I have the big anker aftermarket battery that comes with its own case. It has to, the battery is triple sized and powered. Its been flawless for 2 years now. I can stream all day, do calls, browse at lunch, look up products. Then at home still stream in the background, and browse the web while watching tv atnight. and still have 20% left.
Its heavier but only really too heavy in a shirt breast pocket. Fine in a pants pocket, jacket or the hand.
It charges and discharges predictably and the battery chip can always give the correct status.