Top five laptop battery myths – which did you believe?

Laptop Battery life

A number of misconceptions about how long laptop batteries should last, and how you should look after them, have been circulating for many years, we tackle some of the most common below.

Battery life is a key consideration for many of us when buying a laptop, and ending up with one that runs down in a matter of hours is pretty annoying to say the least. A number of misconceptions about how long laptop batteries should last, and how you should look after them, have been circulating for many years – we tackle some of the most common below.

If you’re looking to buy a new laptop, don’t forget to check out our guide on how to buy the best laptop for you.

  1. Manufacturer battery life claims
    Laptops come with headline battery life claims from the manufacturer which sometimes sound a bit too good to be true, and, according to our testing, they definitely are. Our experts often find battery life claims that are hours longer than the real story when we put them to the test in our lab. For example, in a recent test the Acer Aspire Timeline U M3 claimed up to eight hours of battery life but we got less than five browsing the web over a wi-fi connection. Claims are normally benchmarked results given under specific circumstances – take them with a pinch of salt.
  2. Disconnect the charger when the battery is full or it will damage it
    In short, you just don’t need to do this – laptop batteries will stop charging when they are full. The battery technology used is much cleverer than it’s ever been before. Compared to 10 years ago say, you can now trust that you can leave your laptop plugged in and it will take care of itself.

    Laptop charger

  3. You need to let the battery drain completely before charging again
    Again, this is just not true. Like the above, this myth still exists from older battery technologies which are no longer commonly used. If you’re using your laptop at home you should leave the laptop plugged in making sure it’s running at full speed with the laptop battery setting on ‘high performance’ (see ‘Check your power setting’ in the tips below).
  4. Laptop batteries can always be easily replaced
    There’s no getting away from the fact that the running time on a single charge will get shorter over time. After a few years you might want to replace the battery, but it’s not always as easy as all that. On a standard laptop it’s generally possible to replace the battery – costing between around £50 and £100 depending on your model – and they’re easy to fit at home.Replacement laptop battery Ultrabooks however, tend to come with built-in batteries which you won’t be able to replace yourself and normally require you to send your laptop back to the manufacturer to be fitted – whether or not you’ll be charged may depend on if you’re within your warranty.
  5. Extended battery life claims
    Not exactly a myth, but these claims are worth looking out for as they refer to how long the laptop battery will last under very specific circumstances (some might say rather unlikely ones), as opposed to the ‘normal’ claimed battery life. You might see battery life claims of weeks, or even up to a month on some laptops, most likely on ultrabooks. The Asus ZenBook UX31E, for example, claims up to two weeks of ‘standby time’ with open files and other data kept safe in the memory. While the Acer Aspire S3 claims to conserve battery life for up to 50 days in Sleep mode. Though you can expect a longer battery life in sleep mode, the exact times claimed should be viewed with caution in terms of how they’ll stand up in a real life situation.

Getting the most out of your laptop battery

  • Check your power setting – your laptop should automatically switch to a power saving option when you’re running on battery but it’s worth checking. In Windows 7 or Vista check you’re not on a ‘High performance’ option in the Power Options settings – this can be used when using a power point but if you’re using the battery ‘Balanced’ or ‘Power Saver’ are more suitable, though the latter may affect overall performance.
  • Lower the screen brightness – this will reduce the rate of your battery’s power consumption. Brightness buttons will be marked with a sun icon.
  • Switch off wi-fi and bluetooth – turning these connections off when you’re not using it can improve battery life.
  • Eject CDs and DVDs – the spinning disks can eat up battery power so avoid using them when away from a power point where possible.

More on this…

Categories: Computing Helpdesk, Laptops

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31 replies

  1. I’d be interested to hear, ref point 4, if you think it’s OK to use replacement batteries from other than your laptop’s manufacturer.

    Ref point 5, are you saying that it’s no longer necessary to fully charge/recharge new batteries several times to get the best out of them?

  2. I replaced the battery in my very old (7 years) Dell Laptop after it stopped charging with a replacement battery from a batery specialist on line, with no problem at all. As it was a bigger battery it’s a whole lot better!

  3. Hmm, are you definitely sure about modern batteries having no ‘memory effect’ as they used to (i.e. if you don’t let the battery drain completely from time to time, it will ‘remember’ the lowest it has drained to and not work below that level). I still see advice on very recent devices such as smart phones and cameras that tells you to not keep the battery constantly topped up. Would be interesting to find out an ‘official’ view on this from a Lithium Ion battery manufacturer.

    Personally I still believe that keeping a battery constantly topped up will shorten its overall useful life and not allow it to hold as much charge. But I would love to proved wrong.

    1. Hi abmscopes – this is the advice of our Which? laptop experts and testers. I’ve also triple checked this with a well-known laptop manufacturer and they’ve confirmed that the in new style lithium batteries the memory effect has been reduced, so there is not the same affect as on older batteries to not letting it fully discharge/recharge over a period of time.

  4. I have seen batteries fail in many laptops, cordless phones etc. when people leave them permanently connected to the mains power. Have you noticed that newer products have the battery built into the product so the user can’t replace it?

    I’m not convinced that today’s battery technology is that much better. Best you unplug equipment from the mains the moment the battery is fully charged.

    1. That’s why I have just become an ex-Nokia fan after 11 years of loyalty David.
      I have a set of Nokia headphones that cost a not-insubstantial fifty-three quid. They are just over 2 years old now and the inbuilt battery will only power the headset for approximately 90 minutes now compared to 7 – 8 hours when they were new. Nokias’ official answers to this are that the warranty has expired, the headphones are obsolete now and that I should discard them and buy a new set. No tree-hugging green credentials there then!

      Up to this point I had been considering upgrading my Nokia N97mini to the Lumia 900. The former has a removable/replaceable battery but on the 900 it is integral.
      Taking into consideration the way I have been handled by Nokias after-sales department I don’t think I will be bothering with the 900 as I suspect that they will inform me in 2 years time that I should also send the 900 to a landfill site.

  5. I ALWAYS work on mains when doing something important like complicated updates. Ironically its the battery that supplies the backup, when the power lead falls out !

  6. I like to use my laptop, in this case acer timeline ultra like a desktop, while I can’t remove the battery, can I leave the charger plug on the power point all the time or should I use the battery energy everytime my battery is full? Notice that my battery is built in type. Thanks

  7. The replacement laptop battery market is a minefield. Finding genuine OEM batteries seems close to impossible – and the quality of many replacements is alleged to be very poor. I have found finding a good replacement extremely difficult.

    We need some assistance on this and a feature and some tests would be timely

  8. As per Mike above, finding genuine OEM batteries and or a reputable source of after market batteries is incredibly difficult. One supplier I found purported to sell OEM via EBAY and Branded via Amazon – when asked about the different in their batteries they ducked the question completely.

    It would be great if Which? could provide some research in this area – probably help avoid any potential safety concerns too.

    Many thanks

  9. Is number 2 correct?

    I have a Samsung ATIV BOOK 4 notebook which has built in batter(non-removable)
    Since i use laptop 90% of time at home
    is it ok to plugged in while using?
    does it damage the battery when always plugged in?

  10. Does continuous use of laptop battery beyond its lifespan affect the performance of the machine? ie does it affect the speed at which emails upload or documents open and close?

  11. If it is of any interest, has no one noticed, you can run a laptop of the mains without a battery.
    It means it is not portable, but a good tablet is lighter and easier to carry. They don’t do every thing but the laptop does.

  12. Where does one get the term ‘the battery has fried’ from then if leaving it pluggged in isn’t actually doing any damage? My mum had her laptop for well over 3 years, ALWAYS had it plugged in. NEVER unplugged it. And now it won’t run for very long without the mains plugged in. The same with my friend’s laptop. She insists that it’s because the battery is fried. Just how old do these laptops have to be in order for this to even happen? I’m so confused.. lol

    1. All batteries have a limited life, depending on the type of battery, its quality of manufacture and how it has been used (and/or abused). Leaving a battery permanently on charge and never discharging it is a fairly pointless activity and probably won’t maximise the service life of the battery.

      If a battery has failed, one might colloquially describe it as “fried” even though it may have been nowhere near the kitchen, let alone the frying pan. The use of the term “fried” for batteries probably comes from motoring, where the failure of a voltage regulator will allowvarious nasty things to happen to a car-type lead acid battery, including all of its acid “boiling” away, leading to a failed (“fried”?) battery. I think this kind of fault is much less likely to happen on a laptop.

    1. “mains” or “electricity mains” (as opposed to “gas” or “water” mains) is standard British English for a utility supplied domestic electrical system. Here in the UK, our system is 240V and 50 Hz AC.

  13. Batteries do degrade over time
    There are two different effect here:
    1) the ‘memory effect’ which used to be a feature of NiCd batteries. This isn’t observed in never batteries so you don’t need to heavily discharge then charge them.
    2) Wear out. The battery slowly losses it’s capcity and the laptop runs on battery for short and shorter times.

    In my experience the second effect is made worse by leaving the battery in the laptop when running on mains – it could be the constant charging, or even just that it’s always hot.

    My Dell laptop battery expired after about 9 months. I bought a replacement but swapped it with the old one when I was running on mains for more than a few minutes (or changing the battery). The replacement has lasted 4 years!

    My advice – don’t leave the battery on charge if you can avoid it.

  14. I’m inclined to agree with the original poster. There is probably variation across different brands, models, etc, but my experience with an Acer Aspire Timelinex 4820T is that after owning it for 3 years, it is left on (I use as media server for 2-3 hours a day), plugged in all the time, and very occasionally (say about once every 2-3 months) use on the battery, and it is …perfect. I now only get about 3 hours web-browsing on the battery, which is to be expected. Incidentally in case you think “why didn’t he just get a desktop ?”, I need the portability like I said every 2-3 months. I shut down completely, and take it out, and thereafter get the roughly 3 hours.

    I also think that if leaving it plugged in resulted in significant battery degradation, it wouldn’t be in the manufacturers’ interests anyway as there is so much choice out there to replace with, and so it would be relatively easy to have the battery on a separate switching circuit from the main power in.

    I’m so pleased with it that I’m inclined to get a replacement hard drive, battery and power adaptor now just in case they become unavailable before current ones give up. I have continually looked for my next laptop and can’t see anything that touches it for form, performance.

  15. are you serious. you know what. I remove my battery and depend on AC source because I thought Keeping the battery in will make its life short. you know what I mean. seriously? and how do we know that our laptop has this advanced technology any basis we can look on thanks

  16. I try to preserve my laptop battery by taking it out when the laptop is plugged in. It does improve the battery’s life span significantly. I usually wait until it’s fully charged to take it out because storing a battery when it’s empty might damage it irreversibly. One catch with this solution is you have got to make sure not to accidentally unplug the AC adapter. Since there is no internal power source you will lose all your work progress if the adapter is unplugged when your laptop is running. But if you are not moving around as much as I do, this shouldn’t be a problem.

  17. purchased a HP Chromebook in January 2014, the battery has now stopped charging completely. think it is not removable have re-charged but rarely left it plugged in once the charge was complete, seems to me this is such poor performance, think I will stick to my desk top from now on. I am a 78 yea rold pensioner and can’t afford to keep replacing items like this.

    1. Sue- your laptop is still under warranty if it’s under 12 months old, so you should be able to take it back to where you bought it from. Or failing that, contact HP and give them the details of where and when you bought the laptop. If the warranty was registered with them by virtue of the first time setup you went through, you can get them to handle the warranty even if the retailer isn’t able to. I did this with a laptop when the disk in it died 2 weeks before Christmas… and the laptop had been bought before Christmas, by a relative, as a present.

  18. OK . so what is the answer? Do i leave my laptop connected to the mains once the battery has charged or disconnect it.In other words, is it detrimental to us a laptop on mains with a fully charged battery?

  19. Hi, I’ve just bought a new HP laptop which claimed to have 8 hour battery but after a full charge it’s predicted run time was not even above 5 hours. I’m not sure why this is, are you able to shed some light on this situation?

  20. my new acer lap top when shut down/switched off, and unpluged, the battery loses its charge from fully charged to “dead as a door nail” in just over a 24hour period. the shop/dealer say they can not fault it. its been happening since the day i bought it 2 weeks ago. if i remove the battery when it is fully charged there is NO loss of power from the battery. help!

    1. That looks to me like your battery is holding charge well but that something ain’t right when you shut your laptop down. It could either be that you default shutdown state is merely some sort of low power sleep state or it could be that you have some sort of short circuit on your motherboard that is allowing the battery to discharge when in place. If the latter, you definitely have a fault that needs sorting under warranty – or even better reject the lap top and get your money back.

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