It would be great if one could configure a hysteresis function for the battery charging subsystem. For example to let the firmware charge the battery to 80% (upper hysteresis threshold), but, after that event, only re-charge it if the capacity drops down below - say - 70% (lower hysteresis threshold).
This should increase the battery live very much for devices connected to a charger for extended periods.
Ideally the upper and lower thresholds would be configurable via the BIOS and the operating system (i.e. e.g. sysfs on Linux).
This is an improvement over the status quo, where one can only specify on upper ‘Battery Charge limit’ in the BIOS. Thus, trickle charges in tiny charge cycles still happen. For example, when you set that limit to 80%, after a small self-discharge amount of - say - 1% - the firmware immediately re-charges again up to 80%. Which is not good for battery life!
This feature is available in other mobile devices. Best example are perhaps Thinkpads where the firmware exposes
Related discussion: Battery Management with min/max limits possible?