I bet that you Fast Charging topic is well known to you. The idea is simple. Modern smartphones has much higher capacity than years ago. For an example, four years old Samsung Galaxy S3 has 2100 mAh battery and the newest Samsung’s flagship model (i.e. Galaxy S7 Edge) has over 71% bigger battery (i.e. 3 600 mAh). Therefore, there is a need to charge faster these large batteries.

A lot of people charge their smartphones during the night next to their beds, so the smartphone has several hours to be charged. However, the power consumption is also higher, because we use our smartphones for Internet browsing, gaming etc. a lot. Very often we need to charge our mobiles during the day. This a reason why we have several fast charging solution available on the market:

However, a lot of people think that this kind of techniques are harmful for batteries.

The newest beta update of Android Marshmallow for Sony Xperia Z2, Z3 and Z3 Compact (i.e. the build number 23.5.A.1.238) introduces new feature called Soft Charging. This will increase the battery lifespan by not letting it to be charged to 100%. This will cause that the battery lifetime will be reduced, but will benefit in the future.

This feature may be very useful, because modern smartphones have non-removable batteries. So if your battery has reduced capacity, then you have to buy new smartphone.

source: http://www.xperiablog.net/2016/06/21/xperia-beta-update-with-soft-charging-feature-now-rolling-23-5-a-1-238/