My 6s Plus is the same - about 8hrs max. I've never been able to get the battery life others report, and that's with all background/push services off and screen brightness turned down very low. I do have a Samsung A9 chip. However, I purchased a few 6s Plus's, including TSMC ones, and all got about the same 8hrs of battery life - non of them ever got 11-14hrs. In fact, in my non-scientific testing - this particular Samsung lasted the longest of them all while in-use (TSMC may have beat it slightly in standby). I feel the whole TSMC vs Samsung thing is completely overblown, and in reality, it all comes down to getting a "good" chip from the batch - whether it's Samsung or TSCM. There are some Samsung chips that outperform some TSCM chips - it's just that perhaps TSCM had higher yield rates than Samsung, so there were more "good" TSCM chips.