My understanding is that the battery pack on my 2014 SR (no PT), rated at 11.4kWh, really provides no more than 10kWh real-world. It makes sense: There are four 25Ah cells in parallel, with however many in series, so that means the pack as a whole is rated for 100Ah of capacity. The cell voltage, which is the sum of however many cells it has in series (I want to say 28 but I'm not sure I remember correctly), I do remember as being 103V nominal. When the charger finishes the charge cycle, the cell voltage peaks a bit to 114V, which when multiplied by the 100Ah capacity, gives the 11.4kWh rating. This is the "salesman's number"; it's the highest number you can reasonably claim. But in reality, the battery voltage quickly drops from it's peaked value down to near the nominal value, which it stays near for most of the discharge cycle, drooping a bit more as the battery ends its discharge cycle. So a much more realistic number for the "11.4kWh" battery is 10kWh, which all my reading says is pretty close to the actual value. Zero can't use that number, however, because nobody else rates their battery packs that way -- one guys overstates their numbers, then everybody else has to do it or look like they're underperforming.
The solar panel people have the same problem, but even worse. A solar panel may provide 3.5A into a dead short, and 18V open circuit, so the sales people multiply those two numbers together and call it a "60W" panel. But the reality is it won't provide anywhere near 60W in real life, no matter how bright the sun is, because it can't provide 3.5A and 18V AT THE SAME TIME. In reality, it's more like a 40W panel, 45 at the most. But once the first person did it that way, everybody has to do it that way, or the customers would just buy the "higher-power" panel without digging into the real situation. Specsmanship, pure and simple, but everybody has to play the same game.
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Topic: Can someone check my math? (Read 1695 times)