Why is my phone charging so slow? Also why does it decrease sometimes?

[CRob2]

My phone usually charges fast. This is my second replacement phone...and this morning it said 30% when it was on the charger for the whole night. So when I went to school I plugged it into my laptop and it decreased after a while when I tried it again, it started charging. Had this problem before but now its taking hours to get up to 50%. Sorry for the long post.

 

[B. Diddy]

Welcome to Android Central! Overnight, I assume you were charging while plugged into a wall outlet, right? Remember that USB charging is significantly slower than AC charging.

Sometimes, either the cable or the wall plug can become faulty, so that the device will think it's charging via USB, rather than AC. Plug your phone into the wall outlet, go to Settings>Battery, and see if it says "Charging (AC)" or "Charging (USB)." If it says the latter, try a different cable and/or plug.