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  1. #1
    LarWat
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    Default Portable Charging Banks

    Hi, I'm trying to find a charging bank that could recharge my phone a few times. Also, I'd prefer it to not weigh 20lbs but I do recognize these things arent light. Anyway, my big issue is that I have a Galaxy S20 Ultra. It has a 5000mAh battery and apparently prefers 15W charging output (more applicable in wireless situations as it just stops charging otherwise). I'm not great with this kind of stuff. All I know is the Powertraveller Harrier I purchased didn't even fully charge my phone once. Please help.

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  3. #3
    LarWat
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    Thank you so much!

  4. #4

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    Two charges to a 5000 mah battery operating at 5 volts on your phone from a power bank rated at 3.7 volts? You can't take a 10000 mah power bank and think it would charge your phone two times. 37 watts into a 25 watt battery..... You would maybe get 1.3-1.4 charges. Look for a 20000 mah power bank.

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    Quote Originally Posted by Big_Old_Dog View Post
    Two charges to a 5000 mah battery operating at 5 volts on your phone from a power bank rated at 3.7 volts? You can't take a 10000 mah power bank and think it would charge your phone two times. 37 watts into a 25 watt battery..... You would maybe get 1.3-1.4 charges. Look for a 20000 mah power bank.
    I don't follow this math at all, but I sort of agree with your conclusion, however you got to it!

    Basically, figure you can get about 70% of the mAH out of a battery into another battery (your phone), so a 10K mAH battery pack would be good for 7000 mAH into your phone, or maybe 1.4 charges, assuming your phone is near dead when charging. You might get two 30% to 100% top-offs though. Are you sure this isn't enough? A 10,000 mAH pack is about 7 ounces or so, a 20,000 maybe more like 12-14. That's starting to add up.

    I personally carry a 6700 mAH Anker pack (4 ounces), and that "fuels" my samsung S10 for 7-8 days pretty easily, basically two 30-100% top-offs of a 3500 mAH phone battery. And I use my phone for a lot of things (pics, navigation, kindle reader app, audio books, music), but nearly always on airplane AND battery saver modes.

  6. #6

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    btw you can operate your phone with a dead battery on those charger banks. no need to completely charge the phone. i only turn my phone on twice a day to conserve power when we go on long trips.

  7. #7

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    be sure the mAhrs of the charger is more than the phones battery mAhr rating.

  8. #8

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    Quote Originally Posted by colorado_rob View Post
    I don't follow this math at all, but I sort of agree with your conclusion, however you got to it!

    Basically, figure you can get about 70% of the mAH out of a battery into another battery (your phone), so a 10K mAH battery pack would be good for 7000 mAH into your phone, or maybe 1.4 charges, assuming your phone is near dead when charging. You might get two 30% to 100% top-offs though. Are you sure this isn't enough? A 10,000 mAH pack is about 7 ounces or so, a 20,000 maybe more like 12-14. That's starting to add up.

    I personally carry a 6700 mAH Anker pack (4 ounces), and that "fuels" my samsung S10 for 7-8 days pretty easily, basically two 30-100% top-offs of a 3500 mAH phone battery. And I use my phone for a lot of things (pics, navigation, kindle reader app, audio books, music), but nearly always on airplane AND battery saver modes.
    Powerbanks are rated by amps and at 3.7 or 3.8 volts. The NB1000 stores 37.5 watts.

    Cell phones and other devices use power at 5 volts. (power is voltage times amps = watts)

    A 10,000 mah (milli amp hour) powerbank cannot supply 10,000 at 5 volts, this would be 50 watts. (10 x 5). The bank only stores 10,000 time 3.7 volts = 37 watts. The powerbank outputting 5 volts yields only about 7,500 mah in theory but there are losses on the cables and other inefficiencies. So, you get maybe 7,000 mah out of a 10000....if you are careful when you discharge and you are lucky. Sorry if I cannot explain better. This person's blog probably explains it better

    https://blog.banggood.com/the-secret...0new%20voltage.

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    Quote Originally Posted by Big_Old_Dog View Post
    Powerbanks are rated by amps and at 3.7 or 3.8 volts. The NB1000 stores 37.5 watts.

    Cell phones and other devices use power at 5 volts. (power is voltage times amps = watts)

    A 10,000 mah (milli amp hour) powerbank cannot supply 10,000 at 5 volts, this would be 50 watts. (10 x 5). The bank only stores 10,000 time 3.7 volts = 37 watts. The powerbank outputting 5 volts yields only about 7,500 mah in theory but there are losses on the cables and other inefficiencies. So, you get maybe 7,000 mah out of a 10000....if you are careful when you discharge and you are lucky.
    Yep, the link does explain it, but one thing you say makes no sense; the statement "The NB1000 stores 37.5 watts". Watts are power (volts x amps), or rate of energy use, not storage which is simply energy. A watt-hour is energy.

    But yeah, amp-hours at one voltage (3.7) must indeed be converted to a lower amp-hour content at a higher (5) voltage, and it all now makes sense, simply 3.7/5, as you say.

    Basically if you had said "watt-hours" instead of "watts" it would have been clear to my simple mind. The NB1000 stores, ideally, 37.5 watt-hours.

  10. #10
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    Quote Originally Posted by colorado_rob View Post
    Yep, the link does explain it, but one thing you say makes no sense; the statement "The NB1000 stores 37.5 watts". Watts are power (volts x amps), or rate of energy use, not storage which is simply energy. A watt-hour is energy.

    But yeah, amp-hours at one voltage (3.7) must indeed be converted to a lower amp-hour content at a higher (5) voltage, and it all now makes sense, simply 3.7/5, as you say.

    Basically if you had said "watt-hours" instead of "watts" it would have been clear to my simple mind. The NB1000 stores, ideally, 37.5 watt-hours.
    The specs of the nb10000 are capacity 10,000 mah, 3.85v. 38.5Wh; rated energy 6400 mah

  11. #11

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    Quote Originally Posted by colorado_rob View Post
    Yep, the link does explain it, but one thing you say makes no sense; the statement "The NB1000 stores 37.5 watts". Watts are power (volts x amps), or rate of energy use, not storage which is simply energy. A watt-hour is energy.

    But yeah, amp-hours at one voltage (3.7) must indeed be converted to a lower amp-hour content at a higher (5) voltage, and it all now makes sense, simply 3.7/5, as you say.

    Basically if you had said "watt-hours" instead of "watts" it would have been clear to my simple mind. The NB1000 stores, ideally, 37.5 watt-hours.
    Ok, I was trying to make it simple for you, you obviously understand the matter. I was focused on helping with the math and to clarify that rated capacity of power banks is at 3.7 or 3.8 volts. Often, people are surprised when their 10,000 mAh battery does not deliver 10,000 mah into their phone. How many devices work off 3.7 volts? Not many. Phones and most electronics run off 5 volts, it seems deceptive and misleading of powerbank manufacturers although I understand why they are were they are. It is actually much more complex because capacity depends on temperature and load.

  12. #12

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    A li-ion battery tops off at a little over 4 volts, so a 5 volt supply is required to charge it as the charging electronics needs a bit more voltage to work. The minimum discharge voltage is about 2.7 volts, so in order to get a steady 5V out of the charger (or anything the battery is powering) something called a switching voltage booster is used. The effiecentcy of these run between 90 and 70 percent, depending on how much current is needed and how much the voltage needs to be boosted. Since power must be conserved, as the battery voltage goes down, the current from the battery must increase to keep the same level of current at the boosted voltage. So, as you drain the battery pack, it discharges progressively faster as power is removed from it. Say it takes an hour to go from 100% to 50% but it will take a much shorter amount of time to from 50% to 0.
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    Quote Originally Posted by Big_Old_Dog View Post
    Ok, I was trying to make it simple for you, you obviously understand the matter. I was focused on helping with the math and to clarify that rated capacity of power banks is at 3.7 or 3.8 volts. Often, people are surprised when their 10,000 mAh battery does not deliver 10,000 mah into their phone. How many devices work off 3.7 volts? Not many. Phones and most electronics run off 5 volts, it seems deceptive and misleading of powerbank manufacturers although I understand why they are were they are. It is actually much more complex because capacity depends on temperature and load.
    I was just being picky on terminology and units, and with the incorrect units I could not understand it initially. I finally got it and hope others get your important point too. I agree, I think the battery sellers are indeed being misleading.

    Very informative, thanks.

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