According to information from Roskachchestvo, you should not charge smartphones to 100%

Sergey Kuzmenko, head of information security at Roskachevo's Center for Digital Expertise, has given advice on charging smartphones, suggesting avoiding fully charging the device to 100%. He recommends keeping the charge between 20 and 80%, calling it a kind of "golden rule". Kuzmenko advises to start charging when the charge level drops below 50% and to turn off the device before reaching full charge.

The expert also expressed the opinion that leaving devices on charge all night is not recommended. He emphasized that the device needs to be allowed to cool down, so it should not be covered, including a pillow.

Kuzmenko also emphasized the importance of using original chargers, claiming that more than 70% of iPhone fires are related to the use of non-original chargers.