# Why won't my laptop battery last anymore? **URL:** \ **Category:** Factual Questions\ **Created:** [August 28, 2003, 5:17pm UTC](https://boards.straightdope.com/t/why-wont-my-laptop-battery-last-anymore/198236 "2003-08-28T17:17:48Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Opus1](https://avatars.discourse-cdn.com/v4/letter/o/858c86/32.png) [@Opus1](https://boards.straightdope.com/u/Opus1)\ **Post date:** [August 28, 2003, 5:17pm UTC](https://boards.straightdope.com/t/why-wont-my-laptop-battery-last-anymore/198236/1 "2003-08-28T17:17:48Z")
In the last few months, my laptop seems to be getting absolutely atrocious–and in some cases, impossible–battery time. It used to last 1.5-3 hours on battery depending upon what I was doing, and charged at a rate of about 1%/minute. Now I’m lucky if I can ever go half an hour on battery. And charging is much slower too. Just today, it went from 86% charged to 4% charged in 6 minutes! That’s obviously impossible, so there might be some sort of error in reporting the battery level. Can someone give me some ideas why I’m getting such crappy battery times, and what I can do to fix it? It’s a Dell Inspiron 4100. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [August 28, 2003, 5:29pm UTC](https://boards.straightdope.com/t/why-wont-my-laptop-battery-last-anymore/198236/2 "2003-08-28T17:29:26Z")
Heat, whether ambient or caused by rapid charging, is the enemy of most rechargeable battery types, including NiCd, NiMH and to a lesser extent, Li-ion. Heating of the electrolyte leads to a chemical breakdown of its constituents resulting in a progrressively lower capacity over time. Overcharging can also cause a capacity loss, since once the battery is fully charged, the charging current begins working to electrolyze the water in the electrolyte. The only real fix is a new battery, I’m afraid. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [August 29, 2003, 1:27am UTC](https://boards.straightdope.com/t/why-wont-my-laptop-battery-last-anymore/198236/3 "2003-08-29T01:27:23Z")
It really depends on the battery type. I have rescued some NiMHs by going thru a deep discharge cycle a couple times: Turn off all power savings and let it run for a while. Some makers supply a battery learning program that does something like this. LiOns, those just plain go bad with not much help in fixing them. ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [August 29, 2003, 4:02am UTC](https://boards.straightdope.com/t/why-wont-my-laptop-battery-last-anymore/198236/4 "2003-08-29T04:02:49Z")
How long have you been using this battery. Most notebook batteries regardless of formulation give about a year to two years at most before they turn to crap. ---
**Author:** ![handy](https://avatars.discourse-cdn.com/v4/letter/h/b5a626/32.png) [@handy](https://boards.straightdope.com/u/handy)\ **Post date:** [August 29, 2003, 2:16pm UTC](https://boards.straightdope.com/t/why-wont-my-laptop-battery-last-anymore/198236/5 "2003-08-29T14:16:08Z")
I rescued some by just cleaning the contacts. ---
**Author:** ![Will\_Repair](https://avatars.discourse-cdn.com/v4/letter/w/a698b9/32.png) [@Will\_Repair](https://boards.straightdope.com/u/Will_Repair)\ **Post date:** [August 29, 2003, 3:28pm UTC](https://boards.straightdope.com/t/why-wont-my-laptop-battery-last-anymore/198236/6 "2003-08-29T15:28:35Z")
Second **ftg** ’s advice. Any decent battery charger should have a discharge cycle before charging. Some call it “memory.” It is a knee in the curve of available voltage and current. Routinely discharging a battery fully before charging it will flatten the knee in that curve. ---
**Author:** ![Lsura](https://avatars.discourse-cdn.com/v4/letter/l/7993a0/32.png) [@Lsura](https://boards.straightdope.com/u/Lsura)\ **Post date:** [August 29, 2003, 3:44pm UTC](https://boards.straightdope.com/t/why-wont-my-laptop-battery-last-anymore/198236/7 "2003-08-29T15:44:21Z")
> [@](#): > > \*Originally posted by AcidKid \* > \*\*Some call it “memory.” It is a knee in the curve of available voltage and current. Routinely discharging a battery fully before charging it will flatten the knee in that curve. \*\* So, I should occasionally completely discharge my laptop battery to help it last longer? I was told this, and I do this occasionally, but would I be better off doing it on a regular basis (every other month or so)? ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [August 29, 2003, 9:34pm UTC](https://boards.straightdope.com/t/why-wont-my-laptop-battery-last-anymore/198236/8 "2003-08-29T21:34:52Z")
“Completely discharging” batteries of any type is never a good idea. The kind of discharge cycling I talk about is to get to the point where the device won’t start up anymore. There’s still quite a few volts left. E.g., a 1.2V cell might be drained down to .8V. Multiply by the number of cells in the battery to see that “completely” doesn’t apply.