It does care about one thing, though - one of the legs (I forget which at the moment) cannot be 0V relative to ground, or you get a red light. So when you feed it 120V, neutral must be on the correct leg (the one the UMC doesn't care about).
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Charging at Campgrounds and RV Parks
- Thread starter doug
- Start date
It does care about one thing, though - one of the legs (I forget which at the moment) cannot be 0V relative to ground, or you get a red light. So when you feed it 120V, neutral must be on the correct leg (the one the UMC doesn't care about).
tomsax
Member
That's the key observation on this issue. Each adapter is designed for a specific type of of outlet, which implies a safe charging limit, and that charging limit is communicated to the car.
If you break that assumption by using an adapter which changes what you are plugging into, or if you plug into an outlet that isn't wired to the expected circuit capacity, it's your job to set the proper charge limit manually or risk anything from popping the breaker, to ruining hardware, to starting a fire.
The safe charging limit is 80% of the breaker's rating.
15A breaker -> 12A charging
20A breaker -> 16A charging
30A breaker -> 24A charging
40A breaker -> 32A charging
50A breaker -> 40A charging
Outlets at RV parks are often old and may not hold up to even the 80% limit. It's important to monitor the charging for at least 30 minutes and if the plug or outlet get hot, lower the charge limit.
At almost every RV park I've been to, a 50 amp receptacle is really only good for around 32 amps, and sometimes not even that. At 40 amps the breaker trips in just a few minutes.
It really depends on how long the park has been there and how many times that outlet has been used. If the park is fairly new I will try it at 40 amps and then check back after an hour to make sure everything is still working OK. If the park and the outlets look really old then dialing it back to 32 amps is probably a good thing to do. Even at 30 amps it will fully charge by morning anyhow.
Bugeater
Member
I've had much better luck than you then Jerry33! I've only had a couple out of dozens that didn't handle 40 amps all night.
tomsax
Member
That may be, but it's awfully unpleasant to wake up in the morning to discover that the breaker popped 5 minutes after you plugged in. That's why I recommended monitoring for 20 or 30 minutes to make sure it's not going to overheat or pop the breaker.
Bugeater
Member
Yea, fortunately for me whenever I didn't have good network connection to the car I never had a problem. Really only once did I have a real issue with the breaker popping. Then I remembered that the circuit was 30 amps and lowered the rate accordingly. There was one RV park that had only 120V 30A service. I didn't have the right plug for it so didn't get to charge that night. Luckily there was a place with 240V 50A service I was able to get to the next day.
Traveling is so much simpler now with superchargers!!!
scottf200
Well-Known Member
Found a good doc on this as well.
Source: http://www.myrv.us/Imgs/PDF/30-amp Service.pdf
Image: http://i.imgur.com/lL5etuc.png
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haven't tried it but this looks interesting: I came across a campground recently that only had TT-30 sockets: AC Connectors EVSE RV/ Generator TT-30 Power to 50-Amp Electric Vehicle Adapter for Tesla - - Amazon.com
tomsax
Member
The Tesla UMC works just fine on a 120V outlet using the proper adapter. It should therefore work with a TT-30. Someone told me they had done this recently, perhaps @DaveD.
If you use the adapter mentioned above that makes a TT-30 look like a NEMA 14-50, then plug in the UMC with the NEMA 14-50 plug, you've told a lie to the UMC. The UMC (and therefore your car) thinks it can draw 40A from a 50A circuit, so you'll have to manually dial down the charge limit to 24A (the maximum allowed on a 30A circuit) BEFORE you start charging.
120V/24A is twice as much power and thus more than twice the charging speed compared to a standard 120V/15A outlet. A NEMA 14-50 is generally 200V to 240V at 40A charging, so lots faster than a TT-30, but no help if you're stuck in an RV park that only has TT-30s.
I'm sure it's been said before on this thread, probably by me, but in the US if an RV park says it has "30 amp service" they mean TT-30, so 120V/30A. If they have "50 amp service" they mean 240V/50A, a much more significant improvement than 30 vs 50 would suggest. So if you're choosing an RV park, go for 50 amp service. If the RV park chooses you, use what they have.
One last note: I believe RVs don't use the 240V part of the NEMA 14-50; instead they use it as two separate 120V circuits. That means an EV park can get away with wiring a NEMA 14-50 so that it uses the same phase on both legs. That works great for running 2 air conditioners in an RV but it yields zero volts and no charging across the two hot conductors. I've seen this in action. Cathy and I spent an hour one afternoon testing every NEMA 14-50 outlet in an RV park looking for one that was wired correctly. Power Tip: keep a volt meter in your [t|f]runk if you're exploring out in the boonies away from civilization and Superchargers.
If you use the adapter mentioned above that makes a TT-30 look like a NEMA 14-50, then plug in the UMC with the NEMA 14-50 plug, you've told a lie to the UMC. The UMC (and therefore your car) thinks it can draw 40A from a 50A circuit, so you'll have to manually dial down the charge limit to 24A (the maximum allowed on a 30A circuit) BEFORE you start charging.
120V/24A is twice as much power and thus more than twice the charging speed compared to a standard 120V/15A outlet. A NEMA 14-50 is generally 200V to 240V at 40A charging, so lots faster than a TT-30, but no help if you're stuck in an RV park that only has TT-30s.
I'm sure it's been said before on this thread, probably by me, but in the US if an RV park says it has "30 amp service" they mean TT-30, so 120V/30A. If they have "50 amp service" they mean 240V/50A, a much more significant improvement than 30 vs 50 would suggest. So if you're choosing an RV park, go for 50 amp service. If the RV park chooses you, use what they have.
One last note: I believe RVs don't use the 240V part of the NEMA 14-50; instead they use it as two separate 120V circuits. That means an EV park can get away with wiring a NEMA 14-50 so that it uses the same phase on both legs. That works great for running 2 air conditioners in an RV but it yields zero volts and no charging across the two hot conductors. I've seen this in action. Cathy and I spent an hour one afternoon testing every NEMA 14-50 outlet in an RV park looking for one that was wired correctly. Power Tip: keep a volt meter in your [t|f]runk if you're exploring out in the boonies away from civilization and Superchargers.
Apparently you didn't bother to click or read the link, where it says it is an adapter made and wired specifically for an EV/Tesla charging system, not like the normal camping adapters.
No, that's really not true. The large mobile homes definitely do use 240V connections--that's why they have those outlets. They are using real air conditioners on high voltage and maybe other systems (water heaters?) that use high voltage. I don't doubt your particular story about how you found one particular RV park that had their outlets wired that way, because I'm not going to disbelieve what you actually experienced. But you are assuming all (or most) parks are done that way, and that is definitely wrong. It is not normal or allowed, and someone would have to check hundreds of parks all around the country to ever find one with that kind of screwed up wiring.
I don't quite care for the bulkiness of having so much torque hanging off the outlet like that, so I prefer the style with the longer pigtail cord offered by EVSEadapters. Look at the one with the longer black cord.
NEMA 14-50R to TT-30P Adapter for EV Charging at Campgrounds
tomsax
Member
I'm not assuming all or most RV parks have outlets wired this way. That's not what I said. In fact, I've found the opposite. I haven't tried hundreds of RV parks, more like a dozen, and only had this experience at one park. The manager had no idea the outlets were wired wrong. Read about RVs with dual 120V air conditioners. The point of my story was just that's it's handy to have a volt meter, which makes testing outlets much easier than moving the car and plugging in the charge cord to see if it works.
OK, perhaps I was getting ahead of myself in not really knowing how big mobile homes are wired. So I guess you are saying they use only 120V systems, but are supposed to have two different phases so it can divide the heavy loads? That wouldn't seem to make much sense, since they have to share the same neutral.
I don't doubt your experience. I'm just perplexed as to how and why this would be wired to get this result. The electrical connections would have to have been intentionally wired this way by someone with no knowledge of electrical work, then inspected by an idiot. Granted, some rural areas don't have inspections.
Anyway, thanks for pointing out a possible problem -- definitely would be a problem in charging a Tesla!
Oh sorry about that... Yeah, I can see this is a "special" adapter:
3750W max = ~120v x 30amps.
The description of the Amazon listing says "to 50-Amp" which could confuse some people expecting to pull 50-amps from that.
As has been mentioned before, "RV speak" includes calling all NEMA14-50 sockets as "50 amp" even if they aren't able to provide that current level.
They may have wired it so it is 120v across to two outside pins (which are usually 240V on a NEMA14-50. The Tesla UMC has a universal power supply that would adjust and I also think dial back the current based on it being 120V not 240V.
It says "electric vehicle use only" and I suspect that is important to follow. If you plugged some other NEMA14-50 device into that adapter it could try to draw much higher current and blow out the breaker on the TT-30 socket quickly.
It might also cause 240V equipment to act weird if it didn't have a universal power supply on it. So, yeah, only use that adapter as intended for a special case. I would call it a "hack", but it does serve a purpose.
Back to the comment that some RVs need/want/expect 240V from a 14-50 socket. I could imagine it is true, but they could then end up limiting their choices of camp sites. Many trailers and RVs I have seen just use 120V appliances inside and only use the 120V "neutral to leg" sections of the NEMA14-50. That way they can still operate if the camp site has only one leg hooked up, or both legs are from the same circuit so trying to pull from both legs gets you 0 volts.
Add to this that many old campgrounds, including lots and lots on the east coast, only provide TT-30 ("30 amp") and no NEMA 14-50 ("50 amp") so your 240V RV appliances would be SOL unless you ran your generator.
For that adapter, between the half voltage (120V not 240V) and partial current (30amp not 40+) your charge rate is going to be rather slow. But if it is for overnight camping maybe that is fine. I just wouldn't want to depend on that adapter for "while you wait" type road trip charging... Too slow.
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