02-17-2017 12:50 PM
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  1. Tabish Syed's Avatar
    I posted this as a reply to a certain someone spreading false information but I see many people have this misconception that it is bad to leave your phone plugged in because it will "overcharge" or "explode" or "catch on fire" or something..... Some say "oh but battery widget reads 4.2v or 4.3v that is bad...." Here are the FACTS:

    1) New battery chemistry in modern phones is not 3.7 nominal volts and 4.2 volts charged. Instead it is 3.85v nominal and 4.35v charged. (For example in my galaxy note 4)

    2) Google CC/CV charge curves. When the battery is low, initial phase is high current but the curve changes once the battery hits a certain voltage and the charging current gradually drops until it hits 0 at full charge.

    3) Protection circuits monitor voltage, charge and discharge currents as well as battery temperature. Leaving your phone plugged in will not let the current or voltage exceed rated specs due to charging / protection circuitry in the phone and battery.

    4) Always keeping your battery below 100% (like say 90) will have negligible effects on increasing battery lifespan (and by then you will have replaced your phone long ago).

    So basically it is perfectly fine to leave your phone plugged in to the charger like you do with a laptop.


    Source: Research, experience with Hobby grade Li-Ion and Li-Po batteries/chargers.

    Galaxy nexus, Galaxy Note 2, Galaxy Note 4 all left overnight with zero issues and no noticible battery degradation.
    02-22-2015 05:51 AM
  2. calebleesdad's Avatar
    I'm not going to dispute the points you've posted and really appreciate the time you've spent to help others, but the one time I did leave my note 4 connected to the fast charger overnight I got a notification to disconnect the phone...something to the effect of "battery at 100% disconnect from charger". I have not seen this when connected to my laptop or desktop. I don't think my phone will explode but isn't this some warning from Samsung related to their batteries, perhaps?

    Since then I prefer to charge my phone in the morning as I get ready to leave. It charges up full quickly and doesn't stay on the fast charger past an hour at most.

    Posted via the Android Central App
    02-22-2015 07:15 AM
  3. D Android's Avatar
    I'm not going to dispute the points you've posted and really appreciate the time you've spent to help others, but the one time I did leave my note 4 connected to the fast charger overnight I got a notification to disconnect the phone...something to the effect of "battery at 100% disconnect from charger". I have not seen this when connected to my laptop or desktop. I don't think my phone will explode but isn't this some warning from Samsung related to their batteries, perhaps?

    Since then I prefer to charge my phone in the morning as I get ready to leave. It charges up full quickly and doesn't stay on the fast charger past an hour at most.

    Posted via the Android Central App
    I agree with that. There must be a reason why the phone tells you to disconnect the charger when battery is fully charged and you will get the same message even when connected to the laptop, just takes longer to get to 100%.
    02-22-2015 07:43 AM
  4. clevin's Avatar
    Jesus, you have no clue what you are talking about and blatantly misleading people here.

    You completely ignore the laboratory test results with real, precise measurements, and based your false statement on your own " Research, experience with Hobby grade Li-Ion and Li-Po batteries/chargers. "? Jee, with your method, who need science?
    N_LaRUE likes this.
    02-22-2015 07:45 AM
  5. Kamau's Avatar
    I'm not going to dispute the points you've posted and really appreciate the time you've spent to help others, but the one time I did leave my note 4 connected to the fast charger overnight I got a notification to disconnect the phone...something to the effect of "battery at 100% disconnect from charger". I have not seen this when connected to my laptop or desktop. I don't think my phone will explode but isn't this some warning from Samsung related to their batteries, perhaps?

    Since then I prefer to charge my phone in the morning as I get ready to leave. It charges up full quickly and doesn't stay on the fast charger past an hour at most.

    Posted via the Android Central App
    Probably more of a reminder than a warning. I've seen it on other phones when it's reached 100 percent.
    ToddK and Stwutter like this.
    02-22-2015 07:46 AM
  6. ab304945's Avatar
    I have left my s5 on the charger over night, every night since July. And have no battery issues.

    The same with my s3 i had for 2 years with no problems

    Posted via the Android Central App
    02-22-2015 08:14 AM
  7. Mojofilter9's Avatar
    The phone comes with a removable battery, why would anyone care about something that *may* marginally decrease performance over an extended period of time??

    Charge your phone overnight because that's clearly the most convenient was of doing it, worst case scenario is that you have to spend £15 in 12 months time.


    Sent from my iPad using Tapatalk HD
    02-22-2015 08:16 AM
  8. worwig's Avatar
    Also, the battery is removable. That means that the battery pack also has protection in it from overcharging, under discharging, and over current. Plus of course the phone has those protections. It is double protected from damage. Leave it plugged in all night. Wake up to 100%. Win.
    The unplug message is just a reminder. If it was doing something important, it would be automated. LiIon and LiPo battery charging can't be left to 'I hope you see this message'.
    If you unplug it, the phone will operate from the battery. That will be cycling the battery. That WILL use battery life.
    I have a Surface tablet that reports battery wear. It is over two years old, and spends 90% of the time plugged into power and at 100%. The lithium battery pack is showing about 3% wear after over 2 years at 100% on charge. No issue there.

    But in the end, we buy these portable devices to meet OUR schedules. And in particular the Note has a replaceable battery. Do what works for you. Putting mine on a charger whenever I'm not using it works for me.

    Go to THIS well written article:
    Smartphone Futurology: The science behind your next phone's battery | Android Central

    Glance over the boring details if you wish and go straight to THIS: Tips for improving lithium battery longevity
    02-22-2015 09:30 AM
  9. hamsterwheel's Avatar
    I have always done this every night for any phone I have ever had with no issues at all.

    Granted with the Note 4, I use my BlackBerry charger which is not the "fast charging" one, but no issues with battery life at all.
    ToddK, brad419 and Stwutter like this.
    02-22-2015 09:38 AM
  10. jwt873's Avatar
    I've charged all the cell phones I've ever owned overnight for the last 15 years without any problems.

    Out of interest..... On page 186 of the Galaxy Note 4 (English) User's Manual it states:

    Avoid charging your device for more than a week, as overcharging may shorten battery life.

    So If leaving the phone on charge for seven days (168 hours) MAY shorten battery life... I think it's pretty safe to say taht leaving the phone on charge for 12-14 hours overnight won't really do any damage.

    Actually everything there is to know about changing is in the manual. Pages 16-18
    02-22-2015 10:01 AM
  11. scassel's Avatar
    Same as others...have charged over nite for years with no I'll effect. My take on the "warning" has been to remove the brick from the wall outlet more than remove the phone to spare the battery from "over" charging. It's the green thing to do.

    Posted via the Android Central App
    ToddK likes this.
    02-22-2015 10:36 AM
  12. Tabish Syed's Avatar
    Jesus, you have no clue what you are talking about and blatantly misleading people here.

    You completely ignore the laboratory test results with real, precise measurements, and based your false statement on your own " Research, experience with Hobby grade Li-Ion and Li-Po batteries/chargers. "? Jee, with your method, who need science?
    You present zero facts. Let's see this science you speak off.
    02-22-2015 11:37 AM
  13. Tabish Syed's Avatar
    I'm not going to dispute the points you've posted and really appreciate the time you've spent to help others, but the one time I did leave my note 4 connected to the fast charger overnight I got a notification to disconnect the phone...something to the effect of "battery at 100% disconnect from charger". I have not seen this when connected to my laptop or desktop. I don't think my phone will explode but isn't this some warning from Samsung related to their batteries, perhaps?

    Since then I prefer to charge my phone in the morning as I get ready to leave. It charges up full quickly and doesn't stay on the fast charger past an hour at most.

    Posted via the Android Central App
    Its just a reminder that the battery is done charging.
    ToddK likes this.
    02-22-2015 11:39 AM
  14. pappcam's Avatar
    I have used my phone as my night clock/alarm clock since the days of the BlackBerry Curve all the way through my S3 and Note 4 and I've never "damaged" or ruined my battery in any way.

    I'm also tired of misinformation being spread as fact on message boards but hey, it's your phone to do with what you want. If you want to take advice from anonymous people on the internet with absolutely no real world basis for their information, have at 'er.
    plumcrazy and ToddK like this.
    02-22-2015 11:49 AM
  15. AndroidHabit's Avatar
    I have always noticed and so have others, that when you leave your phone charging overnight, it lasts longer.
    Once the battery notification pops up and says to remove the charger, it is meant to save household energy.
    The phone will stop charging the battery through the night and only trickle charge if it falls below 100%.
    ToddK and mumfoau like this.
    02-22-2015 11:57 AM
  16. Tabish Syed's Avatar
    Same as others...have charged over nite for years with no I'll effect. My take on the "warning" has been to remove the brick from the wall outlet more than remove the phone to spare the battery from "over" charging. It's the green thing to do.

    Posted via the Android Central App
    You missed the point entirely ! It cannot overcharge. There is a cutoff once it hits a certain threshold (about 4.35v). The warning is not a warning. It's just a reminder that it is done charging.
    02-22-2015 12:22 PM
  17. jwt873's Avatar
    But there is a warning about overcharging in Samsung's Note 4 user manual... (See post #10 above)

    On page 186, it says "Avoid charging your device for more than a week, as overcharging may shorten battery life".
    02-22-2015 12:51 PM
  18. carlos12001's Avatar
    I've always kept mine plugged in overnight. Always will.

    Sent from my glorious note 4.
    ToddK likes this.
    02-22-2015 01:04 PM
  19. plumcrazy's Avatar
    But there is a warning about overcharging in Samsung's Note 4 user manual... (See post #10 above)

    On page 186, it says "Avoid charging your device for more than a week, as overcharging may shorten battery life".

    more than a week and "MAY" are very different than overnite and definitely will cause an issue
    ToddK likes this.
    02-22-2015 01:38 PM
  20. worwig's Avatar
    But there is a warning about overcharging in Samsung's Note 4 user manual... (See post #10 above)
    On page 186, it says "Avoid charging your device for more than a week, as overcharging may shorten battery life".
    Yep.
    It is a 'catch 22'. IF you leave it at 100% on charge for a LONG time, it will wear the battery a bit over a long time. IF you leave it closer to 50% it will last longer. BUT, when using the battery, you are wearing it out. In other words, if it is unplugged and near 50% you are wearing it out. So the only way to get long battery life is to pull it from the phone at 50% and store it. Impractical.
    In other words, if you are using the battery AT ALL, it is wearing it. If you plug it in and leave it for weeks, you are wearing it out. So use it how it fits your schedule. (Do avoid heat, that is a real killer, and it is practical to control that)
    But the point of this thread is valid. A lot of people think that an overnight charge is a horrible thing. It really is not, and in fact might be the best thing to do to get longer battery life.

    From my personal view. My wife often forgets to plug in her phone at night. She is often plugging in the phone only after it gives a low battery indication. I have always plugged mine in if I am near a charger and left it overnight. Her batteries appear to show a lot of wear after a couple of years and her battery life is poor. Mine after a couple of years are performing about as well as new.
    Of course it may also be that she yacks on the phone a lot more than I do.
    ToddK likes this.
    02-22-2015 02:19 PM
  21. Rukbat's Avatar
    IF you leave it at 100% on charge for a LONG time, it will wear the battery a bit over a long time.
    Wrong. Once it reaches 100% it stops charging.

    IF you leave it closer to 50% it will last longer.
    Wrong. If you're going to store it for long period out of the phone, 40% is about the optimal charge, because the self-discharge rate will be lower. You're mixing two totally different things.

    BUT, when using the battery, you are wearing it out.
    No, you're using it. A well-maintained lithium battery can last so long the phone it's in becomes unusable. (My V551 OEM batteries - over 10 years old - still give me about 95% capacity. They're about 20 years from being "worn out" and, at 72, I don't think I'll be alive by then - and GSM phones probably won't be used any more. [My StarTAC is still the best phone I ever had, probably the best one ever made, but you can't use one any more. No GPS.] Maybe in 20 years, phones will have to have something in them that we haven't even invented yet.)

    In other words, if it is unplugged and near 50% you are wearing it out. So the only way to get long battery life is to pull it from the phone at 50% and store it. Impractical.
    That's not long life, that's long storage. You still have to check the SoC every 3 months or so to keep it at 40%. Leave it for 5 years and you have a piece of hazardous waste, not a battery. (Lithium is a hazardous material.)

    I have always plugged mine in if I am near a charger
    Also not the longest life scenario. Charging the battery every time it drops to 90% will give you less total power over the life of the battery than charging it at 40%. (Carrying a spare battery - with a phone with a replaceable battery - is the easiest way to get the most out of your batteries. 40%? No charging capability? Swap batteries.)

    See the second figure (the chart) at Battery University - How to Prolong Lithium-based Batteries. Cadex has probably analyzed more batteries in 2014 than all of us combined on this forum have owned over our entire lives. What they don't know about batteries isn't known, it's still being researched (like how to prevent dendrites in lithium batteries - no one knows how to do that yet). If you want the expert word, take it from the experts.

    Tabish, my only argument with your original post is that modern batteries (manganese cobalt oxide positive poles and graphite negative poles) have a nominal voltage of 3.7 Volts, but they have a potential of 4.2 Volts while being charged, not "when fully charged". (As soon as you disconnect the charger, the terminal under load voltage drops to 3.7 Volts.) A lot of manufacturers currently charge their batteries to 3.85 Volts terminal voltage by holding them at 4.35 Volts during charging, but that shortens the life of the battery (while giving a slightly longer time between charges). Marketing has a lot of knowledgeless input to engineering these days. When the marketing VP says "this will sell more phones" and the engineering VP says "this will destroy more batteries", marketing wins out. Batteries that die after 6 months don't impact on the company's bottom line, selling more phones does.

    No one has invented a new sub-atomic physics yet - manganese cobalt oxide as a positive pole and graphite as a negative pole still gives the same voltage it would have given 10,000 years ago. What we need isn't futzing with existing technology, what we need is a light, power-dense battery that can take constant full discharges, and fast charges. A car battery is still FAR better than ANY lithium chemistry - except for weight. Lithium is the lightest metal, lead isn't. But they're working on it. There's an industry that's bigger than the cellphone industry that's screaming for power-dense, deep-discharge light batteries - the automotive industry. And they'r driving most of the research. A dendrite in the battery of a hybrid or electric car costs the company US$2,000. Put that huge, heavy battery into a box the size of shoe box and we'll see phones with 2 month standby/2 day talk battery times.
    brad419 likes this.
    02-22-2015 05:23 PM
  22. scassel's Avatar
    You missed the point entirely ! It cannot overcharge. There is a cutoff once it hits a certain threshold (about 4.35v). The warning is not a warning. It's just a reminder that it is done charging.
    I agree wholeheartedly. I chose my words poorly.

    Posted via the Android Central App
    02-22-2015 05:37 PM
  23. Tabish Syed's Avatar
    Tabish, my only argument with your original post is that modern batteries (manganese cobalt oxide positive poles and graphite negative poles) have a nominal voltage of 3.7 Volts, but they have a potential of 4.2 Volts while being charged, not "when fully charged". (As soon as you disconnect the charger, the terminal under load voltage drops to 3.7 Volts.) A lot of manufacturers currently charge their batteries to 3.85 Volts terminal voltage by holding them at 4.35 Volts during charging, but that shortens the life of the battery (while giving a slightly longer time between charges). Marketing has a lot of knowledgeless input to engineering these days. When the marketing VP says "this will sell more phones" and the engineering VP says "this will destroy more batteries", marketing wins out. Batteries that die after 6 months don't impact on the company's bottom line, selling more phones does.

    No one has invented a new sub-atomic physics yet - manganese cobalt oxide as a positive pole and graphite as a negative pole still gives the same voltage it would have given 10,000 years ago. What we need isn't futzing with existing technology, what we need is a light, power-dense battery that can take constant full discharges, and fast charges. A car battery is still FAR better than ANY lithium chemistry - except for weight. Lithium is the lightest metal, lead isn't. But they're working on it. There's an industry that's bigger than the cellphone industry that's screaming for power-dense, deep-discharge light batteries - the automotive industry. And they'r driving most of the research. A dendrite in the battery of a hybrid or electric car costs the company US$2,000. Put that huge, heavy battery into a box the size of shoe box and we'll see phones with 2 month standby/2 day talk battery times.
    That is not how it works! The cell keeps it's voltage at 4.2 or 4.35 (or whatever the charger stops at) even after charging is done.

    The voltage holds until a load is applied. The voltage drop is proportional to the load. Better batteries (for example with lower internal resistance) have a lower voltage sag under load. If the load is minor, the voltage sag will be minimal.

    I am not saying that physics has changed, but there have been advancements made and newer LiCo batteries are rated at 3.85 / 4.35 V instead of 3.7 / 4.2. This isn't just marketing. If you try to charge an older 4.2v lithium battery to 4.35, you will end up damaging it but newer cells are designed for this voltage. If what you said about marketing was true, then Samsung, Apple etc would be overcharging their lithium batteries which is not only stupid because it lowers battery life but also dangerous.

    PS: I just tested my Note 4. Battey at 100%, 4.3V. After removing the charger and with the battery under load and the phone at max brightness.....still 4.3V. After a while, 4.2V.

    If I used a cheap crappy chinese battery with a stupid high internal resistance, then the voltage would drop even more.

    EDIT: You might be confused about the voltage sag. If so, look up Constant Current / Constant Voltage (CC CV) charging which is commonly used in charging lithium batteries.

    This is different than constant current charging (I think car batteries are charged that way). Instead of a constant current then off, CC CV lowers the current gradually until charging current hits 0 at Vmax.
    02-22-2015 08:07 PM
  24. ChemMan's Avatar
    Does anyone have some real numbers to back up anything they are saying here?

    Get a data logger and plug the phone in with a dead battery and charge it up and draw the data points.

    I had actually done this manually and the results are in the table attached. I really don't think anyone needs to worry about leaving the phone plugged in even after the phone tells you to unplug the charger. The battery life is not going to change "very much" by leaving it plugged in overnight. It is a $30 battery and an $800 phone, think about it from the correct prospective. See attachment #2 for my professional opinion as a communications and electronics expert. Trust me, it will be fine.

    Battery myths. It is OK to leave your phone plugged in over night.-charg-note-1-.jpg

    Battery myths. It is OK to leave your phone plugged in over night.-calm2.png

    ps. Sub-Atomic physics aside, We can probably stick with standard old fashioned atomic physics here, No quarks are damaged in the charging of the Note 4. That I am sure of.

    lol
    02-22-2015 08:21 PM
  25. thomasv23's Avatar
    I always leave my phone plugged in over-night so I can have a full charge for the whole day and what not and I never ever have battery life issues
    02-22-2015 08:43 PM
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