Towing and charging

[Luke42]

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.

I don't see any theoretical reason why charging and ePTO modes should be mutually exclusive.

Pulling power from the ePTO (the HVDC bus) should slow down the battery charging (just like pre-conditioning the interior & battery), but that's a reasonable tradeoff to make.

However, I'm accustomed to vehicles being locked down, secured, and non-functional when unattended and when the key is removed. The stop/acc/run/start state-machine on most cars wouldn't accommodate this use-case, and changing it on a conventional vehicle is harder than it looks.

However, Teslas handle this state machine differently, because they don't use a physical key with physical detents. They've already added other run-modes to the vehicle (like "camping mode"). So, they should be able to add a "parked & charging with ePTO enabled" mode.

I just haven't seen any indication one way or another about whether they plan to do this. It would be fairly easy to make a medium-level engineering decision which would prevent the "parked & charging with ePTO enabled" mode from working -- as the ignition switch does in a conventional ICE vehicle. I don't see any fundamental or theoretical reason why it wouldn't work in a Tesla, though.

I would put "parked with ePTO enabled" to good use, both while charging and while boondocking.

Will Tesla implement this feature? I sure hope so!

 

[Luke42]

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.

I keep hoping the Cybertruck has a multi-voltage DC charging port that could slow-charge the big battery.

When I was shopping for my travel trailer, I saw a TT with a nice weatherproof PV DC charging port on it. (The connector was 2-pole, the pins looked to be in the 15-20 amps-ish to my eye, and it had a screw-type round locking connector over the whole thing.) I didn't catch the DC input range or amperage limitations, because the only thing I liked about that one was the price... I liked the port, though! I'd be just as happy with the Zamp connector, or a right-sized Anderson connector.

A DC charging port would need to have a wide-range of input voltages so that it can charge the truck from a wide variety of DC power sources -- kind of like an MPPT solar charge controller.

I'd love to see something like that on the Cybertruck.

However, early in the production ramp-up is the time for KISS engineering -- rather than feature-bloat.

 

[Hunter71294]

Whenever the Tesla Semis start hitting the roads there should be charging ports at truck stops. Assuming they're the same connector. The semis will have a giant battery pack and most will still be local delivery trucks, so it could take a while for these to be common even if they're the same.

 

[Luke42]

Whenever the Tesla Semis start hitting the roads there should be charging ports at truck stops. Assuming they're the same connector. The semis will have a giant battery pack and most will still be local delivery trucks, so it could take a while for these to be common even if they're the same.

That would be great. However, there are two problems:

• The Semi charging port looks to be about 4x bigger than the car charging port. It's likely that the CT will use the car charging port.
• Many RV campsites can provide 12kW (240V @ 50A) to the standardized electrical pylon.

When pulling my travel trailer with my ICE truck, a full travel-day requires 2-3 fuel stops (the CT3 ought to have roughly the same range as my ICE truck -- my ICE truck suffers a 50% range-reduction when towing). I'd love to eliminate one of those stops by charging at the campground and leaving with a full battery in the morning.

Supercharging around lunchtime on a travel day would still be worthwhile -- but why supercharge twice, when you can L2 charge overnight at a KOA?

Boondocking is a different use-case. Probably want to supercharge close to the campsite, and then again after leaving the campsite.

 

[ajdelange]

I keep hoping the Cybertruck has a multi-voltage DC charging port that could slow-charge the big battery.

What I am hoping for is that that port (or ports - I'd like to see several) are for PV panels i.e. mate with typical PV connectors and have MPPT controllers behind them.

 

[jhogan2424]

What I am hoping for is that that port (or ports - I'd like to see several) are for PV panels i.e. mate with typical PV connectors and have MPPT controllers behind them.

Yes! This would lead to a lot of creative folks coming up with different solar designs. It would be so cool to have a built in MPPT with a simple + and - MC4 or similar plug that would accept a decent range of DC voltage and amps. This would be one of the coolest features for a CT in my opinion. Not particularly useful everyday, but definitely a major cool factor.

 

[ajdelange]

I don't see any theoretical reason why charging and ePTO modes should be mutually exclusive.

For the outlets to be useful they clearly have to be capable of being enabled when the truck is in park and the driver is away just as dog mode needs to be. Just as dog mode needs to work when the car is plugged in so must the outlets continue to be active when the truck is plugged in. OTOH you don't want any itinerant potter to be able to approach your truck and plug in his kiln. So I expect that, similar to dog mode, you will be able to enable or disable the outlets from the main screen and the app irrespective of whether the charger is plugged in.

 

[Dave Lyon]

. 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.

The inverter in the truck will not be large enough to power a house. Only a few critical circuits like your fridge or freezer.

You'd also lose quite a bit to conversion drains. You'd be better off to switch between having your solar charge your EV, and when done charge your house batteries or switch to grid tied.

 

[kev12345]

they'll have to start building pull thru's for the trucks. unhooking to charge will get old fast. unfortunately elon seems more concerned with gimmicks like yokes, no door handles and 0-60 times rather than actual truck stuff at the moment.

 

[firsttruck]

they'll have to start building pull thru's for the trucks. unhooking to charge will get old fast. unfortunately elon seems more concerned with gimmicks like yokes, no door handles and 0-60 times rather than actual truck stuff at the moment.

The Cybertruck announced in 2019 was better than ICE F-150.

Cybertruck announced in 2019 is better than Ford announced 2022 F-150 Lightning.

Still Elon then adds rear wheel steering to Cybertruck.

Cybertruck has a ton of relevant truck features.

 

[ajdelange]

The inverter in the truck will not be large enough to power a house. Only a few critical circuits like your fridge or freezer.

The CT inverter will be 30A at 240V. That's 7.2 kW. I have a largish house and pulled, on average over the last month, 3.7 kW. The average American house uses 30 kWh per day. That's an average of 1.25 kW. And the truck will have a 200 kWh battery so it would last the average guy 6 days (and me more like 2). So clearly no problem with the inverter size as long as the peak loads are controlled (big ones shed). Lots of people install transfer switches and use 5 - 7 kW generators for emergency power. The CT is eqivalent, in terms of power deliverable to a house, to one of those.

You'd also lose quite a bit to conversion drains.

Not really. Today's inverters are better than 90% efficient.

You'd be better off to switch between having your solar charge your EV, and when done charge your house batteries or switch to grid tied.

You missed the point. It is that the CT is potentially quite flexible in terms of what one can do with it as a load leveler. Unless Tesla does something to prevent or make it difficult to use it as such.

 

[Dave Lyon]

The CT inverter will be 30A at 240V. That's 7.2 kW.

While that's impressive, it won't handle most houses. A water heater would use half that, and a central air conditioner would use almost all of it. You wouldn't be able to use them both at the same time. Much less any of the other loads a typical house has.

 

[Crissa]

The inverter in the truck will not be large enough to power a house. Only a few critical circuits like your fridge or freezer.

I can power my house on a 50a drop,

-Crissa

(Of course, I don't have A/C and you can just turn it off while you take a hot shower.)

 

[ajdelange]

While that's impressive, it won't handle most houses. A water heater would use half that, and a central air conditioner would use almost all of it. You wouldn't be able to use them both at the same time. Much less any of the other loads a typical house has.

I don't know where you are getting these ideas but as I mentioned in my last post I averaged 3.64 kW over the last 6 months which is 87.6 kWh/da, almost triple what the average US house takes. Median draw was 2.8 kW. I exceeded 7 kW 10.6% of the time. My baseline load was 1.65 kW. Given that power consumption (or at least mine anyway) is baseline plus a Weibul distributed random load it is pretty easy to suppose that the average house might have a baseline 1/3 what I do and that the difference between the median and baseline might be 1/3 of what it is for me. With those assumptions its easy to estimate that the probability of exceeding 7 kW is 1E-5 (0.001%). In a year it would be exceeded 5 minutes. For me it would be 929 hours so I wouldn't even try to run my whole house on the CT or a 7 kW generator. Now I would not hesitate to put 40 or 50 amps of loads on one of those priority circuit transfer panels they sell for this application with small generators. Their ubiquity should be sufficient evidence that you can indeed do what you are saying you can't do. Millions of people do it. Intelligent load shedding is, of course, part of this. Assuming it's a power emergency that has caused you to hook up your house to your CT you tell Mrs not to bake cookies in her electric over, fire her most recent pottery project of dry clothes until the power is back on. Not only does this protect the gnerator/inverter from overload but it makes the fuel/charge last longer. If you are hooked up legally no load of that magnitude is on the transfer panel. It is only connected to refrigerators, lights, communications, the well pump etc.

I said above that I wouldn't try to run my whole house on a 7 kW generator. In fact I used to do exactly that during power outages and what a PITA that was. But we could run the heat, the A/C, the well, watch TV etc but had to manage the load. Eventually I put in a bigger generator. It has automatic load shedding but AFAIK it has never triggered (IOW the generator I bought is too big).

 

[Dave Lyon]

I don't know where you are getting these ideas but as I mentioned in my last post I averaged 3.64 kW over the last 6 months which is 87.6 kWh/da, almost triple what the average US house takes. Median draw was 2.8 kW.

I get these crazy ideas by using math. Average loads really aren't relevant. Peak loads will exceed what the CT can supply. As I said, a central AC unit will use almost all the power it can supply. If the water heater kicks on at the same time, it's not going to be able to handle the load.

Sure, you could run it to a box that handles only the most important loads during an emergency, but that's not what we were talking about.