# Leaving a cell phone on the charger bad for battery? **URL:** \ **Category:** Factual Questions\ **Created:** [April 9, 2008, 1:59am UTC](https://boards.straightdope.com/t/leaving-a-cell-phone-on-the-charger-bad-for-battery/444551 "2008-04-09T01:59:05Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [April 9, 2008, 1:59am UTC](https://boards.straightdope.com/t/leaving-a-cell-phone-on-the-charger-bad-for-battery/444551/1 "2008-04-09T01:59:05Z")
I have a Motorola KRAZR which I bought in August. Lately I’d noticed that the battery level started to blink soon after making a Bluetooth call for 30-45 minutes. So I took it to the Verizon store and said I wanted to buy a replacement battery. They were nicer than expected and just gave me a new battery since the phone was only a few months old. But the tech looked at the battery and asked if I kept in on the charger overnight. Yes, I plug it in when I go to bed. He said the battery was “swollen” and leaving the phone on the charger when fully charged was bad for it. Does this really make sense? I thought modern phone circuitry regulated the current from the charger to prevent overcharging. Is there really such thing as a swollen battery? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [April 9, 2008, 2:13am UTC](https://boards.straightdope.com/t/leaving-a-cell-phone-on-the-charger-bad-for-battery/444551/2 "2008-04-09T02:13:35Z")
AFAIK, all modern cell phones use LiIon or Lithium polymer batteries, which require a smart charger. Therefore, leaving a phone on the charger when not in use shouldn’t harm it, and is what I do with my phone and computer.