used mobile... and I typically have a 6-20 head on for everyday but swap it off for 14-50 every two months on some trip... This UMC has had no issues with heat on any part of the connections it has between receptacle and car.
I'm happy to have the 40A setup for UMC and am of the belief every Amp counts when you're on the road and having to use the UMC. Especially when using the car pre-heating modes that suck overhead kW just for heating battery pack and interior.. The allocation (remainder) of the power available for battery charging appreciates that extra 8A of the old UMC.
Typically, though.. on a daily basis it doesn't matter. 6-20 all day at work is enough for my commute and a weekly Supercharge handles weekend run-arounds... I hardly charge at home anymore so that HPWC is mostly gathering dust. It cost me about $7000 to upgrade my house to have a HPWC... 4 years ago was needed. But not today, would never recommend it unless you're using your house a "home base" for a lot of driving radiating out from there. For me, today... a 32A UMC at home would do fine if that were all I had and I would keep it mobile - in the car normally.
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whitex
Well-Known Member
I totally agree the lowering came because people have bad wiring, codes not strong enough or clear enough for wiring NEMA 14-50 and people trying to save money on wiring (and home grown "electricians" that connect whatever makes it appear to work).
Just as a point of reference, I've been using a 40A UMC since 2013. First one for 2 years, second coming up on 3 years and used it for a couple of weeks in Ontario Canada, but on a solidly wired NEMA 14-50 (6AWG wire). No problems whatsoever for almost 5 years of everyday 40A charging. Charging stays solid at 40A, no problems, even with HPWC going at 80A from the same main panel (usually we only go 40+48, but have done 40+80 before).
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