How does Battery Life Extender+ work?

Question

laptops

Can you please tell me how the Battery Life Extender+ function works in the laptop manufacturer's software?
They write on the Web that it supposedly extends battery life by limiting its charging to 80-85%. But I read that it is just useful for the battery to make a full charge cycle up to 100%. And I can confirm this with my own experience of using the tablet: every day I leave the tablet for the night and it always charges up to 100%. It's been 5 years (since 2013) and it still holds a charge for at least 6 hours of active use (was 8 hours). Battery data from AIDA64:
Technology: Li-Po
Capacity (Android report): 3448 mAh
Capacity (from database): 3950 mAh
Agree, this is not bad after 5 years of operation. So how does it actually work?

Answer 1

The most stable position of the chemical reaction in Li-Ion batteries is at 2/3 charge (67%, 3.7 V). A high charge level (100%, 4.2 V), as well as a low one (0%, 3.0 V), negatively affects the battery capacity (however, it decreases over time anyway). My Lenovo Yoga 13 has a "life extension" function, charging stops at 66%. Cooler Thinkpads let you manually adjust the stop charge percentage.
It is also worth noting that with the active use of a laptop outside the home, charging by 67% is not very profitable - we lose a third of the charge. That is why your super-duper-tech-plus charges by 85%, and not by 67%.
I dare to note that the tablet battery is very different in the device from the laptop battery. The laptop requires higher voltages for operation, therefore it uses several series-connected battery cells ("cans"), as a result of which the reliability of the battery decreases significantly - it often happens that one of the "cans" is charged too much (more than 4.2 V) or too is strongly discharged (below 3.0 V) (at the same time, the voltage on the battery as a whole does not go beyond the permissible range due to the rest of the cells). As a result, only one can is worn out, and the entire battery dies. Therefore, the tablet can be charged up to 100% and discharged to 0%, and a laptop in this mode of operation can quickly fail (in general, it depends on the battery controller - in my Yoga 13 the battery is fine after 6 years of service,
Questions, comments?