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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Luke42

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This has been discussed quite a bit on this board. We don't know for sure, but the group's best guess is that, since the Supercharger network is constantly being expanded, that Tesla will provide some trailer-friendly spots in the near future.

I pull a 20' TT with a hybrid pick up. What I'm really looking forward to is charging an EV-truck at campgrounds. My TT uses a 30A @ 120V power source so, if I get a 50A @ 220V campsite, I ought to be able to charge overnight (with some care to make sure I keep the load below 50A on both legs). The charging amperage is adjustable on the truck side.

Leaving camp with a full battery every morning will cut out a lot of fuel stops -- unless I'm boondocking, of course.
 
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Luke42

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Seems like you'd need to unhook that in most gas stations.
Refueling is an art when you're towing a travel trailer.

When I'm driving, my wife will look ahead using satellite photos on Google Maps to make sure the gas station layout looks trailer-friendly.

If she doesn't do that, I use my aviation-mindset and have an out (a plan for a go-around in this case) if the gas station doesn't look friendly to my 45' long combination vehicle.

That and the MPG hit which comes with towing are are things that people who tow with gas/diesel vehicles just accept with minimal complaints. Not because these things don't suck, but because they've always been that way -- so it's the driver's problem.
 
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Dave Lyon

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I pull a 20' TT with a hybrid pick up. What I'm really looking forward to is charging an EV-truck at campgrounds. My TT uses a 30A @ 120V power source so, if I get a 50A @ 220V campsite, I ought to be able to charge overnight (with some care to make sure I keep the load below 50A on both legs). The charging amperage is adjustable on the truck side.

Leaving camp with a full battery every morning will cut out a lot of fuel stops -- unless I'm boondocking, of course.
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. :)
 

Luke42

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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.
:)
I hope running the inverter and charger at the same time will be an option on the Cybertruck. That would certainly make all of the questions go away.

I don't yet have any information to suggest that this is possible.

Being able to charge the truck and use the inverter (ePTO?) would make things easy and safe for those without EE-skills.

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 went as far as to read a bunch of electrician-educators who interpreted the NEC sections about campground wiring.

The wiring going to the campsite is only required by be able to carry 50A (with breakers to match), even for pedestals with 50A, 30A, and 20A outlets. The assumption that you will only use one outlet is baked in to the NEC.

I'd go as far as to say that almost all campgrounds are wired based on the assumption that the 50A and 30A outlets will not be used at the same time.

It's also assumed that the full 50A load will only be used intermittently, especially at larger campgrounds.

Plugging in a full 50A EV charger + a 30A TT (mine is 30A) really should start tripping breakers when the devices pull the full load -- because one leg could pull as much as 80A.

It's really on me to manage the load to keep it below that 50A limit.

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.
Nice!

I've done some paper designs of something close to that 14kWh battery pack, but haven't bought parts or built it yet. (I have a relevant engineering background -- so my electrical/fire safety is my responsibility.)

I've also been considering the Delta Pro portable battery pack (it has a 30A RV plug).

Is your battery pack (partially) custom built? Or is there a commercial unit I haven't encountered yet?

P.S. My wife and I both assume that campgrounds will eventually start adding an EV surcharge for those who tow with electric trucks. I'll be happy to pay it when that happens, assuming it's somewhat related to the campground's cost. I'm fine with them billing me for an extra 180kWh of electricity just because I brought an EV -- I just don't want to be price-gouged. With the marginal cost of electricity being $0.07/kWh at home, an extra $20 tacked on to my stay would be reasonable, because I'm likely to arrive with an empty battery and leave with a full battery.
 
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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
 

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Is your battery pack (partially) custom built? Or is there a commercial unit I haven't encountered yet?
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
 
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Luftpilot

Luftpilot

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ajdelange

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I hope running the inverter and charger at the same time will be an option on the Cybertruck. That would certainly make all of the questions go away.

I don't yet have any information to suggest that this is possible.
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.

Being able to charge the truck and use the inverter (ePTO?) would make things easy and safe for those without EE-skills.
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.


The wiring going to the campsite is only required by be able to carry 50A (with breakers to match), even for pedestals with 50A, 30A, and 20A outlets. The assumption that you will only use one outlet is baked in to the NEC.
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.



I'd go as far as to say that almost all campgrounds are wired based on the assumption that the 50A and 30A outlets will not be used at the same time.
Or that the sum drawn from them won't exceed 50A on either phase (the 30A campground outlet is 120V)


Plugging in a full 50A EV charger + a 30A TT (mine is 30A) really should start tripping breakers when the devices pull the full load -- because one leg could pull as much as 80A.
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


It's really on me to manage the load to keep it below that 50A limit.
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?
 

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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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