Towing and charging

Luftpilot

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I am wondering, when pulling my 37 ft travel trailer and need to pull in to a charging station, do I have to unhook my CT? I can hardly imagine, having the CT and trailer sitting at a charging station for an extended amount of time.
Unless, Tesla is designing some "trailer friendly" stations, meaning, I can leave my trailer hooked to the CT while charging. That, of course, would be ideal. Your thoughts, please...

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Dave Lyon

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If your camper is just 30 amps, you might be able to plug it into the CT, and plug the CT into the 50 amp pedestal.

Some campgrounds aren't wired properly and may take one leg from the 50 amp plug to run the 30 amp. Their thinking is nobody would try to use both of them at the same time.

I intend to do something similar. My camper is 50 amp, so I'll plug it into the pedestal. I have a 14 kwh battery pack and dual inverters that will turn on an auxiliary charge port when the batteries are over a certain percentage, so I'll plug the CT into it. I might be able to do a small charge from solar if I add some panels. :)
 

Crissa

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It's just like how outlets in your home are wired: Each outlet has two sockets, each socket capable of 15a but you have two on this wall and two on that. The idea being that you don't use more than the 15a at any time, even though multiple devices are plugged in.

-Crissa
 

Dave Lyon

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I custom built mine from individual cells. It's much cheaper that way.

I'm using twin Victron 3000 watt inverters so I can run everything in my camper, including both ACs. They already take care of all the load sharing and routing, so it makes it pretty easy.

I'm not an engineer, but I play one at work, so I found the studying and math required to build the system fun. :)
 


RandyS

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It's just like how outlets in your home are wired: Each outlet has two sockets, each socket capable of 15a but you have two on this wall and two on that. The idea being that you don't use more than the 15a at any time, even though multiple devices are plugged in.

-Crissa
Crissa, It is true that a single 15 amp circuit in a home will have multiple receptacles on it, light switches, etc. spanning a couple of rooms...It's really up to the user not to plug in too many things and trip the breaker. It usually works pretty well since lighting is getting more efficient with LEDs, etc. and TVs take less energy than they did before. But you just have to be conscious of not plugging in too many items...
 

Crissa

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The idea of the breaker is to just not overload the wire leading to the socket, and the socket's design tells you what the maximum is - but doesn't tell you if anything else shares it.

-Crissa
 

ajdelange

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I can't see any reason why you shouldn't be able to do this. In fact I do it now with a Yeti battery pack that is "running" the garage I am having built while I wait (and wait and wait ....) for Powerwalls to be delivered. It's charger, which charges it at 180W, is always plugged into an extension cord running from the house but if the workmen need to turn on the lights, open the garage door or even operate the heat pumps to test them they are supplied by the inverter.

As is the case in my present application the charger/inverter isolates the truck bed outlets from the mains feeding the charger. A big potential plus if this is allowed is being able to run up to a 7 kW 240V appliance from a 1 kW 120V camp generator as long as you only run it intermittently.


There are a couple of places in the code where similar things are done. You can put lots of 15A outlets on a 15A feeder. You can put a thousand pole ampere's worth of breakers in a 200A (400 pole amp) panel.



Or that the sum drawn from them won't exceed 50A on either phase (the 30A campground outlet is 120V)


But you can't plug in a full 50A charger because there is no (legal) charger that can be plugged in that will feed that much to a BEV. The max is 40A and the UMC that comes with Tesla vehicles currently with its 14-50R adapter only takes 32. Thus you have, charging at the max rate, 10 - 18 A left over for the TT30


That's what it comes down to. You can set the charge level in the car to 20A so that the full 30 is available to the TT30. You can also reason that if you charge for less than 3 hrs the load isn't persistent even though the code says it is, unplug the trailer, plug in a 50A charger and take the whole 50A for the truck. But if you plug the Tesla UMC into the 14-50 and your trailer into the TT30 and are mindful that you only have 18A for the trailer you should be fine. And if you want to use more than that in the trailer you can go out to the truck and turn the charge rate down. Big gripe of mine is that you have to go out to the truck to do that because you cannot do that via the app. Fix it!

People towing rigs with 14-50R plugs have a more interesting situation.
 
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firsttruck

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I custom built mine from individual cells. It's much cheaper that way.
Interesting.

What type of cells (chemistry, format, KwH)?

Did you buy from USA supplier or did you need to order direct from China?
 

ajdelange

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If your camper is just 30 amps, you might be able to plug it into the CT, and plug the CT into the 50 amp pedestal.
This brings to mind a very (IMO) interesting question. If you can do this with a trailer you can do it with your house (with proper transfer switch). You could, for example, hook up some solar panels to an inverter and use the inverter to charge the truck but run the house from the truck inverter. This kluge replaces the functionality of a Powerwall (or similar product) with the truck. The question is as to what Tesla's position on this will be WRT warranty. It is certainly going to stress the truck's battery beyond what it would experience in normal driving.
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