I would like to set charge cutoff point. Battery lifetime is dramatically longer if the maximum charge is limited to under 90% or so. This reduces run time, but greatly extends the number of charge / discharge cycles.
I agree that it's a good idea, but unfortunately, the battery charge/discharge logic is all handled by the system BIOS. There's no standard API to configure how a battery charges or discharges.
The best that I can do is display a popup box at a certain percentage to remind you to disconnect the power cord.