Huh? If it can be used while it is charging - which is all laptops since forever - then it will run off the adapter while plugged in. Regardless of the battery state. You cannot charge a battery and discharge it at the same time - if it is charging then power must be coming from anything other then the battery. Epically with LiPo batteries which you cannot continue charging after they are full - doing so will cause them to burst into flames. So all LiPo charging circuits will cut off power to the cells once they reach a desired voltage - weather that is considered 100% (aka once it reaches 4.2V) or at a configurable lower amount.
That depends on the age and quality of the laptop. It’s been a while since some started directly running off the cable when the battery is full.
Huh? If it can be used while it is charging - which is all laptops since forever - then it will run off the adapter while plugged in. Regardless of the battery state. You cannot charge a battery and discharge it at the same time - if it is charging then power must be coming from anything other then the battery. Epically with LiPo batteries which you cannot continue charging after they are full - doing so will cause them to burst into flames. So all LiPo charging circuits will cut off power to the cells once they reach a desired voltage - weather that is considered 100% (aka once it reaches 4.2V) or at a configurable lower amount.