Thanks for the response. What would you consider very cold weather?I don't have the link handy, but there is at least one good thread here that details the steps. For a home built in the 70s I would peg your odds as not great, but your first step should be checking the breaker for the outlet's circuit--if it's already 20A, then you should be good (assuming your home was built to code) but you can verify the wiring gauge by shutting off the breaker and pulling the outlet out of the wall so you can see the wiring.
The upgrade for my mom was about $20, including an outlet tester that I bought to check my work afterward. I literally just had to buy a 5-20 outlet, shut off the breaker (which was already 20A), verify the wire gauge, then remove the old outlet and screw in the new one.
There are other options that could work depending on the setup of the garage's circuit(s), including 6-15 or 6-20. Do you own this home? If so, your best bet might be to hire an electrician for an hour to do a quick inspection and see what they suggest. My main point is that given your relatively low weekly mileage, you don't necessarily need a big upgrade all the way to a 14-50 or something to get by. A 5-20 would go a long way. If your electrical panel is in the garage, it may very well be a cheap upgrade even if you can't just make the 5-15 to 5-20 swap like I did.
My mom's car is a 3, but it moved from around 4 mph to 7 mph charge rate with the 5-20. Tesla has a chart here, but it's very conservative. In 'normal' weather, you should beat those estimates. In very cold weather, a 5-15 will largely just maintain charge level.
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It will vary based on how long the car has sat in the cold without being plugged in. I know I've seen it take awhile (a couple of hours) to start actually adding range on a 5-15 when the car has sat for several hours in ~15F temperatures. Basically the car wants the battery to be 'warm enough,' but a 5-15 puts out so little power that it's initially all consumed by heating the battery. Another reason I'd shoot for a 5-20 or better if possible.
Just by a quick search online to identify a 20amp breaker, it appears that if the breaker has a “20” on it then its a 20 amp? Because the breaker says 20 does that mean the outlet is 20 too? My breaker box has quite a few of these 20 breakers
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angus[Y]oung
Active Member
Okay, dumb related question: does the 80% rule not apply to outlet usage like it does to say the Telsa wall connectors? If that's the case, with a NEMA 6-20, would you be limited to 16amps, or do you actually get all 20?
Yes, you're looking for the breaker that applies to the outlet you'd use being marked as a 20A breaker.
Disclaimer: I am not an electrician, nor do I play one on TV. Do your own research to verify what I say. I'm not responsible for any decisions you make. Etc.
If the breaker is 20A, then that *should* imply that the wiring used for that circuit is 12ga or better since 12ga is generally required by code for a 20A circuit. Since the Tesla will be pulling the max rated constant current of 16A for many hours at a time, you want to be sure that the outlet isn't using thinner (eg 14 ga) wiring, which is why I suggest making certain that's the case before proceeding.
If you have a 20A breaker protecting this circuit, and it's running 12ga wiring, then the next step would be to ensure that you don't have any other heavy loads on that circuit. Garage door opener should be fine--I'm talking things that would add significant load to the circuit for more than a few seconds--think shop vac. The car should be the only thing utilizing that circuit heavily.
Finally, I would spend the few extra dollars to get a weatherproof, commercial-grade 5-20 receptacle. I also purchased a receptable tester to verify my wiring work.
Any of our resident actual electrical experts can chime in with corrections/details on this process. Eg @Rocky_H.
It does apply. On a 5-15 (normal outlet), you'll pull 12A. On a 5-20, 16A, etc.
Gotcha. I will have to check to see if the breaker for the outlet I am using is a 20 amp. In terms of draw, it should be the only thing. But as for safety if for SOME reason there is something else high draw, the breaker would pop correct?
Theoretically, yes. When I replaced my mom's, I just wanted to be extra cautious to be safe since I was doing the work myself. She has absolutely nothing else plugged in within her garage other than the opener.
angus[Y]oung
Active Member
Thanks @Zaxxon, great info in your replies here. We are still to-be MY owners and were planning to try 5-15 charging initially to see how it goes (as we are driving less these days still due to the pandemic), with a possible future upgrade to 14-50 or a wall connector down the road, but perhaps 5-20 would be a straightforward upgrade to try. Will give it some consideration.
IMO if the breaker and wiring support it, it's a no-brainer. While both 5-15 and 5-20 are slow, it really is a very noticeable improvement on 5-20.
That indicates it's a 5-15 outlet, which is why you would need to replace the receptacle with a 5-20 to see the improved charge power. The only difference between the 5-15 and 5-20 outlets is the ability to receive the flipped prong used by 20A loads.
Checking the breaker and wiring behind the scenes is to ensure that before you replace the receptacle, you are confident that your circuit is designed to support that 20A load.
And just to be explicit, I should also note that you'll need to buy the 5-20 adapter in order to get the improved power should you swap the receptacle.
Yes, happens all the time, especially in residential settings. There aren't all that many residential appliances that use the 5-20 plug, so many (most?) builders and electricians just install 5-15 outlets even though most circuits these days are wired to be safe for 20A. The two receptacles are extremely similar behind the scenes.
Yes, happens all the time, especially in residential settings. There aren't all that many residential appliances that use the 5-20 plug, so many (most?) builders and electricians just install 5-15 outlets even though most circuits these days are wired to be safe for 20A. The two receptacles are extremely similar behind the scenes.
Bad news is that I just identified the breaker that the outlet is on and its 15 amps.
If that is only receptacle on the 15amp circuit an electrician can rewire the circuit to be 240V/15A. The breaker would be changed to a double pole 15A circuit breaker, the existing NEMA 5-15 receptacle could be changed to either a hard wired connection (no receptacle) or a NEMA 6-15 (240V/15A) receptacle.)
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Yes, that is kind of a one-way compatibility thing in electric code. If the circuit is only made for 15A, with the thinner wire and a 15A breaker, then it is only allowed to have the 5-15 outlet types on it. But if it is built as a 20A circuit, with the thicker wire and a 20A outlet, then code does allow putting a mix of either 5-15 or 5-20 outlets on it, as the installer has available.
So following that logic condition, if you see one of the 5-20 outlets on there, you can reasonably know it has to be a 20A circuit behind it. But if it's a 5-15 outlet, that could be either, so you would want to open it up to check the wires and breaker to make sure which size the circuit is.
That tends to get really overblown as a fear because of a few bits of information that end up out of context. So here is some of the breakdown on that:
1. The kernel of truth: The studies about lithium ion battery charging and power rates that show this thing you're talking about are trying to keep extra variables out of the equation. So they are just straight up battery cells without any cooling apparatus. And so the higher charging power heats up the cells a lot more, and it is mainly this high heat while fast charging that causes most of the damage. With Tesla and a lot of other electric cars that monitor and manage the temperature well and have active liquid cooling systems, they can reduce that effect, so it's not much of an issue.
2. The things you may have heard about Tesla cars and batteries specifically were related to the earlier packs in the Model S and X. People refer to this thing called "Chargegate". But I have not seen that this is affecting any of the Model 3 or Y yet, with their newer redesigned cells and packs, so I think they have learned and improved this, so it's less of a factor in the newer cars.
3. It still doesn't "kill" your battery. With the S and X, what people were seeing was that after some amount of DC fast charging (inclusive of Superchargers and/or CHAdeMO) Tesla pushed an update that would cap down the upper limit of the charging speed. That's it. The battery wasn't "killed". It wasn't "dead". It just took longer charging up at Supercharging stops when you were traveling, which did start to annoy some people. I have a 2014 Model S with about 85K miles on it. I may have been capped or may not; I haven't bothered to measure it or check. I just tend to be a laid back, patient person, so I still travel with my car, and it takes however long it takes, and it's not significant enough for me to mind yet.
Black306
Active Member
I’m not either, but I did stay at a Holiday Inn Express last night.
If there is only one outlet (receptacle) on the circuit then the existing 3 wires (hot, neutral and ground) can be repurposed to be (hot, hot and ground.) Some 240V circuits don't use the neutral wire. You won't need to run new wire provided the existing wire is in good condition.
At least one supplier of electric vehicle service equipment (EVSE), ClipperCreek, sells an EVSE for this specific scenario (240V/15A, hard wired):
12A Level 2 EVSE LCS-15 | ClipperCreek
EVSE Adapters sells a NEMA 6-15 power plug adapter for the Tesla Gen2 Mobile Connector: For Tesla Model S, Model 3, Model X, & Model Y Gen 2 – EVSE Adapters
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