Colorado Teardrops Boulder EV camping trailer with 75kW battery pack

[SpaceDoc]

For those folks saying you can’t take your CT to the backcountry due to range issues, here’s one solution…

https://www.greencarreports.com/new...st-charges-evs-with-75-kwh-of-extra-batteries

Also here…

https://www.greencarreports.com/news/1133124_towing-with-an-ev-are-electric-trailers-the-future

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[Ogre]

This is one of the ways Tesla could lead the way here, if they added some communications with the trailer, it could go a long ways here. Currently the only way is slaving the trailer to the brake lights and having some kind of accelerometer on the trailer. Tesla could build a full interface where the truck could communicate with the trailer, telling it when to accelerate, when to brake, and when to just roll. The truck could even display trailer charge state on the truck's console.

I don't think it makes a ton of sense to have a trailer along that is just an extra set of batteries, that means on the return trip, it's just dead weight. A trailer with a modest 20kWh battery and a generator that intelligently applied power on climbs and regenerated power on descents, now that would be much more interesting. Particularly if it cooperated with the truck.

 

[Crissa]

Well, the travel trailer is dead weight on the way home, batteries or no.

-Crissa

 

[Kevinb2]

Extremely high price. I would rather just save up for the tri motor option and have all the extra 20k-30k cash for supercharging near the point of off-roading. I sure wouldn't want to be hauling a trailer that would be jumping up and down, getting bogged in mud, and being more of a worry than help. If I do need more range, a propane generator/tank will be far cheaper, weigh less, and is much smaller; able to be secured inside of the vault.

Edit: see to the Cybertruck Truck Guy's video of his thoughts:

 

[ajdelange]

Uh oh! My sister had (note use of past tense) a friend who went to get a refill for his barbecue propane tank and threw the new one into the cab of his truck. Have you ever noticed that the propane tanks on travel trailers are mounted outside? Have you ever noticed the signs that prohibit taking them through tunnels? Unless the bed of the CT can be totally isolated from the cab I would not advocate carrying propane bottles in the bed. I'll note that I did have a gas bottle in the bed of my SR5 which sprung a major leak within a few hundred feet of the store. Had it been inside the truck (not that it would have fit - 100# CO2 siphon).

Now onto range off road. I got focused on this when someone asked about taking his R1T (180 kW battery) from Assateague to Chincoteage on the beach. It's only 27 miles but a little checking revealed that rolling resistance coefficient for car tires on sand is 0.2 - 0.4 which is 20 - 40 times that for cement. Assuming the CT to weigh 2500 kg and using 0.3 for the coefficient the rolling resistance will consume 2500*9.8*0.3*1609/3600 = 3285 Wh/mi. If the drive train has to deliver 3285 wH/mi and it's efficiency is 90% then that means another 328 Wh/mi is lost to heat making the total load 3613 Wh/mi plus drag load which, as you won't be driving at freeway speed on the beach, I think we can neglect. The 27 mile drive would use 97.6 kWh. Assuming the TriMotor to have a 200 kWh battery that's 49% of it equivalent to 244 highway miles. And it is 98% of a 100 kWh battery (about what we expect for AWD CT). Thus you can't do this little junket in the AWD (any more than you can do it in the "large" R1T) but you can do it in the TriMotor (and the "max" R1T).

The "solution" proposed in the video, is to add 345 pounds of generator and propane tank to the truck load. The rolling resistance formula shows the cost of doing that to be 1.1*(345/2.2)*9.8*.3*1600/3600 = 255.4 Wh/mi so that for the 27 mile run additional consumption would be 27*(345/2.2)*9.8*.3*1600/3600 = 6085 Wh - another 3% of the battery. Total consumption with this load would be 1.1*(2500 + 345/2.2)*9.8*.3*1600/3600 = 3818.73 Wh/mi so that a 7.5 kW generator at 90% charging efficiency would yield 0.9*7500/3818.7 = 1.78 miles for each hour of charging.

All this sounds very scary, of course, and it is meant to scare you into paying close attention to consumption when setting out on an off road adventure or, indeed, when doing a trip on the freeways. The truck will come with excellent tools which let you do this.

Not all off road substrates will exhibit rolling resistance coefficients as high as 0.3. FWIW I do a lot of driving on dirt roads during the summer and I don't see much difference in consumption between using them and paved roads the rest of the year. But I do not use them when they are a gooey muddy mess in the spring. The coefficient would definitely be higher then.

It is also a very compelling argument for the TriMotor configuration. I used to say that the three motors and big battery were in the TM for the towing. It is now clear that they are also there for driving on lousy surfaces.

 

[Crissa]

Tunnels do not ban small amounts of materials stored as part of groceries or as fuel tanks on vehicles.

-Crissa

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