Read my previous post again
Charge stop threshold : the threshold your battery won't exceed when it's charging.
Charge start threshold : the threshold you have to reach before your battery starts charging again.
So, with a power source connected to you laptop, the battery will stay at 89% for now.
Disconnect the power source, you battery will discharge.
Connect the power source again : if the remaining capacity is higher than 15%, it won't charge; if it's lower than 15% it will charge, up to 95%.
So, if you want your laptop to be "almost charged all the time but not 100%", you should set a start charge threshold higher, like 85% for instance, and a stop charge threshold at 95%. But if you use it almost always connected to a power source, something like 30% / 75% is enough.
I hope that's clearer