What happens if a person leaves a mobile or laptop charger plugged in all the time?

Leaving chargers plugged in does not usually overcharge phones or laptops because modern devices have built-in systems that automatically stop charging once the battery is full, reported News18. However, leaving a charger plugged in constantly can slowly waste electricity through "vampire power", increase power bills and shorten charger life. Faulty chargers left plugged in could be a fire hazard.