Charging from 14-50 at 50A?

[bluetinc]

Hi all,

I'm working on some trip planning and I'm curious about squeezing a little more out of charging at a 14-50 outlet. From what I have read, as long as you are charging for under 3 hours, the NEC doesn't consider you a continuous load, and drawing up to 100% of the breaker rating is permissible (vs. an 80% limit of rating for continuous loads). This seems to imply that I could bump my charging rate up from 40A to 50A at RV parks etc. if I am just stopping in for a couple hour charge.

So, code books aside, I wanted to find out if others have done or do this and how well it has worked?

Thanks!

Peter

[donauker]

Hi all,

I'm working on some trip planning and I'm curious about squeezing a little more out of charging at a 14-50 outlet. From what I have read, as long as you are charging for under 3 hours, the NEC doesn't consider you a continuous load, and drawing up to 100% of the breaker rating is permissible (vs. an 80% limit of rating for continuous loads). This seems to imply that I could bump my charging rate up from 40A to 50A at RV parks etc. if I am just stopping in for a couple hour charge.

So, code books aside, I wanted to find out if others have done or do this and how well it has worked?

Thanks!

Peter

I have successfully pushed new breakers to 100% without a problem, but many campground breakers are weathered and also worn from being used as switches. I have had several campground 50 amp breakers that tripped occasionally at 40 amps and there was even one that wouldn't reliably handle 32 amps.

[doug]

Probably not that big of a deal if you're there to watch it or are using something like OVMS/Tattler to alert you if the breaker trips.

What charge connector are you using? Are you able to hack the pilot signal?

[bluetinc]

Doug,

Unfortunately this is all in my mind so far.. I'm planning on picking up my S in October out on the west coast, and doing a fun road trip back home (MD) (read 4500 miles). I've been refining my trip plan, and time needed to charge each day (especially for the mid day charges) and I'm trying to figure out if pulling the full 50A is realistic to include in my plan.

Peter

[doug]

Oh? I thought you were talking about the Roadster since this thread is in the Roadster forum. If you're talking about using the Model S, you are unlikely to be able to get more than 40A from UMC that comes with your Model S. Also I don't think you'll be able to convince the Model S to ignore the pilot signal and pull 50A instead of 40A.

You'd need a custom NEMA 14-50 EVSE where you can manually set the pilot signal. You can probably buy or make one that goes 14-50 to J1772, and then use the J1772 adapter that Tesla has promised to provide.

[Doug_G]

NEC says "continuous" is > 3 hours? I don't really understand that. I'm sure the temperature of the components after 100 hours will be no different than after 3 hours.

[bluetinc]

Doug,

I figured that any real world experiences with this would only be over here with Roadster owners, and all I would get in the S forum would be guesses.

I'll have to look into the max on the UMC for the S, and overriding the Pilot signal. As you suggest going through the J1772 adapter may be necessary. I guess the other option would be to kludge an adapter that goes from 14-50 to the HPWC, and then to the S...

I thought that somewhere along the way, but quite some time ago, I had seen a screen in the Roadster (or maybe an S prototype) that allowed someone to override the default current limits when charging. Perhaps I didn't understand quite what I was seeing?

Doug_G, I don't know why they chose 3 rather than 1 or two...

Peter

[donauker]

Peter,

You can only override the pilot signal with a lower value. You would need a charge connector that provided a higher current pilot signal such as a DIY unit or a HPWC with a 14-50 plug.

Don

[vfx]

Another "Can I make it"? topic. Maybe it needs a section?

[TEG]

Along with worn breakers, I have heard that many NEMA14-50s at campgrounds have physically worn sockets that can overheat just due to marginal connection between the plug and socket. So, campgrounds are probably one of the worst places to try pushing max current through the connector. Are you going to sit and watch it the whole time to make sure nothing melts or catches fire? Some (but not all) EVSEs include temp sensors in the 14-50 plug to detect high temps and reduce the level if that happens.


Slightly related:
Why Did My R.V. Adapter Plug Melt? My 125V 30A to 125V 15A got very hot. : Electrical Online
Milbank RV 50amp receptacles melting