Do you know if it is true that a battery reporting 100% is really only 80% and 0% is really about 20%? I heard that somewhere, but have had trouble confirming it. At least for something like a common smartphone.
It depends on the BMS. Some have big buffers, some don’t. One simple clue is how fast it charges relative to the state of charge. If the battery takes a while to go from 95 to 100%, it more likely goes to a full state of charge. If the battery charges very fast to 100%, it probably has some buffer.
In my experience, vacuum cleaners and smartphones are designed to destroy the battery as fast as possible, while most car manufacturers will have a big buffer and lie about the true 100%. With some notable exceptions though, like Tesla that allows to charge to 100% with some scary warnings or Nissan that designed some early Leafs battery pack without longevity in mind.
Probably depends on the device,but I bet that marketing incentives suggest most won't. I mean do you buy the device that says10 hours battery live or 8 hours battery life?
