from the MacBook user guide:
To calibrate your battery:
- Plug in the power adapter and fully charge your MacBook battery until the light on the
power adapter plug changes to green and the Battery icon in the menu bar indicates
that the battery is fully charged. - Allow the battery to rest in the fully charged state for two hours or longer. You may use
your computer during this time as long as the adapter is plugged in. - Disconnect the power adapter with the MacBook on and start running it from the
battery. You may use your computer during this time. - Continue to keep your computer turned on until it goes to sleep. Save your work and
close all applications when the battery gets low and before the system goes to sleep. - Turn off the computer or allow it to sleep for five hours or longer.
- Connect the power adapter and leave it connected until the battery is fully charged
again.
When your battery gets low, you’ll see the low battery warning dialog on the screen.
Important: Repeat the calibration process every two months or so to keep your battery
fully functioning. If you use your MacBook infrequently, it’s best to recalibrate the
battery at least once a month.
[...] Mi stavo chiedendo se ci sono comportamenti particolari da tenere per allungare la vita delle batterie dei laptop. Il D620 è molto simile ai nuovi MacBook, forse questo è un link utile da provare, intanto testo questa utility di calibrazione [...]