@shadowjk:
You are correct. However, seeing as the coulomb counter is always off to some degree, I assumed it's just a guess based on voltage.

That would fix some of the issues (with droop). Unfortunately, it still goes up and down (looking at battery-eye) wit at least temperature and SOME droop.

Judging by the attached thanks I'd say several people understood the geek terms. Looking back, I don't really see big words. Volts, amps and watts (one watt is one volt multiplied by 1 ampere for DC (W = V x A) I see interpolation. This is as simple as I can put it, it is a technique by which samples that are unknown are guessed. And it is not a geek word. "Curve fitting by regression analysis" is.

Ooooh, you mean like this:

I get 96% full charge, and live out 24 hours normal usage. That's 96/24 = 4. That's 4% an hour. Ten hour trip, 40%. Stop there or it dies out. I do this manually, by brain, because an app can't know I still have a few calls to make.

Finally, I noticed you dismiss people helping you as geeks. I will not comment on the intention, but on behalf of all the geeks here, I'd like to say thank you.

Nothing crowns 25+ years in schools and universities, all the effort, all the frustration, time spent in hospitals due to high stress, like being spotted half way across the globe, through a forum, by a person who thinks your best whack at simplicity is a geek attack.

You, sir, have made my day.