Propane Generator Option For Longer Trips

ajdelange

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Let's begin by assuming that the trip is equivalent to EPA driving. The Dual has an EPA range of 300 miles (IIRC, if I don't just put in the right number). In such a case you would use 20/300 = 6.7% of the battery were you a better than average driver. Accumulated data on the other models indicate that most people achieve about 85% of EPA range so you might expect to use 20/(0.85*300) = 7.8% of the battery. But you are hardly under EPA conditions going up a mountain off road. Your actual consumption can vary all over the place. Being really pessimistic it could treble. In such a case your battery use would be 3*7.8 = 23.4% of the battery. Under less demanding conditions it might only double to 15.6%. And if the "trail" is a hard packed dirt road the increased demand could be a factor less than 2. In planning such a trip initially I would plan for as much as a quarter of the capacity being used and when I got to the trail head would set one of the trip odometers and record the actual consumption for a more accurate plan on subsequent visits.


It really is that simple and I expect you might be a little disappointed. So let's now burrow in a bit deeper. Let's assume the CT weighs 3000 kg. The elevation change is 2660' and there are (12*2.54/100) meters in a foot. The acceleration due to gravity is 1g = 9.8 m/sec/sec and there are 3600 seconds in an hour. To haul that mass up that high requires
3000*2660*(12*2.54/100)*9.8/3600 = 6621.27 Watt hours of energy which must come from the battery. Again, IIRC, the Dual CT is expected to have a 100 kWh battery and again, if you have another number in mind use that. Thus just the change in elevation will use 6.6% of the battery. But, in theory, you get that back when you go down the mountain. But you don't get it all back. Perhaps 75 % of it so of the 6.6 kWh (6.6%) you would only actually lose 6.6/4 = 1.65% to the elevation change. Unfortunately, the gravitational component of the energy requirement is the only one for which we can make good estimates. Most of the extra loss comes from the wheels. Experience is really your best guide with respect to those losses. You will gain that if you are observant. A tool like TeslaFi will do all your logging for you if you are willing to pay the fee (modest) and are not one of the nutters who is upset that some Swedish guy has a record of where you have driven and plans to sell it to the CIA.

Now I have a question. What is it with propane? I certainly wouldn't consider hauling propane bottles up a mountain in the bed of my truck and PLEASE don't ever even think about putting one of those in the cab. My sister had (note past tense) a friend that did that. I had a 30 lb CO2 siphon bottle valve fail on me in the bed of my pickup a block from Roberts. Were I to buy a portable generator for this purpose I might well buy a dual fuel (so I could hook it to my bulk tank at home) but would use a Jerry can and gasoline for any trips.

 
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ajdelange

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Anything is possible, of course, but should Telsa have a battery with 20% more energy density than they thought they would have...
I am sure many of you who saw the Panasonic announcement of yesterday must be thinking I am some sort of clairvoyant. I assure you that is not the case. It is pure coincidence.
 

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Great insights and you guys are very good at math, I will give you that! So good at math that I have a new challenge for you. So here's my challenge to you, should you choose to accept: What is your best educated guess of the battery depletion of a Dual Motor CT, that will go a distance of 20 miles of moderate off-roading, with an elevation gain of 2,660 feet? So 10 miles up (to reach 2,660 ft) and 10 miles back down. Go! :) (This is based off of one of my local trails called Stony Pass in Silverton, CO) From these details, I will be able to put into perspective the CT's off-roading capabilities in some realistic environments. From here, we can maybe calculate what a full day of off-roading would look like and see at what point would we might consider carrying a generator and some propane tanks in a real-life situation ;)
I'm no mathlete but my quick math with the assumption that the CT3 houses a 200 kWh battery that gets exactly 500 miles on a full charge means it uses about .4 kWh per mile under ideal conditions. So if we also assume your efficiency off road is going to suck, then lets say you use double that, so .8 kWh per mile. That comes out to 25 kWhs for your 20 mile round trip (20 / 0.8). At least that's the way this simpleton would do the math. No idea how much charge is used going downhill vs uphill. For a direct comparison to aj's numbers...this comes out to 12.5% of the battery. (25 / 200 = 0.125)
 
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SpaceYooper

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I am sure many of you who saw the Panasonic announcement of yesterday must be thinking I am some sort of clairvoyant. I assure you that is not the case. It is pure coincidence.

So now the question becomes
1) Will the CT get these batteries?
2) Do we want to maintain the advertised ranges with a small batteries (less kWhs), or do we want to maintain the battery size but increase the effective range?

For question 2...I would opt for the greater range; and I will continue to opt for range until I can get a truck with a 1500 mile range...or until charging is as quick and as convenient (readily available) as stopping for gas.
 

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I have a Honda EU3000i (max continuous output of 2800 watts) generator that has a twist lock 120 volt 30 amp outlet. I already have a LS-30 twist lock to TT-30 amp adapter I use with my camper. While not feasible to load this genset into my Model Y, it seems to be perfect for the bed of a Cybertruck. My calculations of 2800 watts at 125 volts yields 22.4 amps of charging power. Not great, but it might help get me out of the Black Rock Desert of Nevada and 123 miles to the Reno Supercharger (or an RV park in Fernley or Pyramid Lake with 30 or 50 amp outlets-no Superchargers there)
 
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My goal is an array of solar panels and a small battery bank to smooth out the charge feed/provide ground.

I have a trip idea I'd like to do to Tuktoyaktuk that will almost necessitate off-grid charging like this.
 

 
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