- cross-posted to:
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- cross-posted to:
- [email protected]
Not the Cybertruck story, but perhaps more important.
The Justice Department has been probing Tesla for their exaggerated range claims, and suddenly Tesla has decided to reduce their estimates on these already-released cars.
Erm, that’s not the issue. Gasoline cars have gasoline in the tank, meaning its very easy to estimate how much fuel you have left. In fact its not an estimate at all, its a direct measurement of gasoline in the tank.
The charged electrons inside a Li-ion battery? No good estimate methodology. I’m serious. You can’t measure with a dipstick, there’s no float-bob, you can’t weigh, you can’t do jack diddly shit with Li-ion batteries from any physical perspective.
What Li-ion estimations are is something called “coulomb counting”. You count the electrons in, and count the electrons out. Guess what? It gets inaccurate when things like internal-leakage changes based off of the temperature changes over the past week and a half of charging. This is why phone Li-ion batteries can shutoff at “10%”, because those electrons leaked out in a way that the colomb-counting sensor was unable to detect. (Many, many different sources of leakages).
Its like trying to measure the amount of gasoline in your tank by simply measuring the gasoline in and out of a gas-tank. But what about evaporation? What about a whole slew of other issues? You just can’t plug all leaks in gasoline tanks or Li-ion. But you can just weigh the gas-tank to figure out how much gasoline is there, or you can have a float-bob that tells you how far the gasoline is from the bottom of the tank directly. But literally no such technology exists (or ever existed) for Li-ion.
Maybe in the future this could be invented. But this “last bit of charge phantomly disappeared” is almost innate to battery-tech, at least with today’s level of technology.
In fact, measuring the “zero point” of any battery is famously one of the most difficult problems in battery tech. The only way that seems to reliably work is by discharging the battery all the way to 0% so you know for sure where it is. But otherwise? Good luck finding it (and you shouldn’t discharge to 0% because it damages the battery anyway). So the columb-counting methodology gets less-and-less accurate over time as all of these leakages or other problems add up… and since the 0% point is rarely reached, there’s almost no way to calibrate in practice.
So … blame the consumer for their ignorance? Require a class before they can buy an electric car?
Errrmmm I don’t know what your point is
I’m saying that this problem is innate to any and all electric vehicles with today’s level of technology. And Elon Musk is a fucking liar for trying to suggest that “battery fuel gauges” can reliably determine the “last ounce” of charge.
The honest thing to do for EV proponents is to make sure people know the tradeoffs, so that no one tries to go down to 0% charge unless they absolutely have to. Or maybe for us all to encourage battery-chargers for cars to discharge the battery fully on some occasions (to reliably figure out the zero-point calibration). I dunno what the best solution is, but liars spreading lies about how EVs work is bad for everyone.
The consumer is obviously being misled by Tesla (and Elon Musk) on this matter. And that’s before the shitty range-estimates come into play (literally a conspiracy where Tesla employees have documents that prove that they know about how bad some of these range estimates are, but are working to prevent the public from knowing about it). Some of it is understandable given the difficulty of the problem of battery-estimation. But its always wrong for the company to take an official stance to lie to their customers.
Tesla has temperature sensors. They could give estimated range at the start of a charge based on current conditions. It was only a few hours between supercharging stations. The temperature didn’t change dramatically between 11pm and 2 am.
But they don’t do that for marketing. People would be returning their new Tesla’s bought in the winter when they started it for the first time and it said 150 mile range instead of 250.