I often leave the charger of my cellphone on for much longer than I need to charge, as I am usually not around when it gives the charged battery signal. I was told this is dangerous because it could cause the battery to explode or have its life reduced. It is true?
Many old chargers were not "smart", that is, they did not have the resources to know when the battery was charged, continuing to send current even after full charge. This could cause the battery to suffer some type of overload or damage. In modern chargers, there are features that interrupt the charge current when the battery is fully charged, thus avoiding overcharging problems. For these chargers, it is okay to keep the device connected to the charger and to the mains even after charging is complete.
