# Should phones be charged before the battery is empty? **URL:** \ **Category:** Factual Questions\ **Created:** [May 17, 2016, 3:30pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003 "2016-05-17T15:30:54Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [May 17, 2016, 3:30pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/1 "2016-05-17T15:30:54Z")
They used to warn against recharging batteries before they were mostly discharged. They build a memory or something. What’s the rule on phones? Wait or is it OK to charge early? Like 75% for example? ---
**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:** [May 17, 2016, 3:39pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/2 "2016-05-17T15:39:10Z")
We’ve only had a million threads on this topic. Just charge it whenever you want to. The integrated charge controller handles all the details. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [May 17, 2016, 3:42pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/3 "2016-05-17T15:42:12Z")
> **[Memory: Myth or Fact?](https://batteryuniversity.com/article/memory-myth-or-fact)** > > BU meta description needed... This article talks about modern batteries and exercising them. Doesn’t say much about when to recharge them and waiting till empty. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [May 17, 2016, 3:56pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/4 "2016-05-17T15:56:01Z")
> [@aceplace57](#): > > [Memory: Myth or Fact? - Battery University](http://batteryuniversity.com/learn/article/memory_myth_or_fact) > > This article talks about modern batteries and exercising them. Doesn’t say much about when to recharge them and waiting till empty. That article talks about Nickle-Cadmium batteries, and to some degree, NiMH. Modern cell phone batteries on Li-Ion, and don’t have the memory problem. That article is not relevant to current cell phones. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [May 17, 2016, 4:00pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/5 "2016-05-17T16:00:38Z")
> [@aceplace57](#): > > [Memory: Myth or Fact? - Battery University](http://batteryuniversity.com/learn/article/memory_myth_or_fact) > > This article talks about modern batteries and exercising them. Doesn’t say much about when to recharge them and waiting till empty. No, the article talks about old battery technologies (NiCd and Ni-MH). Modern phones have lithium ion batteries, and sophisticated battery management circuits that won’t let you over-charge or over-discharge the battery even if you try. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [May 17, 2016, 4:02pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/6 "2016-05-17T16:02:44Z")
Modern phones use lithium ion batteries which don’t have the memory problem (that was mostly old Nickel-Cadmium batteries). Lithium ion batteries are lightweight and have a high energy density for their size, which makes them great for laptops and cell phones. Unfortunately, the longevity of lithium ion batteries sucks. They start dying from the moment they are made, and there’s not much that you can do about it. The big killer of lithium ion batteries is heat. This is more of an issue for laptops than cell phones, but it is much better to keep the phone on your desk than it is to keep it in your pocket. As for charging, lithium ion batteries tend to last slightly longer if you don’t keep them fully charged. Mostly though, it doesn’t matter much how you treat them. They are going to die young no matter what you do. In a laptop you’ll often get about 3 years out of them due to the heat inside a typical laptop. In phones they tend to last a bit longer, but don’t expect to get more than about 5 years out of them. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [May 17, 2016, 4:27pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/7 "2016-05-17T16:27:23Z")
Just wanted to double check. These smart phones go down so quick after watching a few YouTube vids or web surfing. I’ll start charging it more frequently instead of waiting till it’s nearly dead ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [May 17, 2016, 4:39pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/8 "2016-05-17T16:39:15Z")
I’ve noticed these smart phones get warm. Mine is too big to fit in any pocket. But letting it cool on the desk is a good tip for people that do carry it in a pocket. ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [May 17, 2016, 4:52pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/9 "2016-05-17T16:52:07Z")
> [@beowulff](#): > > The integrated charge controller handles all the details. I recently came across [this fascinating answer from StackExchange](http://electronics.stackexchange.com/questions/230155/why-is-there-so-much-fear-surrounding-lipo-batteries/230164#230164) concerning how critically important these charge controllers are: > [@](#): > > [T]he only reason this now ubiquitous chemistry hasn’t murdered you and/or your family several times over is because these cells aren’t charged unattended. You may not be attending it personally, but every single one of those lithium ion batteries has a significant amount of protection and monitoring circuitry that is permanently integrated into the pack. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 17, 2016, 5:01pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/10 "2016-05-17T17:01:26Z")
> [@engineer\_comp\_geek](#): > > …it is much better to keep the phone on your desk than it is to keep it in your pocket. _Much_ better? :dubious: I mean sure, ~90-ish is warmer than 70, but does keeping a phone in my pocket (instead of my desk) really make a noticeable difference in battery durability? ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [May 17, 2016, 5:32pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/11 "2016-05-17T17:32:09Z")
> [@Machine\_Elf](#): > > _Much_ better? :dubious: I mean sure, ~90-ish is warmer than 70, but does keeping a phone in my pocket (instead of my desk) really make a noticeable difference in battery durability? Probably somewhere around a 10 percent difference in the total lifespan of the battery. ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [May 17, 2016, 7:12pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/12 "2016-05-17T19:12:56Z")
> [@aceplace57](#): > > I’ve noticed these smart phones get warm. Mine is too big to fit in any pocket. But letting it cool on the desk is a good tip for people that do carry it in a pocket. The heat is from the backlight. Turn-off the back light before you put it in your pocket and you should be fine. ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [May 17, 2016, 7:27pm UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/13 "2016-05-17T19:27:28Z")
Sometimes you can have an app running in the background that is using up a lot of system resources, and therefore power. So every so often shut down all the apps on your phone. Also sometimes helpful is shutting off wifi. My last phone used to suck down power when wifi was enabled. But my new phone doesn’t have that problem. ---
**Author:** ![Noel\_Prosequi](https://avatars.discourse-cdn.com/v4/letter/n/b19c9b/32.png) [@Noel\_Prosequi](https://boards.straightdope.com/u/Noel_Prosequi)\ **Post date:** [May 19, 2016, 3:51am UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/14 "2016-05-19T03:51:24Z")
I checked MikeS’s link, and it was indeed fascinating. I gather rapid discharge can create problems not just when the discharge is occurring, but more particularly when the recharge afterwards occurs. Is that the problem with hoverboards and their risk of explosion (prompting the odd celebrity [meltdown](http://www.smh.com.au/lifestyle/celebrity/russell-crowe-slams-virgin-airlines-for-not-allowing-him-to-check-in-combustable-hoverboards-20151229-glwg6v.html))? I imagine that mass-movers like hoverboards are rapid dischargers. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [May 19, 2016, 4:05am UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/15 "2016-05-19T04:05:46Z")
> [@aceplace57](#): > > [Memory: Myth or Fact? - Battery University](http://batteryuniversity.com/learn/article/memory_myth_or_fact) > > This article talks about modern batteries and exercising them. Doesn’t say much about when to recharge them and waiting till empty. That article was updated on 3/10/11. In a field that evolves nearly everyday, it’s not really accurate to say a 5+ year old article is about modern technology. As others mentioned, phones use li-ion batteries now, which your article doesn’t even mention. ---
**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:** [May 19, 2016, 4:29am UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/16 "2016-05-19T04:29:32Z")
> [@Omar\_Little](#): > > The heat is from the backlight. Turn-off the back light before you put it in your pocket and you should be fine. Not really. Most of the heat is from the processor / radio ICs. ---
**Author:** ![Atamasama](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/atamasama/32/12961_2.png) [@Atamasama](https://boards.straightdope.com/u/Atamasama)\ **Post date:** [May 20, 2016, 2:15am UTC](https://boards.straightdope.com/t/should-phones-be-charged-before-the-battery-is-empty/755003/17 "2016-05-20T02:15:59Z")
Don’t drain a modern phone to empty and then leave it uncharged for a long period of time. > A “long period of time” is something like a year though, so you don’t need to be paranoid about it and most people don’t need to concern themselves at all about it. If you’re using a device that can alternately run either off the battery or run off of AC power (like a laptop) then the less you use the battery the longer it will last. > **[How to get the most from Li-Ion batteries](https://www.zdnet.com/article/how-to-get-the-most-from-li-ion-batteries/)** > > Six tips for getting the best possible life out of the Li-Ion batteries inside your smartphone, tablet or notebook. Draining and recharging a battery repeatedly will wear it out. It’s not a matter of frequency but total charge. In other words if you drain a battery halfway before recharging it back to full, then do the same thing again, that’s the same as draining it fully once and fully recharging it.