Why is my battery getting hot while charging?

[banashree das]

windows battery

Why my Nokia Lumia 730 charger is getting hot while charging?

 

[xandros9]

You're asking two different things.

The charger itself, the wall plug gets hot/warm when charging. That's normal operation for most any charger, whether a laptop power supply/brick or the USB wall plug of a phone. (However, catching fire, is not normal operation)

If you phone is getting warm while charging and stuff, that's just the byproduct (same with the charger) of a less than 100% efficient power transfer. As long as neither is getting too hot to touch, I think you're still in the realm of safety.

Why? Moving electrons produces heat and whatnot, in a nutshell. I'm not an electrician though, so I could be somewhat wrong.