I had %1 of charge before going to sleep last night. My phone was turned off and not charging all night (~10 hours). I woke up and I turned on my phone as usual.
And I have %19 of charge. How is this possible? Does anyone have an explanation?

(This is probably my second time facing this.)
(P.S: Nights are cold here)

I wanted to say because of heat, but lipo batteries regain some charge if they have more cells, because they balance each other out.

Also the percentage on your phone is a big fat lie to make it feel like the battery saver mode actually does something

@yellow-dog Now that makes sense, thank you.

Yeah, "power saving" mode. Right...

Battery voltage is also affected by load: the more current you're drawing from it, the lower the voltage you read at the battery's terminals.
Add to that the non-linear charge curve (it takes a steep dive towards the 3V end), and you get some really unintuitive behaviour, especially if you're calculating your charge % linearly.

Most devices calculate the charge as "how long will the battery last at current usage level"/"how long a full battery will last at average power use".
makes for a weird "windows copy" like estimates.

I've tried the same thing with my phone turned on all night. It doesn't "charge" itself. On the contrary, my battery percentage dropped from 75 to 68. (I don't know if it's about being lower than %10 or something. I'll try that soon.)

And I really started to think different about my phone battery thanks to you guys.