How to get the most from Li-Ion batteries

How to get the most from Li-Ion batteries

Summary: Six tips for getting the best possible life out of the Li-Ion batteries inside your smartphone, tablet or notebook.

SHARE:
TOPICS: Hardware, Mobility
21

I'm sitting at my desk and I'm surrounded by devices that owe their lifeblood to Li-Ion rechargeable batteries. And as most devices are now built in such a way that replacing the battery is tricky – if not almost impossible – so you want to get the best possible lifespan out of that battery.

Battery from the iPhone 5S
(Source: iFixit)

How much of a difference can taking care of the battery make? Well, I have both a second-generation iPod nano bought around December 2006 and a first-generation iPod touch bought in 2008 that are both still on their original batteries and are still going strong.

So, how do you get the most out of Li-Ion batteries?

Understand the "recharge cycle"

Every battery has a finite lifespan, and this is given as the "recharge cycle" or "battery cycle." Put simply, this is the number of charge/discharge cycles that a battery can endure before being no longer fit for service. Many manufacturers offer this number. For example, Apple state that the iPhone battery is designed to retain up to 80 percent of its original capacity at 500 full charge and discharge cycles, while the MacBook Pro or MacBook Air is designed to deliver up to 1000 full charge and discharge cycles before it reaches 80 percent of its original capacity.

But most people think that they can dodge this charge and discharge by topping up their battery regularly so the battery doesn't get fully discharged. Unfortunately, you "cannae change the laws of physics." If you only let you battery discharge by 25 percent, then doing this four times counts as a cycle. Same if you do five charges after 20 percent discharge, or even 20 recharges after 5 percent discharge.

You cannae change the laws of physics!

However, what you can do is take advantage of this. How? By hooking your device up to a power source when you can. For example, playing music from your iPod or iPhone at home via a dock, or plugging your MacBook into a power outlet when convenient.

In other words, don't put the battery through unnecessary cycles. Understand that I'm not saying keep the device on charge all the time – that would also be bad for the battery because it needs a regular workout to keep its internal chemistry in good condition – just be aware of wasting cycles.

Full discharge vs. Partial discharge

Some people say that you shouldn't allow a Li-Ion battery to become fully exhausted before recharging, other people say it doesn't matter.

Truth is, with Li-Ion batteries it doesn't really matter because their discharge is closely regulated by on-board circuits.

This used to matter with the old NiCd battery chemistry because they could discharge completely and become impossible to recharge (those batteries also didn't like being charged too often, and were much more sensitive to temperature), and it matters with lead-acid batteries which also don't take too well to being discharged too much unless they are rated for "deep cycle."

Use the right charger

I'm a big advocate in using the right charger for the right device.

It might be more convenient to pack one charger and a bunch of cables for trips, but for long-term usage you're better off using a charger designed for your device because that's delivering the right amount of power for the battery. Regularly using a charger that delivers too much or too little power will affect the longevity of the battery.

If you are going to go down the third-party charger road, then make sure they are a reputable brand. No-name junk might look and feel like an original charger, but based on my testing I've found that what comes out of the cable can vary wildly.

Does it really make sense to hook up a $500 tablet to a $2 charger? I think not. While battery protection circuits do a good job of shutting off power that could damage a battery, poor quality chargers can still damage devices and the batteries inside them.

Keep an eye on the temperature

See alsoKeeping your iPhone, iPad and MacBook running in the cold weather

Room temperature – around 20°C/70°F – is the best temperature to charge equipment at. However, since we don't all life in climate-controlled rooms, we can extend this range out to 5 to 45 °C/ 41 to 113 °F. Anything either side of this and things can get bad for the battery. This is especially true for charging the battery at temperatures below 0 °C/32 °F, which can permanent damage the battery.

Subjecting Li-Ion batteries to temperature extremes can also physically damage the battery, causing it to warp or crack. This, in turn, can damage the device containing the battery.

Avoid physical stress

Drops and falls can damage batteries, causing it to leak a cocktail of corrosive chemicals, all of which are bad for electronics.

Long-term storage

What should you do if you plan on storing your device for an extended period? The normal instinct is to full charge the device, but I've found that only charging it up partially – around 50 percent – is the best way. Storing a battery in the discharged state can push it to the point where it won't recharge, and storing a battery fully charged can shorten its life.

Long-term storage is best done as close to room temperature as possible. So avoid really cold rooms or keeping the device next to a radiator.

Topics: Hardware, Mobility

Kick off your day with ZDNet's daily email newsletter. It's the freshest tech news and opinion, served hot. Get it.

Talkback

21 comments
Log in or register to join the discussion
  • New Li ion battery management technology

    There is, in fact, emerging Li ion battery management technology that will dramatically increase the number of charge cycles, see http://www.treehugger.com/gadgets/new-battery-management-technology-could-boost-li-ion-capacity-40-quadruple-recharging-cycles.html . The inventors have experienced some barriers to getting interest from the major players so far. While you can't change the laws of physics there are clearly ways where there things can be improved with a little smart thinking.
    1950graybeard
    • I bet so

      "The inventors have experienced some barriers to getting interest from the major players so far."

      - I bet they are running into a lot of barriers. No battery maker wants to see their batteries last beyond a certain timeline. The manufacturers will also be complicit with the battery makers because they will sell more devices. I had an HTC phone once that was less than 2 years old and the batteries were no longer being made. Kind of like how the auto industry squashed technology that increased fuel mileage. They all have their hands in our pockets to take the maximum they can get away with.
      fdhealy4
      • Right. Which explains why

        batteries today can handle 1000 recharge cycles and batteries ten years ago could handle about 250.
        baggins_z
  • Heat is the enemy

    When charging a dead battery for several hours, the battery becomes warm. Heat can degrade the chemical composition in the battery. Best to recharge the battery when device reaches 50%, so it takes less time charge consequently generating less heat. When is comes to li-ion its all about heat management to ensure better life.
    Sean Foley
    • Heat is the enemy but topping off is as well

      Recharging the battery before it discharges below 80% on a regular basis also stresses the Li-Ion battery.

      Laptops and such tend to do well when it comes to heat, they are typically operated in an air conditioned environment. However they are often left plugged in most of the time which does just as much damage.

      Cell phone batteries are exposed to greater extremes and tend to run hot when the phone is being used a lot.
      JPWhite
  • You cannae change the laws of physics!

    But it appears you can change the rules of arithmetic. I'd assume 5 x 20% = a full cycle, not 4x.
    DJL64
    • Ah yes.

      We all wish chemistry & physics obeyed our simple laws of math.
      SlimSam
    • Macbook Pro

      Incidentally, when my old Macbook Pro battery failed after a year and 80 discharge cycles, Apple told me I'd been using it incorrectly by keeping it plugged in most of the time. They did replace it though. Thankfully, it WAS user-replaceable, unlike the built-in battery in my new laptop.
      DJL64
      • Apple was right. You need to

        let your battery drain significantly at least once a week for optimal performance.
        baggins_z
      • Re: Macbook Pro. Battery....

        I am assuming the MacBook Pro was non Retina which is user serviceable.

        Two golden rules with Laptop Batteries.

        1) Never run a Laptop from the mains (except when charging). Keeping the Laptop constantly running off the mains kills the battery.

        2) Allow the Laptop Battery to drain entirely once a week.
        5735guy
    • 80%

      he was referring to the 80% charge level.
      Coincidentally that is the same as 4 x 20%.

      :)
      Steve__Jobs
    • Adrian didn't mean that

      He also said that doing 4 recharges at 5% counts as four cycles, too. What he meant to say is that the battery doesn't have to be exhausted to count a recharge as a full cycle, and it doesn't matter how fully charged the battery was before - it still counts as one cycle.
      goyta
  • Deep discharging can also affect availability

    All the neat things you CAN do with smartphones take battery power, especially if your home and frequented environment includes places with spotty coverage. This means the life of a charge can vary from all day (the best alternative being to plug into a bedside charger only while sleeping) to a couple of hours. Do you really NEED GPS all the time? If not, turn it off (Android phones provide a curtain-slide page to turn major subsystems on and off), and save both privacy AND power. Are you in a low coverage area during a time when you don't want calls? Turn off the cell/3G/4G/LTE radio, unless you need the internet and don't have (or want to use) wifi. Is there a "bogus" wifi hotspot that you cannot, or do not want to use, bugging you to connect? Turn off wifi for now. In your home, turn wifi on and make sure you connect to your own router. And one more thing: the industry has not found any better places to carry a phone than shirt/coat pockets and holsters. When your body blocks the signal, the battery runs down then also.

    The article also mentioned lead-acid batteries, which have a peculiar property, of which I was reminded by last week's Car Talk Puzzler. When completely discharged, they can be fully charged backwards! Since the plate construction is symmetrical, and the plates are differentiated only by the charge polarity applied at the factory, it is possible to hook up a charger to an isolated battery with reverse polarity and not notice any difference, but the polarity markings then become misleading. In the Puzzler story, the recharged battery was turning the starter motor in the wrong direction and thus not engaging the flywheel.

    That would be a real stupid mistake, or it could be a really nasty practical joke!
    jallan32
  • I dob't think so.

    "If you only let you[r] battery discharge by 20 percent, then doing this four times [sic] counts as a cycle. Same if you do it after 20 percent, or even 5 percent."

    Since when is that true? I know of no law of physics that requires that. Lead-acid batteries are an obvious exception. They last longest with shallow discharge cycles. (A single "full" discharge can destroy lead-acid batteries. I've seen it.) Whereas nicads seem to like heavy discharges.

    Li-ion batteries do seem to last a long time. I ascribe this to the use of an integrated charge system, tailored to the needs of the specific battery.
    GrizzledGeezer
  • Possible option for notebook used as desktop

    Since recharging is a lifetime limiter, consider limiting the quantity of recharge cycles by adjusting the low point (to trigger a recharge) at 50% or lower. While connected (or infrequently disconnected) the battery will wait to recharge until reaching 50%. This will reduce the cycle count, yet it still gives enough power for an unexpected meeting.
    SlimSam
  • only buy products with user removable/replaceable batteries

    i will not buy a product that has a battery i can not remove or replace myself

    i just checked online and found i can still buy a battery for my old palm 755p!

    my galaxy s4 has an aftermarket 4500 mah battery installed and i never carry a charger any more, i charge in the evening before bedtime every other day during normal use, usually at about 20%

    i do follow your advise on turning off unused/unneeded/unwanted features to extend battery life even more

    watching the olympic videos online is causing daily charging

    when/if this battery's performance fades, i will buy another

    the idea of replacing an item because it's battery failed is just plain stupid

    scott
    bmwr606@...
    • yup

      My Dell Venue 11 Pro has a user replaceable battery. It's one of the reasons I went with this particular model.
      dsf3g
    • Re: only buy products with user removable/replaceable batteries....

      As solid as that advice is the selection of products available with user replaceable batteries is relatively few in number these days with the exception of budget Laptops.

      As you stated "i just checked online and found i can still buy a battery for my old palm 755p" which just confirms replacing batteries on older Hardware is a lot less hassle.

      I have a 2013 Retina MacBook Pro. For battery replacement it would need to be sent off to Apple which is a pain as the battery is sealed in but that is my only gripe.
      5735guy
  • Charging power

    The article states "Regularly using a charger that delivers too much or too little power will affect the longevity of the battery". Any decent charging circuitry will only pull as much amperage as it needs, so plugging a device that needs only 1 amp maximum into a USB port capable of delivering 2.1 amps should have no negative effect whatsoever.
    lonniemcclure
  • longevity

    As far as I remember, LiIon batteries loose capacity about 20% per year when on 20 deg C and fully charged. This grows with higher temperatures.
    The best is to keep the battery as cool as possible and charged 30-40%. In this condition it looses about 1.5% when kept very cold (5 deg C) if I am correct.
    It's immanent in the chemistry.
    There are workarounds but I think it still applies to most batteries produced today.
    Miroslavr