After using a NEMA 14-50 garage outlet for 5 years, I began to have problems. The outlet was installed as a EV charging option by the builder. I began to occasionally see a warning that the Model Y was lowering the charge rate from the standard 32 amp charge rate to 16 amps because the charging cord was sensing high temperatures at the outlet. The car still charged but at half the charge rate, so twice as long. It would only occasionally do this. Perplexing, but I determined that I would plug the car in daily and usually would only charge for 40 or 50 miles a day. That's only charging a little over an hour. Occasionally, I would need to charge from a remaining range of 60 or 70 miles so the length of time to charge was closer to three to four hours. There's nothing in our houses that would ever require pulling 32 amps for four hours! The wall socket the builder used in the install was the cheapest thing he could buy. That's typically a Leviton or similar at a cost of less than $10.00. After 5 years of use, mine was starting to fail, showing signs of smoking and greying, possibly caused by arcing. I researched and bought a Bryant (made by Hubbel) model #9450. About 50 bucks. The spec sheet on it shows it is made for EV charging. Although it fit the existing outlet box, it is bigger and heavier duty compared to the original. Because of this, I had to buy and install a bolt on extender and new larger faceplate for the standard metal box that held the original. Home Depot or Lowes carries those, or your electrician can provide it if he is told ahead of his house call. I thought I was okay with no problems for a couple years, but it was a false sense of security. Be safe!
Beware of NEMA 14-50 cheap plugs
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Skipcam
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Having the correct equipment to charge an EV day after day is critical. The well respected Sandy Munro did a video about this and it is well worth your time to view it. Basically daily charging an EV should be professionally viewed as a continuous duty appliance and not an occasional one-off task. Also the plug needs to be robust enough to allow for repeated plugging and unplugging cycles.
I had the same problem with my Leviton 14-50 overheating and causing the charge rate to drop. I also replaced it with a Bryant a couple of years ago and it has been fine since.
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You bring up a common issue, although it's not the fault of the "plug" as you state, but the Outlet as you show. Fires have started because of cheap outlets. Not only that, besides the danger of it, the excessive heat generated by small contact surface is also costing you energy. The best way is to hard wire your chargers. I happen to use a Mobile Connector because I don't need anything faster so I do use the outlet, but I use a good one. Stick to Hubbell, Bryant, Eaton (WD125), or Leviton (8375).
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You can also get corrosion when the plug is never removed. Occasional removing the plug and reinserting it can help to clean the contacts.
Your comment about the wire connections is good, too... it wouldn't hurt to occasionally tighten these (if you are comfortable and knowledgeable with electrical systems).
All of this is why I like my hard wired 48 amp charger (Emporia). Or for a wall plug I like a surface mount - easier to detect heat and it can dissipate heat better.
2024 Tesla Model Y LR AWD, 2019 Chevy Volt
Pat H
I also live in Florida and certainly know how hot it can get in the garage, especially with south facing doors. Myself and most of my neighbors have installed mini-split AC units in the garage. Monthly electric charge is minimal and only in warm months. I keep it set to 78 degrees.
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Just make sure it's the correct model of Hubbell or Bryant since you can buy both industrial and residential grades of NEMA 14-50 receptacles from both of those brand names.
You want a Hubbell 9450A or Bryant 9450FR (same thing marketed under a different brand).
You do NOT want a Hubbell or Bryant RR450F (their "residential-grade" NEMA 14-50 receptacle).
There's no reason to spend twice as much on the Hubbell 9450A over the Bryant 9450FR - they're made by the same company in the same US factory to the same specifications.
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I was thinking of doing just that. How did you vent it? I just have a windowed door.
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If you adopt a mini-split, there would be a small hole cut in the wall for the pipes to pass between indoor and outdoor portions of the unit.
I went through the same thing and decided to just get a wall charger! But I do appreciate the car telling me of the problem.
The units are self venting And ductless. There is a unit mounted high inside on an outside garage wall. On the other side of that wall is a suitcase sized compressor unit on the ground. The two are connected by a cover or channel that protects and conceals the refrigerant lines, electrical wiring, and condensate drain line that run between the outdoor mini-split compressor (condenser unit) and the indoor air handling unit. You control with a handheld wireless thermostat control. You can paint the wall cover to match the house or leave it white. Every AC manufacturer makes a mini split. You can buy one that just has AC or one that heats and cools. Cost difference is almost nothing so get the one that heats and cools. Your wife will love coming home and getting in/out of the car without it being stifling hot! So will your cars!
2023 Model Y, Dual Motor, Extended Range, 7 Passenger (Ha!), Towing
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Hi. There is a great solution for this. Even though the 14-50 is a code compliant selection, the typical outlet you reference is normally for appliances that dont have sustained loads for hours on end. Like a dryer. There is a great solution. Legrand has an EV charging rated NEMA receptacle. Check it our here 50A Weather-Resistant Electrical Outlet for EV Chargers | Power Outlets | Outlets and Receptacles | Wiring Devices
These have more rugged terminals and higher temp plastics to handle the heat from long charging sessions at high amperage. There is no code requirement for this, yet, but the inspectors are pushing for a better solution. These are weather resistant too. Great for outdoor installation in proper enclosures.
I replaced my electric dryer circuit with an inexpensive 14-50 outlet. Since I did the work myself, I saw that the circuit breaker was rated at 30 amps. Moreover, so was the installed wiring.
The thing is, even though the breaker is rated for 30 amps, the National Electric Code (NEC) says to run a circuit at 80% of full load if the load runs for longer than 3 hours. Hence, I set my M3 to only pull 24 amps when I charge at home. I then waited for 3 hours of charging and placed my hand on the plug. It wasn't discernably warm nor was the conduit nor was the plug housing so I reckoned even though I didn't spring for $90 outlet, I wasn't creating a hazard.
I've experimented with the load setting and at 27 amps (90%) the plug is slightly warm. Reckoning that slightly warm over the years might not be good for the plug, I've dialed it back.
tl;dr Don't pull more than 80% of the circuit breaker's rating.
The thing is, even though the breaker is rated for 30 amps, the National Electric Code (NEC) says to run a circuit at 80% of full load if the load runs for longer than 3 hours. Hence, I set my M3 to only pull 24 amps when I charge at home. I then waited for 3 hours of charging and placed my hand on the plug. It wasn't discernably warm nor was the conduit nor was the plug housing so I reckoned even though I didn't spring for $90 outlet, I wasn't creating a hazard.
I've experimented with the load setting and at 27 amps (90%) the plug is slightly warm. Reckoning that slightly warm over the years might not be good for the plug, I've dialed it back.
tl;dr Don't pull more than 80% of the circuit breaker's rating.
The real question is how fast you NEED to charge. I have a NEMA 14-50 outlet with #6 wire and I normally charge at 12-16A.
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To be code-compliant, you should have installed a NEMA 14-30 outlet. This is similar to a 14-50, but with a differently-shaped neutral pin.
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There's generally no reason to charge slower than what your car and equipment is capable of. Charging more slowly is less efficient.
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For a few dollars more, the proven Bryant 9450FR (virtually identical except in branding to the Hubbell 9450A) is in stock at Grainger. There's no reason to buy the 9450A over the 9450FR and there's little reason to buy anything else other than a 9450FR. It just works.
Isn't it better for a battery's longevity to slowly charge it? Moreover, fewer of the watts are being lost to heat loss.
Not really, that primarily impacts charging at L1 (80%) vs L2 (90%)
Is the higher efficiency due to conductor size difference between L1 and L2?
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