This slide that highlights past and anticipated future battery energy density gains has been a cornerstone of Tesla (NASDAQ:TSLA ) CTO J.B. Straubel’s presentations for over a decade.

Last fall Mr. Straubel was quoted by InsideEVs saying:

“These batteries are steadily improving every single year – maybe around 5% improvement in their energy density their ability to store energy in a given amount of mass. That’s probably one of the key metrics we worry about. And when we went from the Roadster to the Model S, they have improved by about 40% and when we were designing the Model 3, they were about another 30% better. That improvement just continues on every single year in the background.”

It’s enough to make me want to hum God Bless America. Unfortunately, it’s battery BS because the pack level performance gains have been mouse nuts. It’s just one more real world example of Thomas Edison’s great truth, “Just as soon as a man gets working on the secondary battery it brings out his latent capacity for lying."

Discussions of cell level energy density, measured in watt-hours per liter, and cell level specific energy, measured in watt-hours per kilogram, are interesting to battery geeks but meaningless in the real world because a lithium-ion cell can’t do any useful work until it’s built into a complete battery pack that can power a vehicle or store electricity from a solar panel. In the final analysis, pack level specific energy is the only metric that matters.

It’s hard to find reliable data on pack level specific energy but The X-Files taught us “the truth is out there” if we’re willing to ask the right questions and do some careful research. In my view the following documented pack level specific energy data points are almost unassailable.

When I plug these authoritative values into a graph of Tesla’s 10-year pack level specific energy history, the result bears no resemblance to Mr. Straubel’s graph or his statements that energy densities are increasing at sustained rates. Those things may be true at the cell level, but not at the pack level.

The original Model S battery pack offered a 25.8% improvement over the Roadster. Likewise. The 2017 Model S battery pack offered an 8.9% improvement over the original. The Model X and Model 3 battery packs, however, are both steps backward with lower specific energy than the original Model S battery pack.

The bottom line is that lithium-ion battery technology advances at a glacially slow pace. While this graph is very old, it highlights the shocking difference between technological progress in the electronics industry and technological progress in the battery industry. Between 1990 and 2003, wireless transfer speeds increased by 30x while disk capacity increased by 3,000x. During the same period, the energy density of batteries had a 4x bump with the introduction of lithium-ion in the mid-90s and basically flat-lined for the next decade.

If you updated the graph to include technological advances since 2003, the performance gains for electronics would be several additional orders of magnitude while the energy density gains for batteries would still be within the red oval.

This article focuses on one reason why I think Tesla’s business model is fatally flawed and its inherent investment value is zero. I will discuss others in weeks and months to come. While I can’t encourage anyone to short Tesla’s stock, I believe un-hedged long positions are the epitome of foolishness.

Benjamin Graham, the father of value investing, once explained that in the short run, the market acts like a voting machine – tallying up which firms are popular and unpopular. But in the long run, the market acts like a weighing machine – assessing the substance of a company.

Tesla is clearly a voting machine stock that will maintain an irrational value until the market starts to act like a weighing machine. Since I expected Tesla’s stock to crumble when it was trading in the $30s, I haven't a clue when that will happen. When the music stops, however, it will get very ugly very quickly.

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Disclosure: I/we have no positions in any stocks mentioned, and no plans to initiate any positions within the next 72 hours. I wrote this article myself, and it expresses my own opinions. I am not receiving compensation for it (other than from Seeking Alpha). I have no business relationship with any company whose stock is mentioned in this article.