I am having the same problem. Mid 2009 Macbook Pro, running OSX 10.11.6, obsolete, no longer Apple supported. My original battery lasted 10 years, needed it replaced. I followed all the instructions as to calibrating the battery and resetting SMC and PRAM. It now sleeps at 80% of charge. Sometimes a key stroke will wake it, sometimes not. It always wakes after closing the lid and waiting a good 30 seconds for whatever unfinished sleep process to complete. If I continue to wake it in this manner, eventually the charge will fall below a certain percentage and it will run until the battery depletes itself. That charge level is somewhere around 77-78%.
I have not tried the above option yet. The logs clearly shows that the power management system knows that the battery has 80% of charge remaining. So the issue is originating somewhere else. I have performed multiple SMC resets, both by a.) removing the power source and the battery connection and, b.) through the shift-control-option-power key combination while off. Setting hibernatemode to 25 might be a quick fix, but it doesn’t resolve the issue. There is a setting somewhere else that is telling the computer to sleep at 80%.