This school of thought believes that no matter who you are, if you miss your night sleep, it will affect your next day at work… Human body refreshes at night to prepare for a full day ahead and so the smartphone battery is entitle to have the same treatment.
When you charge your phone overnight, the cell inside your phone will charge for the two hours or so that it takes to get back to full strength. For the rest of the night, software will stop the charging process once the battery is back to 100%. This prevents damage that could be done to the battery by overcharging. But it doesn't prevent the battery from generating heat.
Putting your battery under your blanket or your pillow while charging at night could be limiting the ability of your battery to charge up to full capacity. For example, if your battery hits a temperature of 104 degrees Fahrenheit for a year, you will only recover 65% of the battery's capacity when you charge to 100%. Even more amazing, if your battery is running at 140 degrees Fahrenheit for just three months, the cell will lose 40% of its capacity.
Look at the data above, and it clearly show that charging your phone overnight kills the battery cell faster, while charging it during the day and keeping it charged between 40% and 80% makes the battery last longer.
Overnight charging kills the battery faster than cancer due to overheating. How often do you charge your phone battery overnight?
Source: Battery University
