Like any other laptop out there, Dell laptops also possess a finite charge cycle. A charge cycle refers to a complete charging-discharging cycle of a laptop. This number is rather finite and with increasing usage, the power holding capacity of power bank also deteriorates. As for Dell, there are 400 charge-discharge cycle. Therefore, you can charge your Dell Laptop about 400 times. While there is a way to bypass this limitation, but that requires a lot more time and effort. In order to circumvent this limitation, you need to recondition the power bank via the method of deliberate charge and discharge. To explain the procedure in a more directly:
This process would take days to complete, but one it is finished, your laptop would be reconditioned to manage a lot more power than before.