That is a an interesting scenario and something similar to one I adopted on my Dell. Charge points for me can be set in BIOS and I had full charge points of 85% and not to charge until it was at 60% or below in the belief that was better for the battery. Lithium cells actually do not like to sit at full charge as that is when most chemical degradation occurs, however......
What I found was the battery suffered. As it discharged in normal use the percentage and time remaining was as expected until perhaps 45% and then it fell rapidly, as much as 5 % in two or three minutes and very quickly reached critical levels. Nothing I tried recovered that situation and I ended up getting a new genuine battery.
I now have the charge point set to 100% but having reached full charge I then deliberately run a while on battery to bring it back down to say 80% and then resume my normal mains usage.
I suspect that what happens is that the cells making up the pack fail to 'balance' unless they fully charge every now and then and this leads to the problem. Cell balancing is nothing new but I hadn't quite appreciated how it occurs only in the last few percentage points of charging. It is managed by the inbuilt circuitry in the battery pack. If you don't fully charge then the cells fail to balance and eventually drift with one or more appearing to accept less charge than the others and that for one thing then sets the overall charge capacity of the pack.
