Trip Energy Usage

Txxthie said:

Is there any data on the internal resistance of the ER and SR packs?

The $20k difference in price was a dead stop for me to option ER. The SR is more than adequate for my needs.

The charging network is the biggest problem right now. If Tesla opened up their network, the SR model would be the #1 seller.

ABRP (A Better Route Planner) shows reference consumption of each vehicle.
ER 447 Wh/mi (2.23 mi per kWh)
SR 537 Wh/mi (1.86 mi per kWh)
This seems quite off as well.

Click to expand...

Tesla's experience would refute that the SR would ever be "the number one seller". Even with their charging networks, their sub 300 mile cars really gave them a black eye. I regularly make trips where my current model Y, rated at 320 mi, is just barely enough. My Chevy bolt, with a similar range to the SR was really just a city/local car.

The SR works great for you, and I am glad. But it is an undersized pack, is not going to work well for most people, and will ultimately tarnish the reputation of the vehicle overall.

Data on the effects of internal resistance, and manufacturers efforts to reduce it is abundant. White papers currently number in the thousands, so you could spend weeks if you like delving into them. In a nutshell, a given current drawn from a cell with an internal resistance of x is y. As the draw rate increases, so does the internal resistance. The opposite is also true, so drawing the same current from two cells results in y² - z², with z being how much less resistance it takes to draw half the amperage from the first cell. These factors differ according to chemistry and physical makeup of the cell, but are present in all cells.

Put another way; if a given load depletes a battery pack in 1 hour, the same load with two battery packs will give you more than 2 hours. This is because of the increased efficiency and less loss from internal resistance.

There is a point of diminishing return when increasing cell numbers when compared to weight in a vehicle, or a "sweet spot." Get too far below that sweet spot, and your cell resistance at a given draw hurts the overall performance of the pack.

Tesla found that sweet spot to be right around the 300 mile mark, but that is a very rough approximation of pack size in relation to vehicle Mass and drag. Anecdotal along with rated evidence, some of which you provide above, would suggest that the Ford sweet spot may be quite similar.

I know that there is some angst amongst SR owners who feel that I am disparaging their vehicle. I am not.

I live in Oregon, and I own an electric chainsaw with a 24" bar. I am not a logger, and for what I use this chainsaw for it is everything I need and more. But living in Oregon, all my logger neighbors snicker and laugh because to them, that is not a chainsaw. It is not only that it is electric, but a bar that small wouldn't even begin to work for what they use chainsaws for. None of that means that my chainsaw is not perfect for me. What it does mean, is that I would seem foolish spending much time trying to convince them that my chainsaw would work for most loggers. Foolish, and in the end it would damage my credibility.

Consider this when evangelizing too hard that the SR truck would ever have a wide appeal to the larger truck audience. That may be a tough sell for even the ER. The numbers presented above from both ABRP and inside EVs (two very solid sources) is really solid evidence that the SR pack is poorly matched to the truck's mass, range aside.

Just as my "perfect for me" chainsaw really should not be evangelized to the larger chainsaw audience as being the best chainsaw for the masses, the same is true with the SR version of this truck. I would highly encourage anybody that can use this version to go buy one, but discourage anybody from ordering it at this point; you can get them cheaper on the open market already.

I would also encourage people to stop saying things like "it will be the perfect vehicle" once the infrastructure improves. It still won't. You can argue with me, and if you like you can write strongly worded letters to ABRP and Inside EVs, but physics is physics.