Y connector to combine 2 campsite 14-50s?

[Ceilidh]

Hey all. I am relatively new to this forum. I tried looking for an answer to this question in the other posts but could not find anyone referring to what I asking about. Forgive me if I just missed it.

The fact that it has not been discussed may mean that this is a silly question, but here goes:

I have seen much discussion about RV site plugs when taking extended trips and how to most effectively use them. Many have rigged special plugs to increase draw and decrease charging time (particularly in the Roadster forums).

One thing I have never seen discussed is trying to simultaneously draw off of 2 RV sites. I am picturing an adapter that splits one NEMA 14-50 plug into 2, and an extension cord to the second plug for situations where the sites are not terribly far apart. Is this worth discussing or just useless?

I don't really recall how my physics 101 relates to these RV plugs in the real world, and I'm trying to figure out creative ways to minimize charge time on longer trips with my Model S when it arrives.

For those interested, it is P912. Supposed to come in November but we will see.

I do realize all the supercharger hype and am looking forward to them. I'm just thinking that although it is often nice to take a break and enjoy nature in the middle of nowhere from time to time, there are other times when you just need to get someplace fast. I would much rather do it on sunlight, or any percentage of something other than gasoline/oil.

Thanks for any thoughts.

 

[Lloyd]

No comment!

 

[mnx]

You should probably post this in the charging section...

A quick search and I found this:

Adapter to combine two 30A level2 into one 60A J1772 - faster charging - Page 2

I've actually built a front-end to a Tesla HPC that mobilizes it in this way, allowing 70A 240V charging. It's a crude approach that checks hot wire polarity (which is often reversed for every other RV slot to balance air conditioning loads), then engages a contactor to connect both 14-50 connector hot wires in parallel. I've got two 100A ammeters to monitor the current split, which usually splits pretty evenly (I'm using 30 feet of cable for each hookup to keep the wire resistance similar). I start at 40A, then step it up to 70A if things look okay. Strangely enough, the RV park operators don't seem to mind if they have open slots - I just tell them it cuts the charge time in half and reduces the odds of popping a breaker.

 

[NEWDL]

The answer is: Unless TESLA makes a cable to do this and tells you that it is meant for your car I would not plug your car into it.

There is no telling what system is behind each of those two plugs.

JB is the only one who would know how to make this work... and he isn't going to tell any of us. ;-)

 

[Ceilidh]

Sorry, I tried to post it in the charging section so I'm not sure how that got messed up.

I very much appreciate the reply. Don't know how the searches I did missed that thread. Thank you!

 

[Eberhard]

if you have the twin charger , then it may be possible, but then the model S needs two charger ports each connecting to a separate charger.

 

[pilotSteve]

if you have the twin charger , than it may be possible, but then the model S needs two charger ports each connecting to a separate charger.

Huh? Its a single charge port, same in any Model-S. The twin chargers are internal to the car and allow the USE of 80A instead of being limited to 40A.

I too would be concerned with a DIY adapter that was not properly engineered and test. The post mentioned by @mnx actually sounds like it could be workable.....

 

[Ceilidh]

I agree that the device proposed on that thread sounds much safer... but of course more difficult to build and heavier to carry in your frunk. Could be worth the time though.

 

[FlasherZ]

If you insist upon doing it, then the post that mnx references it is the best way to perform the kludge. It mentions and addresses the two major issues with paralleling circuits -- the polarity (so you don't create a low-resistance dead short) and the balance across the circuits, which requires similar resistances in both wire paths. Using a contactor (versus the manual breaker method in the pencil drawing below it) is a smart way to do it, and even better if the contactor can be driven by a smaller set of contactors that ensure voltage across P1-A/P2-B and P1-B/P2-A (where P1 = plug 1, A/B is the hot leg), so it's practically impossible to create a dead short. Then all you have to do is monitor for balance.

 

[doug]

Just to avoid confusion. The forum this thread currently is in is specifically for battery and charging options for the Model S. E.g., "Should I install an HPWC?", "Can I use this to charge my Model S?", "Do I get the twin chargers?", "How much time to charge he 60 kWh battery?", etc. The Charging Standards and Infrastructure forum is more general.

 

[jcstp]

apparently it is possible

Twitter / ElectricRdTripS: Made it to CA! Snow has stopped, ...

Made it to CA! Snow has stopped, sun is out and our 80A quick charger is pulling from two RV 14-50's. Things are looking up

but how is it done?

 

[montgom626]

apparently it is possible Twitter / ElectricRdTripS: Made it to CA! Snow has stopped, ... but how is it done?

Very good question. A picture would be nice.

 

[FlasherZ]

Likely an OpenEVSE or a Clipper Creek with two 14-50 plugs, and a quick safety/light interlock to ensure that the legs are properly oriented.

You need to ensure the circuit lengths for both are the same, the legs are proper (so you don't create a dead short), and then you have to signal to the car that 80A is available.

 

[dsm363]

If Clipper Creek sold something like this that was rock solid like their chargers and safe, I'd buy one. Having 80A at every RV park would be amazing. Of course trying to explain to the RV park what you are doing or how much money they want would be a separate issue.

 

[FalconNinetyD]

Sounds like it's a device he made himself. At the end of the blog post:

Today was quite a day. We went from charging on the generally available J1772 Charger at 19 miles/hr to charging on my custom EVSE at 65 miles/hr to charging on a Supercharger at almost 300 miles/hr! What a day!

 

[mitch672]

We had some discussion about how to do this, it basically involves running the (2) 14-50s into your own home brewed electrical panel, to add up to (2) 40A legs on each of the seperate circuits into a 100A subpanel, then to the EVSE, there are many many issues with the design, ranging from burning down the RV Park to electrocution. You need several safety checks on the way, and lots of hutzpa to actually use the contraption (and it IS the very definition of "Rube Goldberg") It would feed into an OpenEVSE device or a Tesla HPWC, then to the car. It's a lot of iron & cabling to drag around with you as well..

 

[bluetinc]

Hey All,

I saw this tread and figured I'd toss up some pics before I manage to get a writeup up on the web site. The short version is that it is a custom EVSE that I designed and built. It has a bunch of processing and safety checks that get preformed on the two inputs to see what it can do with the inputs, takes care of communicating with the car etc, and continues safety checks during charging. I've found all of the RV parks to be very happy to let me use two 14-50R's, and all but one have been usable for my system. Here are a few pics of one of the easier hookups with two 14-50R's on the same post

Peter

 

[efusco]

Hey All,

I saw this tread and figured I'd toss up some pics before I manage to get a writeup up on the web site. The short version is that it is a custom EVSE that I designed and built. It has a bunch of processing and safety checks that get preformed on the two inputs to see what it can do with the inputs, takes care of communicating with the car etc, and continues safety checks during charging. I've found all of the RV parks to be very happy to let me use two 14-50R's, and all but one have been usable for my system. Here are a few pics of one of the easier hookups with two 14-50R's on the same post

Peter

View attachment 13923View attachment 13924View attachment 13925

Any chance you'd share the design details?


Evan, Via Tapatalk

 

[unclfuzzy]

Any chance you'd share the design details?


Evan, Via Tapatalk

Better yet, give us a price on a built one.

 

[JohnQ]

Please don't give me any incentive to change my config to include twin chargers! :tongue: