SEARCH

How-To Geek

Should I Leave My Laptop Plugged In All The Time?

Should you leave your laptop plugged in and charging when you’re not on-the-go? What’s best for the battery? What’s best for your user experience? Read on as we investigate.

Image available as wallpaper-size download here.

Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-drive grouping of Q&A web sites.

The Question

More than one SuperUser reader was curious about the whole matter of laptop batteries and wall current. ClickUpvote inquires:

When your laptop’s battery is 100% charged, should you leave it plugged in so any battery power doesn’t get used, or will that cause overcharging, overheating, etc.? Should the laptop be unplugged when the battery level is 100%?

He echoes a similar question asked by Moayad Mardini:

When I’m at home, is it better to use the laptop plugged into AC power, or with just the battery, for the overall battery life?

So what was the verdict? Should you leave your laptop almost perpetually tethered to the wall or only charge it when the battery charge is running low?

The Answers

The answer to the question isn’t a cut and dry “Yes, leave it tethered” or “No, unplug it”  because of the variety of laptop designs, their battery types, and the integrated charging circuit that recharges the battery. That said, the insights provided by SuperUser contributors cover the most common scenarios laptop owners will come across. Contributor Charles Roper writes:

It won’t make all that much difference. What will shorten battery life is temperature: If it gets hot, it will shorten the battery life. Best thing to do, if you are able, is to remove the battery while you’re at home and keep it somewhere cool.

If it’s a Li-ion battery, then they don’t like to be completely discharged, so make sure you charge them regularly. Wikipedia:

Lithium-ion batteries should not be frequently discharged fully and recharged (“deep-cycled”), but this may be necessary after about every 30th recharge to recalibrate any electronic charge monitor (e.g. a battery meter). This allows the monitoring electronics to more accurately estimate battery charge.[26] This has nothing to do with the memory effect.

More tips can be found here:

What about the “Remove the battery!” camp? It turns out that while removing the battery can be beneficial, the situations in which it is beneficial are fairly limited. Splattne writes:

This page has a good answer: “it depends”


The answer is: YES and NO, it depends on the situation.

Having a battery fully charged and the laptop plugged in is not harmful, because as soon as the charge level reaches 100% the battery stops receiving charging energy and this energy is bypassed directly to the power supply system of the laptop.

However there’s a disadvantage in keeping the battery in its socket when the laptop is plugged in, but only if it’s currently suffering from excessive heating caused by the laptop hardware.

So:

  • In a normal usage, if the laptop doesn’t get to hot (CPU and Hard Disk around 40ºC) the battery should remain in the laptop socket;
  • In an intensive usage which leads to a large amount of heat produced (i.e. Games) the battery should be removed from the socket in order to prevent unwanted heating.

The heat, among the fact that it has 100% of charge, is the great enemy of the lithium battery and not the plug, as many might think so.

The best plan of attack then, is to monitor your hardware to ensure you’re not overheating your battery and be concious of the limitations of the type of battery in your device–for the majority of users, a Lithium-Ion battery.

For more battery saving tips, laptop-oriented and otherwise, make sure to check out some of our feature articles on the subject, including:


Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion threads here and here

Jason Fitzpatrick is warranty-voiding DIYer and all around geek. When he's not documenting mods and hacks he's doing his best to make sure a generation of college students graduate knowing they should put their pants on one leg at a time and go on to greatness, just like Bruce Dickinson. You can follow him on if you'd like.

  • Published 09/25/12

Comments (28)

  1. LadyFitzgerald

    Lenovo recommends on my G570 to set Power Management to maintain the battery at around 50% when running mostly on the power supply to increase battery life. I do that unless I’m going to be on the road, then I reset it to fully charge the battery a day or two before I leave. I set it back to 50% after I get back home.

  2. Kodess

    Always had my laptop charging with battery inside. After 1 year of 6 hour a day use (college), the battery now lasts me 10 minutes if I ever need it.

  3. Lee

    Currently, I have a docking station for my laptop, so when I’m in my dorm the battery is always charging. I never thought about the heat affecting the battery, but it feels like there’s a fan right above the battery, so I think I should be OK (I just put my hand there and it was cool-ish air coming out, not warm). My battery (extended) can last me about 5 hours, and I definitely don’t have the maximum power saver settings set.

  4. clb92

    Does this apply to lithium-polymer batteries too?

  5. samcal

    I leave the batteries installed – but for reasons not discussed. I no longer worry about power outages ‘eating’ my work.

  6. LadyFitzgerald

    @ samcal. That’s one reason I leave my battery installed. It’s one heck of a UPS and has saved my work several times due to power outages.

  7. vladimiro

    When I’m at home, I charge the battery lithium-Ion of my laptop to 50% and remove it. If I need to use the laptop outside, I charge the battery to 100% and I use it. When I come back at home, I charge again to 50% and remove it. This is simple, and my battery is still like when I buy the laptop.
    Really interesting post! Thank you!

  8. bemymonkey

    It all depends on how well the charging circuitry in your laptop works, and how it’s optimized for battery longevity. Lately I’ve got mine set to only charge when the charge level drops below 80%, meaning that in a worst-case scenario, I’m leaving the house with only 80% – a good hour or two less than 100% with the small 6-cell I’m currently using as my beater (read: always-in) battery. This has the advantage of only charging if the battery has actually been used for a total of two hours or so…

    Keeping your battery set to charge when it drops below 95% (as is the default on most laptops and often can’t be changed) causes it to constantly cycle between 9x% and 100% every time you unplug for half an hour… that’ll kill your battery even faster than the heat mentioned above.

  9. Santo

    My 4 months old laptop used to give 4 hours battery backup initially but now it gives 3 hours 45 minutes backup.

    I used to disconnect from power when the charge is full and connect to power only when the charge falls below 10%. Within this 4 months, I had done battery calibration twice.

    So, I feel the life of a Lithium battery in a laptop depends on its circuitry.

  10. r

    I just keep power plugged into my Dell m6700, or e-port all the time
    if I need a new battery I order one.

  11. jeepmanjr

    FWIW, I believe all batteries should be maintained at 100%. That’s what I’ve done with every battery I’ve owned, including those in non-computer applications. It is rare that I ever have to replace a battery. I have a Dell Latitude C640 that I’ve owned since the mid-90′s and have only had to replace the battery once. If it’s not running on DC, it’s plugged in. Works for me! :-)

  12. hfxmike

    Is there any freeware to allow me to set the battery charge level? How are you guys doing it?

  13. Neville

    I read most of these comments about batteries in my lap-top and I think they are very useful. Keep it up

    Neville.

  14. Paul

    I’m with samcal and LadyFitzgerald. Many times having my laptop battery constantly inserted has saved me from unexpected power cuts. I can attest to the effects of heat though. I have a gaming laptop that tends to run hot and, when new, I got four hours plus from the battery. 18 months later and I’m lucky to get 30 seconds; there’s not even enough stored charge to boot with. It’s enough to compensate for brown-outs, which is why I still keep it fitted.

  15. Scott

    I leave my battery in because I never know when I may need to grab my laptop quickly and I don’t want the hassle of replacing my batttery. But my normal usage is leaving it charging all night, because it stays in hibernate in my backpack all day at school. And I use my laptop in second period for 1 hr 45 min daily. I usually use my laptop on battery at home after school until I feel that I need to charge it (so around 10%).

  16. Allen

    I normally keep mine plugged in, but if it is mostly charged, I will just keep it from charging using the dell battery meter. I usually leave the batter in, that way, as mentioned above, I don’t have to be afraid of power outages.

  17. LadyFitzgerald

    @ hfxmike. My Lenovo G570 came with an Energy Management program that allows me to set the charge level at around 50% (it’s actually 46% on my machine). I suspect most laptops will also have something similar. Since the Lenovo will run on AC once the battery has reached 46%, the battery just kinda-sorta sets there unless the power goes out, then it takes over. The mobile home court I live in had some power issues for about a month back that took took a month to diagnose and fix. Having the battery ready to take over when the power went south saved my ample asset several times.

    My battery has a full run time of 4:17 hours. It was a bit higher when I got the Lenovo back in June but after it dropped, it has stayed consistant.

  18. 0xRiddle

    this is a rather unique approach . When at home I turn off my laptop and use the desktop :)

  19. Mark

    an easy way to determine the unknown information is to use Speccy.

  20. SoL

    @ 0xRiddle : Not really, many people connect their mobile computers to dock stations (ex: an E port ) and then connect multi-monitors, keyboards or any other hardware to that. It’s a very practical way to do things actually.

  21. Zakariah

    I heard that if you leave on for too long, it will stop charging. Is that true?

  22. malachipclover

    40C for good life… guess my battery’s not lasting very long. My laptop averages around 70C when idling, and between 80-95C when under load…

  23. Tv recharge

    Thanks to sharing this wonderful blog, I newly purchase a dell company laptop the same question is also arise in my mind. After reading your blog. I find that i leave my laptop plugged in all the time.

  24. recon290

    I don’t leave it plugged in unless I am nearby. If you attend school in the state of Florida then you know it’s the lightning capital of the world. You need to make sure you actually have a surge protector and not a six plug extention cord. Thunderstorm = unplugged.

  25. LadyFitzgerald

    I always unplug mine during a thunder storm and when it’s not in use.

  26. Sam Sticka

    Usually it is not a good idea to continually leave your laptop battery in at 100% and have it plugged in. I’ve done some reading on this and supposedly the new lithium ion batteries don’t have the ‘memory effect’ like older batters – so leaving them plugged in while at 100% shouldn’t effect their lifespan. But from personal experience on my laptops it seems my batteries that i would allow to discharge fully and charge full, then did not leave plugged in seemed to keep charge longer.

    http://www.techyv.com/questions/how-increase-laptop-battery-life

  27. JazzFanJake

    I got a Dell laptop for Christmas last year and as luck would have it, had to send the thing into the repair shop due to a corrupt hard drive. I think this was caused by random unnecessary crap which was hogging up system memory. Anyhow, I got it back not long ago and it seems to be working as good as new. I leave it plugged in unless I am somewhere else and need it. But I’m a bit unsure which is best: starting the charge once the first battery alarm goes off, or after the second alarm. Also, prior to sending it in for repair, I had a Dell power management scheme which no longer seems to be in the list. My laptop is as I said running fine, but I’m just curious about these things.

  28. Doh

    Nickel Cadmium had memory.
    Lithium does not.

    Most chargers trickle to keep a full charge.

    Best to keep full charge. Best to equalize every 5 to 10 charges.

    Source: built and maintained industrial batteries for 14 years.

    Average cost was 5000 – 8000$$ per battery.

    At those prices you need to know how to prolong them.

Enter Your Email Here to Get Access for Free:

Go check your email!