1. Rukbat's Avatar
    You've had your phone for 7 months, but the battery isn't holding up all day, the way it did when it was new. It's out of charge by 2 or 3 in the afternoon now. What's going on? Is this the bad battery life you've heard about this phone? Or was it the update you got 2 months ago?

    Neither one, actually. If you're like most people, you had the phone set up in the store, took it home and started using it. When it told you to charge the battery, you plugged the charger in. When it was fully charged you used it, waiting to charge it again until you got the message to charge it again.

    In most phones, that message comes at around 5%-10% of charge. Discharging a lithium battery that far will give you a lifetime of about 300-500 charges, but the battery will start losing capacity long before that. So after 150 charges you're noticing that loss of time until it has to be charged again. Maybe not much, but it used to last until you got home from work, now it's crying for its charger before you leave work. Maybe 5% loss of capacity, but a forecast of things to come. By the end of a year, you believe the stories that this phone damages batteries.

    The battery may have been sitting on a shelf at the battery manufacturer's plant for a few months after it was made, starting at about 40% charge. By the time it got to the phone manufacturer it was down to 35%, so they put the battery into a charger, brought it up to 45%, checked the phone to make sure it worked with that battery, turned it off and packed it up. Then it sat for another few months before you bought it. So far, so good. 40% is the right charge level for long term storage - both manufacturers know that - so the battery should be fine. (Lithium batteries discharge just a bit just because of the chemical makeup of the battery - it's caused self-discharge. [Most battery chemistries have that "problem", which is why the AAA batteries you buy in the store have expiration dates.] Just sitting on a shelf. The more charge in the battery, the faster the discharge. But if the charge gets too low, there are chemical changes taking place that shorten the life of the battery. 40% is about the best point. Low enough so the self-discharge is pretty slow, high enough to not shorten the battery life much.)

    Now you get the battery and start using it.

    Normally, you want to charge the battery until the phone says it's charged, then another half hour. Why another half hour? The only way to measure the state of charge (SoC) of the battery is to measure the voltage at the terminals when there's a load on it - like your phone. But that's an approximation, and if the phone is turned off it's drawing so little current that it's not really a load, so the battery seems more charged than it is. Even if it's turned on, giving a more exact picture, the charger is putting more voltage on the battery terminals than the terminal voltage of the battery at full charge. It has to. Current flows due to the difference in voltage. If the battery is at 3.5 volts, and the charger is putting 3.5 volts across the battery's terminals, it'll never charge. So the extra voltage from the charger - the voltage that makes the current flow into a just about charged battery - makes the SoC look a little better than it actually is. That extra 30 minutes tops it off to a real 100%.

    Don't worry about overcharging the battery. The charging circuit in the phone can tell when the battery is fully charged. (You can't measure it accurately on a "what is it now" basis, but if you watch the change in voltage and temperature over time - which the charging circuit does - it can tell when the battery is fully charged. Then it shuts off. The charger is still connected, or the phone is still on the charging plate (and the indicator light on the plate, if yours has one, is still indicating that the battery is charging) - but it's not. Leave it "charging" for a few hours and it might actually charge for a few minutes, when the actual charge drops down to 99%. But I've left phones plugged in for months and the batteries were still fine. (In a cellphone repair shop, when the phone was so old that the customer really didn't want to see it again, but it still worked, we'd save it until we had a box full, then donate them to the local women's shelter network [a phone doesn't have to be on an account to call 911, it just needs a charged battery], but we'd plug in the charger to make sure we were giving them a phone with a fully charged battery. Then it would get buried under other things, and we wouldn't see it again for months.)

    Now you use the phone until it tells you to charge the battery, right? Wrong. Try to never (except, as you'll see later, during conditioning*) let the battery get below 40% charge. Letting it get below 50% is where the lifespan starts dropping. 40% won't shorten the life enough to matter. 20%? Half the life. 5%? The battery probably won't last a year. And I'm still using the batteries (always 2 - if the one in the phone drops to 40% and I have to have the phone running a few more hours before charging, I swap batteries) in my Motorola V551 that I had when I opened the box in 2004. I'm still getting about 95% capacity. And, aside from long-term storage, they've never dropped below 40%. The phone is pretty useless - it has a 640 X 480 camera and it has a contact list. And it can access the web and do email. It was a very innovative phone in 2004. Why do I still use it? If I'm going to be in a place where someone might "find" it (people don't actually steal, they just find things - in your pocket), or where it may get damaged, it's a lot cheaper buying a V551 (or equivalent) on Craig's List for $20 (and that's a ripoff - my Samsung Precedent - an Android phone running Gingerbread - isn't worth more than that) than replacing a "found" Note 3. If I'll be in an area where the phone could get damaged, could get wet (but see Oh, no! My Phone got Wet!), and I still want to have a phone with me (I'm 72, you never know), I'll take the V551 with me. But I check the batteries every few months, and keep them around 40%. They're over 10 years old, and still ticking.

    In my daily driver (my Note 3), I switch batteries every month. On about the first of the month I fully charge the battery in the phone, take it out and put the other one in. Then the one that was in the phone becomes the spare. (NEVER carry a battery in a pocket or purse with the terminals bare. A lithium battery with 2000mAh capacity has enough energy in it to weld your keys to your leg. At least keep the battery in a baggie, if you don't have a small plastic case a little thicker than food wrap bags to keep it in. [If you buy a spare battery, they sometimes come in little soft plastic cases. Keep that case.]) One month, BTW, isn't considered long term storage. The battery will lose about 2% charge if you never use it that month, which is fine. Just put it into the phone, you'll see a 98% charge, and use it.


    When a battery has been sitting on the shelf for a long time (or if you don't know how long it's been on the shelf, like a new battery, or the battery in a new phone), you should condition it. (Some experts, and I'm not using the word facetiously, will tell you that modern lithium batteries don't need conditioning; others, just as expert, will tell you that some still might. It shortens the life of the battery less than having it in an outside coat pocket in sub zero weather for an hour**, so there's no reason not to, and there may be a good reason to do it, so do it.)

    Charge the battery full (100% plus 30 minutes). Use the phone until the phone tells you to charge the battery. (If you can't right then, swap in the spare.) Charge it to 100% again. Do 3 full cycles of full charge, wait for the warning to charge. After than you can drop it to 40% before charging. (Charging it when it doesn't need to be charged is just wasting time and power.)


    You're out in the cold. It's winter in central Alaska (people in Miami consider 80 degrees "cold"?) and the temperature outside is minus some double digit number. You're fine. Two pairs of wool socks, insulated boots, thermals, a 100% down parka. But your phone is in an outside pocket. (You're not going to unzip your parka in this weather to get your phone.) The gel electrolyte in the battery is close to becoming a hard solid. The phone rings. You answer it. The battery, which was fully charged when you left your house, goes dead in 5 minutes. Huh?

    Batteries are much like people when it comes to temperature. They function best at about room temperature. By freezing (32F, 0C), they've lost about half their capacity. It's linear - if the battery still worked at about -10F (lithium batteries stop working at about -4F), it would have no capacity at all. It's temporary - warm the battery up (assuming the gel in it didn't freeze into crystals that damaged the battery) and it's still good. But using the battery when it's cold - even just having the phone turned on - can lower the capacity dramatically.

    High temperatures are also bad. If the phone shows a high temperature warning, turn the phone off. If the battery comes out, take it out until it cools off. (It's possible for a lithium battery to go into thermal runaway - it gets hot faster than it can radiate the heat away, making it get hotter, making the situation worse, etc., until ... If you're lucky, the battery covering bursts into flame and you've lost $15. If not, and the pressure inside the battery builds enough, the battery explodes. The two places you don't want that happening are in your pocket and upwind of you. (Why upwind? A burning lithium battery produces very irritating smoke, and you don't want to breathe it.) This is why I will not buy a phone without a removable battery. I'd rather watch a $15 battery burn than watch a $700 phone melt. Battery damage to the phone normally isn't covered by the warranty. (Sony had to eat a lot of batteries due to a defective batch, about a decade ago.)

    Oh, on the subject of danger, while modern lithium polymer batteries can be safely disposed of in landfills (the most dangerous component is cobalt, and there's not much in a battery), please don't. There are many places that accept batteries for disposal. We throw out enough junk every day. Dropping a battery in a store's battery disposal bin isn't that difficult. (If the battery isn't removable, you're probably going to have it replaced by a repair shop if it needs replacing, so don't worry about it - they know how to dispose of batteries.)

    Just to put two myths to rest here.

    Myth 1 - "Calibration"

    You'll see that doing a single conditioning cycle (draining the battery very deeply) will "calibrate" the State of Charge indication (the 75% or whatever number you see as the current state of the battery). It won't. It has nothing to do with that. Calibration affects a file - the one that keeps track of which app is using what percentage of the current being drawn from the battery. After 10 charges or so, that file is pretty well calibrated. You don't have to do anything to make it as accurate as it's going to get. You're just wasting battery longevity.

    The indication doesn't seem to be right? That's because it's an approximation. The actual SoC can only be determined by analyzing the chemicals in the battery. The battery stores chemical energy, so its SoC is actually its "which chemicals are present in what percentages" state. Measuring the voltage across the terminals of the battery with a load on it (which is what you're seeing with the "state of charge percent") is the best we can do, so that's what we get. If it's off, that's because your battery isn't following the standard voltage vs. charge curve, and that's due to the chemicals in the battery. You can't "correct it". If it's that important to you, get the battery replaced. (It's not important - if you recharge at 40% or thereabout, the battery will have a long life. If it's actually 42%, it doesn't matter. [If it's bad enough that the battery is at 10% charge when it's indicating 40%, the battery is at end of life, so you need a new one anyway.])

    If you really want to calibrate the reading the phone has to be rooted, because a system file has to be modified to contain the voltage that's "100%" for that battery in that condition. Use Battery Calibration (Root) and follow the instructions contained in the app. (Conditioning the phone doesn't recalibrate anything although, in some phones it resets the % used graphs, so it appears to have done something to the battery.)

    Myth 2 - Charging a battery from 0 to 100% in minutes (or other "fast charge" nonsense)

    Lithium batteries can be charged at a 1C rate - IOW, the capacity of the battery. So if you have a 3200mAh battery, it can be charged at 3200mA (or 3.2 Amps). The charge from 0 (which you should never do to a lithium battery) to 100% will take an hour plus inefficiency (turning electrical energy into chemical energy - charging - is very inefficient), which means about 90 minutes. The recommended charge is 0.75C, or 3/4 of the battery's capacity. So for the above 3200mAh battery, a "fast charge" would be 2400ma (2.4 Amps). Most phones are designed to charge at around 0.5C. Charging from 40% or 50% to 100% at 0.5C is a little faster than a 1C charge from 0% to 100%, so about 80-90 minutes.

    You CAN NOT make the battery charge faster by using a larger charger. Electricity isn't pushed by the design (or capacity) of the charger, it's drawn by the design of the load (phone, powerbank, etc.) If the phone is designed to draw 1200mA (1.2 Amps), that's what it will draw, as long as the charger can supply that much. Connect it to a 100 Amp charger and it'll still draw 1200mA. (Your house, if you're in North America, is a 100 Amp [or larger] "charger". A 100 Watt light bulb still draws just under 1 Amp.) The only way to get the phone to draw more current is to raise the voltage coming from the charger - and if you're lucky, all that will do is damage the phone to the point that you'll need a new motherboard. If you're not lucky you'll be able to toast marshmallows in the resulting fire.

    (These new "fast charge" phones just change the parameters inside the phone to draw more current [by raising the voltage fed to the charging circuit in the phone], so instead of a 0.5C charge, they're doing a 1C charge - usually from 0% to 40%, which - if you're treating the battery right - you'll never get below, so who cares? The ones that fast charge from 0% to 50% are giving you a "fast charge" from 40% to 50% - saving you a few minutes. I don't know about you, but I wouldn't let that be a consideration when I'm looking to buy a phone. And I'm 72 - I probably have fewer minutes left than you do. Even giving you a 1C charge from start to 100% won't cut the battery's life by more than a tiny faction of a percent, if that, but it will cut the charging time considerably. But charging at more than 1C is considered a destructive test, not a charge - you do that to see how long it takes the battery to fail at various charge rates - and it's usually a very short time.)

    Oh - one more myth - that apps that save battery actually save battery. There are very few apps that actually save any battery power - Greenify is one of them. Apps that "clean RAM" or "optimize" the phone use more power than they save. (I've recently [during May, 2014] run some tests on a few of the more popular ones, and didn't find one that not only didn't save power, but cost power - the charge lasted a shorter time running the app then after it was uninstalled.] Any developer who write an app that "cleans RAM" is a developer telling me that he thinks that Android runs the way Windows does - when,in fact, it runs just the opposite way. Windows likes as much free RAM as possible. Android wants as little free RAM as possible. (One of the Android developers explains why at Multitasking the Android Way if you're interested.) If you want to get on my list of "I won't bother to read the blurb on your app's Play Store page" list, write an app that cleans RAM. If you don't know Android well enough to know how wasteful that app is (in both speed and battery), I don't trust anything you write for Android. You have to know the environment you're writing for. (I've been earning my living designing code for over 40 years, but I have yet to write my first Android app - and probably never will. I don't even know the API for writing to the screen in Android. Turn me loose on a Windows machine and it'll wash your dishes and mop your floors. But you can't write an app for an environment you don't understand, and "clean RAM" says, to me, "I don't understand Android as well as someone who won't even attempt to write an Android app".)

    More "myths" I've seen posted on Android Central:

    There's no such thing as a new 3.8 Volt lithium battery, it's the same old nominal 3..7 Volt battery with a new label. If that makes you feel like the battery is worth more than some other manufacturer's battery, it did its job. But a volt meter will show that a fully charged 3.7 Volt lithium battery and a fully charged 3.8 Volt lithium battery have the same open-circuit terminal voltage. (There are lithium batteries that produce more voltage - but they're not used for cellphones.)

    You don't use a charger rated at "at least 4.35 Volts" - that's the voltage applied to the battery terminals by the phone when it's charging the battery. Phone chargers are nominally 5 Volts (which means that some of them are rated at 5.2 Volts - and the phone really doesn't care). Make sure that the charger is capable of at least 1 Amp (or 1,000mA - same thing, like 100 pennies or one dollar). The old 500mA and 750mA chargers will take longer to charge the phone - current phones are designed to charge from the wall charger at a higher rate than that. (Most chargers are rated 2 Amps these days. The difference costs the manufacturer less than the label on the charger, since most chargers are a couple of cheap parts in a plastic case - the cable and plug are a large part of the cost.)

    With Samsung phones (I don't know about others because I haven't connected wires inside other phones to see), if the charger isn't a Samsung charger, the phone is going to charge at the USB charging rate, which is about 450mA for USB 2.0 and possibly 1,000mA for USB 3.0 (depending on the phone). Samsung chargers are wired to tell the phone that it's charging from a wall charger, so it should draw more current.

    Live long and prosp... er, keep working.
    03-07-2015 03:43 PM
  2. B. Diddy's Avatar
    Is this going to be on the final exam, Professor?
    Golfdriver97 likes this.
    03-07-2015 05:58 PM
  3. Golfdriver97's Avatar
    Thanks Dr. Rukbat!

    From an AOSP M8
    B. Diddy likes this.
    03-07-2015 07:06 PM
  4. Rukbat's Avatar
    It's all palgiarized - from me. After 72 years with only one mouth and 2 ears, more came in than went out. (No doctorate, though, not even a Master's - I hated school.)
    burim2010, B. Diddy and RG57 like this.
    03-08-2015 01:08 AM
  5. UpTheDumper's Avatar
    So... New phone drop to "charge" level, charge to 100% plus 1/2 hr. Do this three times, and then never let it get below 40%? Why doesn't someone make an app that doesn't let you go below 40%? Like 40% with this said app is the new "dead".. better yet, why the hell doesn't the manufacture do this in the first place so it's impossible for someone to ruin a lithium battery?

    Posted via the Android Central App
    03-15-2015 03:56 PM
  6. Aquila's Avatar
    So... New phone drop to "charge" level, charge to 100% plus 1/2 hr. Do this three times, and then never let it get below 40%? Why doesn't someone make an app that doesn't let you go below 40%? Like 40% with this said app is the new "dead".. better yet, why the hell doesn't the manufacture do this in the first place so it's impossible for someone to ruin a lithium battery?

    Posted via the Android Central App
    Most will still advocate against conditioning; fast charge and discharge both lead to high temperatures and more than necessary wear. That said, three out of hundreds of cycled is negligible to most.
    03-15-2015 06:18 PM
  7. UpTheDumper's Avatar
    Ok, so what's the best way to preserve the life and power of the battery in my SGS5 active..

    Posted via the Android Central App
    Techno-guy likes this.
    03-15-2015 06:53 PM
  8. B. Diddy's Avatar
    It's not that you can never let it drop below 40%--it's more that you should make it a habit to start charging at around 30-40%. The more often you let it drop to single digits, the shorter your overall battery lifespan will be. Since you have an S5 Active, you have a big advantage over lots of other people because you can replace your battery easily. So it's not as important for you or other owners of phones with replaceable batteries.
    04-16-2015 07:05 PM
  9. Neo_ii_Droid's Avatar
    Thanks for this PSA! I have to read that all over again, and slower than the first to fully absorb it.
    Golfdriver97 likes this.
    04-18-2015 06:17 PM
  10. RG57's Avatar
    Thank you for your excellent work, I have learned a lot. But I need one more piece of information: I will buy a new phone (exactly a samsung note 4) which will come with a battery full at a certain level, say 50% or 30%. To condition that battery, do I need to use the phone first until it drains the battery to 0%, or start right away charging until 100% + 30 mn. what ever it's remaining charge?
    Thank you in advance for your prompt reply,
    06-17-2015 07:17 AM
  11. Rukbat's Avatar
    Charge to 100% + 30 minutes (the moment the phone says 100% it's about 98% charged) first. Then use until the phone shuts off. Three cycles.

    Using it the first time probably won't hurt, because most phones these days come fully charged, but charging first can't hurt, and it probably won't take much time. (If you plug the charger in, turn the phone on and it says 100%, it came fully charged and you can skip the first charge.)
    Laura Knotek, d2008 and burim2010 like this.
    06-17-2015 04:12 PM
  12. Chitown28's Avatar
    I always set my phones up myself and charged them before i turned them on. I will take it out the box when i get home plug it up and let it charge for about 4hrs then i use it till it gets down about 10-15% and then charge it up again and keep repeating this cycle for a few weeks is this ok?
    Srdoug likes this.
    09-08-2015 12:03 AM
  13. Rukbat's Avatar
    Let it charge until the phone tells you to unplug it - then add another half hour. (The only way we have of measuring state of charge is a bit inaccurate - it says the battery is fully charged at about 98%.) Let it run normally until the phone tells you to recharge it. Repeat the cycle twice more - a total of 3 charges and 3 discharges. Then try to not drop it below 40%.
    burim2010 likes this.
    09-08-2015 08:17 PM
  14. Karl K's Avatar
    Thanks for the info! Finally found credible information on battery life. I still have a few questions though. I'm in conditioning now, using my phone until 5% and fully charging it. About the part of keeping over 40%, is it okay to charge often to do that, like when you're on 70%?
    11-28-2015 06:16 PM
  15. roshart's Avatar
    I have had my Samsung Galaxy S6 for three weeks now and have only just discovered that the battery should have been "conditioned" from the outset. Is it worth going through the process now, having just done the initial charge plus 30mins at the start. I haven't let it run down three times - has the level already been set now? I am amazed that no-one tells you this when you buy a relatively expensive piece of equipment for which you cannot replace the battery yourself!! Thanks in anticipation.
    01-24-2016 01:19 PM
  16. extraclass's Avatar
    I don't believe most of this!
    01-26-2016 02:04 PM
  17. rockshj's Avatar
    i have moto g3 from past three weeks.. how should i charge my phone.. for bttr battry lyf... nw a days m getting 6-7.5 hrs SOT
    02-26-2016 11:01 AM
  18. atzau's Avatar
    I have had my Samsung Galaxy S6 for three weeks now and have only just discovered that the battery should have been "conditioned" from the outset. Is it worth going through the process now, having just done the initial charge plus 30mins at the start. I haven't let it run down three times - has the level already been set now? I am amazed that no-one tells you this when you buy a relatively expensive piece of equipment for which you cannot replace the battery yourself!! Thanks in anticipation.
    ^^^ I'm in this situation as well... looking forward to finding out the answer.
    03-23-2016 01:01 AM
  19. FatiimaAch's Avatar
    So i should start charging at around 30-40% and let it fully charge to 100%, is that safe for the battery ? I have the samsung Note 5.please answer me
    03-12-2017 04:24 PM
  20. m0_onriver's Avatar
    very detailed.. thanks for the info sir
    06-06-2017 07:45 AM
  21. m0_onriver's Avatar
    does this mean, if your phone drops to 40%, you have to charge it till 100%?

    coz i've read a post from another forum, saying the sweet spot for lithium ion batt, is from 40-80%
    06-06-2017 07:49 AM

Similar Threads

  1. Battery issues after recent update?
    By chexx05 in forum Samsung Gear 2 & Gear 2 Neo
    Replies: 21
    Last Post: 04-14-2016, 05:35 PM
  2. Replies: 2
    Last Post: 03-08-2015, 04:51 AM
  3. Gs6 and gs6 edge
    By vegasdroid in forum Samsung Galaxy S6
    Replies: 4
    Last Post: 03-08-2015, 01:07 AM
  4. Replies: 1
    Last Post: 03-07-2015, 11:52 PM
  5. Why is the camera on my Sony Xperia responding?
    By Krumislav Barzov in forum Sony Xperia Series
    Replies: 1
    Last Post: 03-07-2015, 04:46 PM