My friend says that if you leave regular batteries in something electrical, then use the power cord without?

Question

taking out the batteries, the batteries would charge and possibly explode. I dont believe this, is it possible?

Answer 1

It depends whether its a portable thing that can charge it's self when pluged in like a camera. but most things just bypass the batteries when they are pluged in. any way the baterries would hardly explod more like split or leak.  

Answer 2

it depends on what the unit is. if it is a smoke detector or an alarm radio then they are built in a way that they will use house current first then in case of electric failure they will then use the batteries. -blurey