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Marina Charging - NEMA L5-30P to NEMA 14-50

LoudMusic

Member
Jul 21, 2020
332
430
Arkansas
My car is going to be spending time in marinas the next several months and it would be nice to charge the car while it's parked there. I have a NEMA 14-50 adapter for my mobile connector, but those plugs are definitely not common at marinas. They typically have the 125v/30A "L5-30R twist lock" outlet and the 125/250v/50A "SS2-50R twist lock" outlet. Unfortunately the 50A outlets are almost exclusively at the far ends of the dock. But often times the 30A outlets are next to or even IN the parking lots. Often times there are NEMA 5-15 outlets around as well, and I've actually used them at marinas before, but that's awful slow.

I'm curious what's the best way to get the most power from the 125v/30A that is available. My first thought is to adapt from NEMA L5-30P to NEMA 14-50 and use my existing Tesla adapter and set the car to the recommended 24A. But does the mobile connector fail if it only gets one leg of the power when the NEMA 14-50 adapter is plugged in? If it does fail on single leg then I'd assume all the others do as well and my biggest possible would be NEMA 5-20, which is an insignificant upgrade from NEMA 5-15.

If it doesn't fail, AC WORKS® [EVL530MS-018] 1.5FT EV Adapter 30A 125V L5-30P Plug to 50A EV Adapter Cord for Tesla

Alternatively, this thing is SO CLOSE but it's an L5-20 not an L5-30. ***flips table*** Which curiously isn't even listed in the standards charts that I'm looking at.


Older Posts (2015, 2013)

Well I typed all that up so I'm posting this new thread. But I also just found this, which didn't come up in a search on their site but did come up in a search on Google.


Problem solved. Have a nice day ;)
 

wws

Member
Aug 11, 2014
931
949
Northern California
On road trips, I always carry a 5-20 UMC adapter. I've used it several times in hotel and motel parking lots instead of the 5-15 UMC adapter. Gives a couple extra mph of overnight charging. If you need L5-20, off the shelf L5-20P to 5-20R adapters are available from any number of places.

For L5-30, it might be a better plan to buy an off the shelf L5-30P to TT-30R adapter - again from any of a number of places. Then buy the TT-30 UMC adapter from evseadapters. (I see they are on backorder right now. But given how popular a product it is, I'd think they'll have more in Real Soon.) The nice thing about TT-30 is that there are quite a number of off-the-shelf extension cords, adapters, and repair parts available at reasonable cost due to its widespread use in the RV community.

If Tesla were to ask me which one additional UMC adapter they should offer, I would easily vote for TT-30.
 

Janus

Member
May 30, 2019
236
164
Bay Area
The nice part of EVSE Adapters is they properly/automatically set the max amperage. That is (IMHO) the best option. Otherwise, you have to manually set/verify the amperage on the MCU before each time you connect. When you're in a shared/public space, you might not have easy access to the breaker panel should you forget or set it incorrectly. (i.e. Often people forget about the 80% rule, and end up with frequent breaker trips; or worse...)
 

mociaf9

Active Member
Oct 18, 2018
2,551
5,167
CA
Well I typed all that up so I'm posting this new thread. But I also just found this, which didn't come up in a search on their site but did come up in a search on Google.

Problem solved. Have a nice day
I agree with wws, unless you're really going to be making regular usage of the L5-30 outlet, in the long run the more useful move would be to buy (or make) a normal L5-30 to TT-30R adapter and then get a TT-30 plug for the Tesla UMC from EVSE Adapters. It would be a bit more expensive as you're paying for 2 items, but you have the added benefit that the TT-30 adapter has waaaay more potential utility because it's such a common outlet type to run into at campgrounds/RV Parks/etc. If I was going to live at the marina and be charging there every day, I would go with the L5-30 UMC adapter alone. But that's the only situation I'd do that for.
 
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LoudMusic

Member
Jul 21, 2020
332
430
Arkansas
I agree with wws, unless you're really going to be making regular usage of the L5-30 outlet, in the long run the more useful move would be to buy (or make) a normal L5-30 to TT-30R adapter and then get a TT-30 plug for the Tesla UMC from EVSE Adapters. It would be a bit more expensive as you're paying for 2 items, but you have the added benefit that the TT-30 adapter has waaaay more potential utility because it's such a common outlet type to run into at campgrounds/RV Parks/etc. If I was going to live at the marina and be charging there every day, I would go with the L5-30 UMC adapter alone. But that's the only situation I'd do that for.

That definitely makes sense, but I also have the NEMA 14-50 UMC adapter, which can be used at nearly as many campgrounds as a TT-30, and to significantly greater advantage.

I think there's also some value in not having to daisy chain adapters. Performance, safety, personal ease of use, and the way other people perceive "EV life" are all improved by eliminating that one part.
 

George I

Member
Oct 24, 2017
46
36
Toronto
While the 14-50 is definitely much faster, the TT-30 is much more common at campgrounds in Ontario. The Ontario Provincial Parks at their electrical sites usually have a 5-15 and a TT-30 but no 14-50. At marinas the L5-30R is also much more common than any other plug. It is best to set up your adapters that the maximum safe current is automatically set so you do not have to remember to turn down you current draw. If you are daisy chaining adapters I suggest turning the current draw down a further ~10-20% than the auto selected maximum. (eg at a L5-30 where you have a daisy chain the max short term draw is 30a, continuous draw is 24a so you set the draw still lower at 20-21a. Yes it s a bit slower but you decrease the chances of overheating etc If you have any worry you may also sleep a little sounder. This is still faster than a 5-15!)
 

LoudMusic

Member
Jul 21, 2020
332
430
Arkansas
While the 14-50 is definitely much faster, the TT-30 is much more common at campgrounds in Ontario. The Ontario Provincial Parks at their electrical sites usually have a 5-15 and a TT-30 but no 14-50. At marinas the L5-30R is also much more common than any other plug. It is best to set up your adapters that the maximum safe current is automatically set so you do not have to remember to turn down you current draw. If you are daisy chaining adapters I suggest turning the current draw down a further ~10-20% than the auto selected maximum. (eg at a L5-30 where you have a daisy chain the max short term draw is 30a, continuous draw is 24a so you set the draw still lower at 20-21a. Yes it s a bit slower but you decrease the chances of overheating etc If you have any worry you may also sleep a little sounder. This is still faster than a 5-15!)

The very limited exposure I have to US campgrounds, city/state/national, the 14-50 has always been available. Maybe we run air conditioners more in our RVs?

I've used my EVSE L5-30 a few times now and it's been great. Charging at 3kw is way better than 0kw or even 1.5kw (which I've done previously for more than a month as my primary).

Unfortunately these additional adapters are kind of expensive, so choosing carefully is probably the best route. And with Supercharger locations becoming so much more common, simply having a trickle charge on 5-15 might be enough and fill up at the nearest Supercharger when needed.
 

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