Iphone 5 not charging

My husbands iphone 5 is not charging. There's nothing wrong with the charger because ive tried my ipad and my iphone and its working fine. Its updated. Ive tried cleaning it and power restart still doesnt work. But when i turn it off and plug it in the phone turns on but still not charging. Its already down to 3%! Wish someone can help me with this. Thank you!