charging my razr

Discussion in 'Smartphone Battery Discussion' started by eddiekeyton, Jun 19, 2012.

  1. eddiekeyton
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    eddiekeyton Member

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    i just got my razr yesterday so i dont know a whole lot about them. but i plugged my almost dead charger in at midnight last night. and uswd it while it was charging or lie an hr. then i tuned it off and went to sleep. at 4 am this mornin i checked it and it was only 80% charged. i fell back asleep and at 7 it was 99% charged. is it normal to take 7 hrs for a full charge while powered down and charging?

    Sent from my BLACK DROID RAZR using Droid Forums. Prepare to be impressified!!!!
  2. Adam74
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    Adam74 New Member

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    First, Congrats on the new phone! Second, Look in the battery subsection of the forums. A bright fellow by the name of Fox Kat is the battery whiz. Basically turn the phone off. Charge to 100%, discharge to 15% and turn phone off and charge back to 100%. What you saw at 7am and being at 99% is due to a multiple of conditions. In basic terms, the phone charges hard up to about 90% and then transitons into more of a trickle to prevent harm to your battery. Once it is at 100%, it stops charging again to prevent harm and your numbers will start to drop. Once it hits 90%, it will begin to trickle the juice back in. 99% can be attributed to a number of factors at 7am. My guess it was pretty darn full long before 7am.
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  3. eddiekeyton
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    eddiekeyton Member

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    understand that completely. ill update with how long ive been able to use the phone off of that charge. its been about 2 hrs and im only at 80 percent charge. is that pretty good? ive an avid user. barely ever see me without my phone in my hand.

    Sent from my BLACK DROID RAZR using Droid Forums. Prepare to be impressified!!!!
  4. FoxKat
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    FoxKat DF Super Moderator Staff Member Premium Member

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    There ^^^ is one fantastic member!! :icon_ banana:

    It's great to see people actually understanding the concepts that have proven time and time again to be accurate and crucial. I would follow this ^^^ member's advice to a "T".

    I will only add one thing to this. Avoid ever letting the phone reach near 0%. You should really make every reasonable attempt to get to a charger as soon as the phone indicates it's time to recharge, which for most phones is about 15%. If you know you're going to be away from a power source for a while and the phone is in the 15% region, it's best to power the phone off and wait till you can charge it again. Technically it's safe to use below 15%, and even more technically it's safe to allow the phone to self-power down at 0%, but in reality most phones' batteries are not in sync with the phone's metering system, so by the time the phone indicates the battery is at 0%, the battery may actually be at a voltage that is below the 0% cutoff (deep discharged), and this can result in bootlooping, powercycling, or (depending on how your LED works) in the case of the Droid RAZRs (RAZR, MAXX, and possibly other phones), the dreaded "White Light of Death".

    Bravo, Adam!
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  5. FoxKat
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    FoxKat DF Super Moderator Staff Member Premium Member

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  6. Adam74
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    Adam74 New Member

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    Now you're going to make me blush:p In all seriousness, I owe dang near all of my knowledge on batteries to FoxKat. i may simplfy it a bit, but I read the posts and apply what I learn. Thank you for sharing the knowledge so that people like myself can spread the word. :hail:
  7. Trash Can
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    Trash Can New Member

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    The 15% level.... please help me understand something that's been bugging me for a little while.

    It makes perfect sense that the only way to correctly set the 100% flag is to charge with the device powered off. I understand the possibility of a deep discharge -- that is, zero could be less than zero, but how can it accurately set the 15% flag (or 5% flag) if it doesn't know where zero is? In other words, could 15% really represent 25% (or 5%) as time goes on? Logically, it seems to me that it would need to know both values (100% and 0%) to correctly set any intermediate warnings. It seems like a catch 22 situation.... you don't want to drain it completely but there's no ideal way to accurately set the low level flags. Am I way off base or is this like picking fly crap out of pepper?

    Ready to start my Master's at FoxKat U. :D
  8. eddiekeyton
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    eddiekeyton Member

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    that is a good question. if you never let it hit zero how oes your battery know that 0 represents 0. if you charge constantly from 15% wouldnt your battery believe 0 is 15% thsmus losing that 15 percent of space in the battery. and over time your phone loses that 15% and thinks 15 is 0. then after a while loses 15% more. and so on. in time really weakening the batrery? i may not understand this correctly but as of right now that is what it sounds like to me. it really seems like nobidy is 100% on how to really mantain a healthy battery because there are all sorts of "theories". forgive me if im completely missing the point. im far from a battery expert.

    Sent from my BLACK DROID RAZR using Droid Forums. Prepare to be impressified!!!!
  9. eddiekeyton
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    eddiekeyton Member

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    also forgive my grammar. evidently my keyboard cant keep up with what i was typing lol. time to switch back to stock.

    Sent from my BLACK DROID RAZR using Droid Forums. Prepare to be impressified!!!!
  10. FoxKat
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    FoxKat DF Super Moderator Staff Member Premium Member

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    OK gentlemen, a great question and there's a relatively simple answer.

    This particular battery chemistry has a unique quality that bodes well for devices like ours. It provides relatively steady power at a range of voltages that is only a few tens of percentage points per hour of discharge from about 80% charge level all the way down to about 20% charge level. This is both good and bad. Electronics NORMALLY perform at different capacities depending on the voltages applied, however in computers they are designed to operate at the same level of performance across a relatively narrow range of voltages. Anything less is boosted up to the nominal required voltages, and anything more is truncated down to those same voltages. So, to properly power the motherboard for example, it requires perhaps as many as several different voltages, but the overriding voltage is 5V +/- 5%.

    The battery used in this device operates "safely" within a range of 4.2V down to 3.0V. Anything more stresses the battery, which is why the charger interrupts charging once the battery reaches the target voltage which results in a nominal maximum voltage of about 4.2V. It may actually reach a higher voltage during the end of the charging cycle, but after charging is interrupted, the battery goes through a "balancing" where the voltages "settle" down to the nominal 4.2V which is considered the maximum safe voltage for charge. It's easier to regulate the power to one voltage when the supply voltage remains relatively stable within a range, so for our purposes these batteries are a very good power source - but not perfect (yet).

    When using the battery, there is what is known as a voltage curve or line (depending on the type of battery and application). Imagine drawing a line that runs from the top of the 10 story building at one end of the block to the street level at the other end. You'd end up with a line that is we'll say diagonal starting high in the sky at one end of the block and ends at ground level at the other end. It would be nice if batteries discharged in such a straight line (Voltage) over that time frame (length of the block), but unfortunately they don't. Some are more straight than others, some have parts of their discharge cycle that look more like a free-fall than a gradual decent.

    In the case of Lithium Ion Polymer Pouch Cells (which is what we have in our RAZRs and MAXXs), it has a line that starts out high (4.2V), but drops pretty quickly (first 10% - 15%) down to a stable level (4V), then slowly declines from there to about 20% (3.4V), where it then starts to drop again quickly through the last 20% to the cutoff voltage (3.0V). This following chart shows this, but the chart was designed to show more importantly how to get the longest life out of a LIPO battery.

    You'll notice the charge starts off at a much lower voltage in this example, actually 3.8V, but you will also see the characteristic rapid drop of voltage over the early portion of use immediately after charge, and then you'll see after the long slow drop, the range called the "temptation zone". This chart is saying that if you charge to a lower maximum voltage - not the 4.2V that the phone reaches at 100%, but perhaps the 3.8V showing here, which would be about 75% of rated capacity, and then you only use it till it reaches the beginning of the rapid drop, the "temptation zone", you'll prolong the life of the battery significantly.

    Now for disclosure purposes, this battery is being heavily loaded in the chart to a rate of power consumption that will be much higher than the RAZR/RAZR MAXX phones will use, so the result for the phone is that the line would be MUCH longer from left to right. Also, this is for a battery that's about 42% of the size of our MAXX cells (1,400mAh versus for the MAXX 3,300mAh), and about 80% of the size of the RAZR batteries (about 1,780mAh or 79%), so the chart for our batteries would look comparable in Voltage but significantly different in Amperage. Finally, they aren't charging to 100% of rated capacity, but instead to about 80% (3.8V), so they are already preventing the stresses at the top of the charge, and the chart is telling you to also stay out of the bottom of the charge, to obtain the best ratio of lifespan with run times.

    Click on pic to see full-size.


    discharge_curves.jpg


    SO, we see that if the phone's charging system wants two easy values to set the flags at, obviously the first flag will be set at a full charge (100%) since that's what 99% of the users will do, but if the manufacturer wants you to start charging the phone at 15% (as it indicates on the screen when you get there), and to avoid the "temptation zone", then it needs to set the low level flag at 15%, otherwise it would never set the low level flag since the user would never let it discharge to say 10%, or 5%, or God forbid, 0%. In other words, if the low level flag was set lower, then they'd have to set the warning lower to match. They don't want you running in that "temptation zone", so what better way to *(hopefully)* convince you to stay out of there than to pop up a screen warning, bong and tell you to plug in?
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  11. Adam74
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    Adam74 New Member

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    That.... is a great question that i will have to defer on. ha! I am sure that between Foxkat, SallyC, or the 941 something rather (sorry, i forget all the exact names) there will be an answer provided. i also seem to recall a resouce by FoxKat of Battery University. They will know how it works with much specifics. Maybe it has to do with the bell curve describe on battery use? Maybe the drop is easier to calibrate? I'm really guessing and could be way off. Sorry if I'm way off....
  12. Adam74
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    Adam74 New Member

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    i see I was too late. Thank you FoxKat:hail:
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  13. FoxKat
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    FoxKat DF Super Moderator Staff Member Premium Member

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    Spot on...the bell curve, and the drop makes it easier for the meter to calibrate. :hail:
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  14. Adam74
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    Adam74 New Member

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    That is so cool!!!! Again, the only way I even had a clue was the resources posted in previous threads. I'm feeling a bit more smartical.dancedroid
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  15. diablo81588
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    diablo81588 New Member

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    Dude, your a genius. How did you learn all this stuff? Lol

    Sent from my DROID BIONIC using Tapatalk 2
  16. FoxKat
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    FoxKat DF Super Moderator Staff Member Premium Member

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    :rofl3: Really, I'm no genius, I'm just a research freak, deep though person, and a technogeek! More importantly, I love to help people and want to make sure they have the most beneficial and accurate information. It's so easy to be mislead by urban legends, just ask Penn & Teller.

    Thanks for the complements, but the biggest complement you can give me (other than this so public broadcast), is to convey this information to the masses and show solidarity so we can weed out the bad information for everyone. Also, please feel free to "Like" any posts of all members that you think have provided you with helpful information, or have helped someone else and you feel are deserving of your show of appreciation.

    Thanks again. Good luck! :biggrin:
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  17. FoxKat
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    FoxKat DF Super Moderator Staff Member Premium Member

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    I also didn't answer a part of that question so I'll attack it now. The thought that it would "lose" recognition of repeated 15% amounts and eventually "think" there's no capacity left makes sense if you only look at percentages, however the meter is looking at Voltages. Voltages will always be the same at the same relative "Charge Capacity". What does change over time is the actual capacity of the battery, so for instance a new battery may provide 15 hours of steady use at a certain level of power consumption before it hits 15% of capacity. A battery that's a year old however will only provide maybe 13 hours of steady use at that same level of consumption before it hits 15% of the now lesser capacity. In both cases, the 15% mark will be at the same voltage, let's say 3.35V, but what is lost is the length of time it takes to get from 4.2V (fully charged) to 15% (low battery).

    Another thing that's confusing for some is the % value itself. 15% of what, or 100% of what...?:blink: Well, it's a percentage of either the "rated capacity" (the number of mAh stamped on the battery), or the new, diminished capacity as a result of either time (batteries age even when not used and a 3-year old LIPO battery is essentially useless), number of charges, how it's been charged/discharged, and/or a combination of any and all of those variables. So a 1 year-old battery that's been abused by charging to 100% of capacity every time, kept at or in the range of 100% for extended periods of time (being left on charger for days as an example), allowed to endure high temperatures and always deep discharged (below 15%), may actually be as "old" as a 2 year-old battery that was cared for properly. In both examples, the two batteries may now have a capacity that is only 80% of the original "Rated capacity" as stamped on the battery. Still, both batteries will charge to their respective capacities and the battery meter will read 100% when they are fully charged, and as well will show about the same Voltage when they hit the 15% threshold, as long as the meter is in sync with the new - lower capacity.

    To simplify things, think of a glass that shrinks both over time, and with each fill, but shrinks faster if you either fill it to the brim, keep it full, or empty it. On the other hand it shrinks slower if you always leave about 10-15% of the liquid at the bottom, you don't frequently fill it to the rim, and if you do fill it, you begin drinking soon after. Also, even if you don't use the glass, it's slowly shrinking as well, so with each fill, it holds less in total. Is a glass that only holds 8oz any less full when it's full than one that holds 16oz? No, they're both filled to 100%, but one is 100% of 8oz, the other of 16oz. Likewise when there's only 15% left, the 16oz glass will have MORE liquid (2.4oz) left than the 8oz glass (1.2oz), yet they would both be considered 15% full.
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