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  1. Thread Author  Thread Author    #1  

    Default Question about charging your device.

    Ive done a bit of reading, and to confirm my observation, wall charging is twice as fast as USB charging. So that was good to know that i wasnt losing my mind.

    But my question now is, is any particular method better for the device itself? I know that charging it while off is best for the battery. but is charging it slower or faster of any noticible significance at all as far as the "wear and tear" on the battery life?

    My device is still new to me and was quite expensive so im trying to take the best care of it possible.

    Thanks in advance for any replies!
  2. #2  
    Greg C's Avatar

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    Default Re: Question about charging your device.

    Quote Originally Posted by pawprints86 View Post
    Ive done a bit of reading, and to confirm my observation, wall charging is twice as fast as USB charging. So that was good to know that i wasnt losing my mind.

    But my question now is, is any particular method better for the device itself? I know that charging it while off is best for the battery. but is charging it slower or faster of any noticible significance at all as far as the "wear and tear" on the battery life?

    My device is still new to me and was quite expensive so im trying to take the best care of it possible.

    Thanks in advance for any replies!
    It doesn't matter if it charges fast or slow. What matters is that you don't use a charger with more amps than recommended. Use a charger with the same amps as the one which came with your device.
    If my post helped you out...PLEASE be kind and hit the THANKS button.
  3. #3  
    kenorian's Avatar

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    Default Re: Question about charging your device.

    Not correct.

    If you have a background in electrical engineering or physics, this makes sense to you. P(ower) = I(current)V(voltage), after all.

    Current is PULLED, not PUSHED. If your 2A supply is connected to a battery that charges at 0.7A, it will still charge at 0.7A, regardless of the power supply capacity.

    Usually LiIon are specified at 1A max charge rate per 1000 Mhh capacity.
    Some few are rated at less - maybe 500 mAh and a few at higher.

    A system with a 2Ah battery will usually allow 2A max charge current. If your power supply supports up to 2A charging rate then at lower max charge rates time to charge will typically increase by a factor of LESS THAN Imax_possible/Imax_charger.
    eg a 750 mA charger will take LESS than 2000/750 = <= 2.66 x 2A rate.
    The reason that it will be less is that the initial part of the charge cycle is constant current and time is proportional to current, but the final part if at constant voltage with declining voltage, and the lower current charger may continue charging at its full rate during some or even most of this CV period.
    Example: Assume a device with a 2 Ah battery that charges at 2A until Vbat = 4.2V then at a constant 4.2V until I charge drops to 25% of Imax = 500 mA
    If a 500 mA supply is used instead then it may charge at full current until the current starts to fall, when charging is complete.

    The age of your device plays an important role, dictating both how fast it can be charged, and whether it can be charged using a wall charger at all. In 2007, the USB Implementers Forum released the Battery Charging Specification, which standardized faster ways of charging USB devices, either by pumping more amps through your PC’s USB ports, or by using a wall charger. Shortly thereafter, USB devices that implemented this spec started to arrive.

    If you have a modern USB device — really, almost any smartphone, tablet, e-book reader, or camera — you should be able to plug into a high-amperage USB port and enjoy faster charging. If you have an older device, however, it probably won’t work with USB ports that employ the Battery Charging Specification; it might only work with old school, original (500mA) USB 1.0 and 2.0 PC ports. In some (older) cases, USB devices can only be charged by computers with specific drivers installed.
    Treo 650 => Treo 700P => BB Curve 8330 => VZW BB Bold 9650 => VZW BB Bold 9930 => Droid RAZR MAXX HD => Samsung Galaxy S5
  4. #4  

    Default Re: Question about charging your device.

    Quote Originally Posted by kenorian View Post
    Usually LiIon are specified at 1A max charge rate per 1000 Mhh capacity.
    Some few are rated at less - maybe 500 mAh and a few at higher.

    A system with a 2Ah battery will usually allow 2A max charge current. If your power supply supports up to 2A charging rate then at lower max charge rates time to charge will typically increase by a factor of LESS THAN Imax_possible/Imax_charger.
    eg a 750 mA charger will take LESS than 2000/750 = <= 2.66 x 2A rate.
    The reason that it will be less is that the initial part of the charge cycle is constant current and time is proportional to current, but the final part if at constant voltage with declining voltage, and the lower current charger may continue charging at its full rate during some or even most of this CV period.
    Example: Assume a device with a 2 Ah battery that charges at 2A until Vbat = 4.2V then at a constant 4.2V until I charge drops to 25% of Imax = 500 mA
    If a 500 mA supply is used instead then it may charge at full current until the current starts to fall, when charging is complete.
    This is correct from my reading, and you may also see the charging/discharging rates listed as a "C" rating. A battery charged/discharged at a rate equal to its mAh reading is 1C. I.e. 1000mAh charged @ 1000mA (1A) is 1C. Li-ion batteries are typically rated at least 1C for charging unless otherwise specified. Charging slower than that is fine, but faster than that can damage the battery. The good news is every charging system I've seen for phones is pulling less than 1C, likely from the phone regulating the current regardless of battery size.

    Like my M8, with its 2600mAh battery. It can safely be charged at 2.6A for a 1C rating, but the OEM charger is rated at 1.5A. Also factor in the overhead of power just to run the phone without charging and you're looking at even less mA going to the battery itself. Even with plugging it into a 2.1A capable charger, it's still only pulling roughly 1.2A max and usually less than an amp according to monitoring apps like Gsam and Battery Monitor Widget. That shows that the phone dictates the amount of amperage to pull, and that higher rated chargers don't necessarily mean it'll charge faster.

    I do like higher rated chargers just for flexibility and potential longer usable life, but not for expecting it to charge a battery faster. Though as I showed above, you could charge a Li-ion battery much faster than our phones allow without impacting longevity. That would mean pulling the battery out and using a stand alone charger, and making sure not to charge over the 1C rating.
  5. Thread Author  Thread Author    #5  

    Default Re: Question about charging your device.

    So basically, if i only charge at the max that the battery can handle, or slower - it will not effect the long term battery life?

    Ive been using both the USB that came iwth it, and the charger that came with my samsung evergreen. but, when i got my new phone i double checked the brick part that came with the usb version, and the wall-only one that came with my toher phone, all of the numbers and symbols in terms of voltage are exactly the same. theyre both samsung so i had a suspicion that they might me equal, and they were. Its just easier for me to, since they were the same, leave the one in the wall, and leave the other in the USB port. then charging depends on where i am at the time. its more convenient that way. I just wanted to make sure if a slower charge was better in the long run or not. But, it sounds like it doesnt matter in my case, as long as I only use those 2 sources good to know!!
  6. #6  

    Default Re: Question about charging your device.

    Pretty much, but Kenorian was right about older computers and their ports being limited to 500mA. In today's higher powered phones, that may not be enough to power the phone and charge at the same time. It's possible you could see the battery level go down even while it's plugged in to a computer (or cheap, weak charger). Plus it means the charger has to work at full power while the phone still wants to ask for more, which can cause the USB port to burn out.

    Compare it to you vs an Olympic runner. You could run full pace and wear out quickly, while the Olympian could go just as fast but it's just a daily jog to him and could go on much longer than you too without breaking a sweat. That's the difference between a weak and strong charger.
  7. #7  

    Default Re: Question about charging your device.

    I've seen it happen like that too even when the charger is more than capable. In my case, it's not so much that the phone is using more than the charger can give, but heavy use by the phone is heating the battery too much to charge. Sticking the phone in front of an AC vent to keep it cool helps to allow charging while using GPS and other high demand activities.
  8. #8  
    Rukbat's Avatar

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    Default Re: Question about charging your device.

    Kenorian and Mooncat are correct but they left out one point. The faster you charge a lithium ion battery, the more change of dendrites forming. Well ... they're probably going to form if you charge a 4A battery at a 2mA rate - the jury is still out, experiments are still being done. But the faster you charge, the more likely large dendrites will form, and if you charge much above 1C, the chances are (again, experiments are still being done by the industry in an attempt to prevent this) that large enough dendrites will form to short the battery internally, thereby shortening its lifespan. (Not to mention bothering you by causing the phone to shut down, only to show a 40% charge when you turn it back on.)

    But, at the current time, using a 2 Amp charger on any cellphone should be just about as good for the battery as USB 2.0 charging (which is at a much lower rate).

    The only thing you have control over that's going to affect the total lifespan much is at what point you charge the battery. Assuming a well-conditioned battery (conditioning can't hurt a fresh battery, it can save one that's been sitting on the shelf for months), charging at the 40%-60% point (IOW 10% either side of half-discharged) seems to provide the longest life. See the charts at Battery University - How to Prolong Lithium-based Batteries
  9. #9  

    Default Re: Question about charging your device.

    Yeah, our phones are no where near being charged above 1C when charging within the phone. I do know some manufactures are selling batteries rated up to 3C in the R/C world of Li-ion (I have several myself) with no detrimental effects. So it's possible theoretically in phones too, but unlike R/C batteries that are charged on dedicated chargers, you have to consider the power requirements of the phone too unless you power it down during charging. With the phone running and also charging at 3C, you could easily be looking at 8-10A or more power draws. I don't know what the USB standard allows for max amperage, but I would question if a standard USB cable is capable of that much. Then you also have to take heat into consideration, both generated from charging and use of the phone.

    I have heard of Qualcomm releasing a new Quick Charge 2.0 standard that sounds pretty fast (I think I read something like 0% to 60% in 30 min, or something like that?) but it requires a special charger that's QC2 certified to do so, as well as a phone capable of detecting that type of charger being connected. The Note 3's OEM charger is rated at 2A and uses a USB 3.0 cable to handle the extra power from a computer with a USB 3.0 jack and it charges pretty quick. So technology is getting better for charge times.

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