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5 Things You Might Not Know About Powerbanks

Most people buy powerbanks based on indicated charging capacities. However, there are some details that we need to understand in order to maximize the use of these rechargeable batteries.

Powerbanks have become a huge secondary market commodity following the popularity of smartphones and tablets. It’s not a huge business that a lot of brands are coming out left and right.

In this quick guide, we explain why not all powerbanks are created equal.

1) Re-Charge Cycles and Lifespan. Powerbanks, like any other rechargeable batteries have a recommended recharge cycle. A good powerbank will have somewhere around 500 recharge cycles while sub-standard ones will have around 300 cycles only.

If you recharge your powerbank once a day, that means the lifespan can be somewhere between 300 days to 500 days. Once this re-charge cycle is fully consumed, the powerbank will no longer be able to re-charge to its usual capacity and degrades to about 50-70%.

2) Power Storage Capacity. Powerbanks cannot store 100% of the full power capacity that it states it can. Good ones can give you between 70 to 80%. Great ones like Anker powerbanks can go as much as 85-90%. That means if your typical powerbank says it can do 10,000mAh, the actual capacity could just be 7,000mAh.

This is called discharge efficiency and what is wasted or lost in the process is due to the internal circuitry of the powerbank as well as how good/efficient the batteries inside are.

3) Double A Batteries (cylindrical lithium-ion rechargeable). Most powerbanks use a 65mm AA-like re-chargeable batteries (18650, cylindrical lithium-ion rechargeable) connected in a series. These are easier to source, manufacture and assemble. That’s the reason why a lot of powerbanks have similar but odd-numbered capacities like 5,200mAh or 10,400mAh.

This is because they use multiple re-chargeable batteries (multiples of 2200mAh to 3400mAh) and not just one single large Li-Ion block. Some powerbanks which have thinner profiles do use a specific rectangular-shaped batteries like in smartphones.

4) Output Voltage and Output Current. The symbol mAh does not mean milliamps as most of us refer to but is actually milli ampere-hour and means measure of electric charge. One the other hand, Watt Hour (Wh) is a measure of electric energy.

The relationship of the two is shown in this formula:

milliamp-hour = watt-hour × 1000 / V


mAh = Wh × 1000 / V

The typical voltage for Li-Ion in powerbanks is 3.7V but output can go up to 5V. This is the reason why we see either of the two numbers in smartphones, laptops, or powerbanks.

The output current is measured in ampere which states how fast the current is passed thru the device. Most smartphones will use 1A while bigger tablets like the iPad might need 2.1A. Powerbanks have different ports for 1A and 2.1A while a fewer ones like Anker have intelligent sensing ports that auto adjusts the current depending on what the device needs.

Some phones like the Oppo Find 7 can handle up to 4A of current without damaging its internal battery.

5) Charging Cables. Charging cables are not created equal. Most cables have a data wire and a charging wire within the cable itself.

Typical charging cables are in the 28/28 gauge range with a wire diameter of about 0.321mm (first number represents the gauge of the data wire and the second number represents the charging wire). This is the reason why some cables could not charge phones or indicate slow charging.

We suggest getting a 28/24 gauge cable which are thicker. The 24 gauge ones are about 60% larger in diameter (0.511mm) and can handle 2amps of current. Of course, the cables can only transmit the same amount of power as the powerbank or power charger supplying it.

We also suggest to not attach the cable to the powerbank when it is not in use, especially in storage. It can still be feeding a small amount of current that can slowly discharge the powerbank.


Abe is the founder and Editor-in-Chief of YugaTech. You Can follow him on Twitter @abeolandres.

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38 Responses

  1. Correction for #3.
    Powerbanks don’t use “AA”. They use the battery cells found on laptop battery packs namely “16850”.

    Thanks :)

    • v says:

      correct. The article should be re worded. An 18650 doesnt look like an AA battery, an 18650 has the similar cylindrical shape as an AA battery, but is larger

      the 14500 li-ion battery is the same size and shape as an AA battery. But of course the voltage is higher. There are devices like LED flashlights that are designed to use either AA or 14500 batteries but if you use AA, the light is dimmer. If the flashlight is not designed to take the higher voltage then you will destroy it

    • lvn says:

      He didn’t say it’s AA… he said “Most powerbanks use a 65mm AA-like re-chargeable batteries… don’t miss the word “like”… AA-like

    • v says:

      true he said AA-like but the fact that you are one of the few people to spot it means its hard to find, or at least that people can easily miss it. Thats why you should include a large margin of error to avoid this

    • akoatkami says:

      hindi naman na siguro kasalanan ng nagsulat nito kung “few people” lang ang nakagets agad nung word na “like”.. ang mahalaga wala namang mali sa sinabi nya.. eh sa AA gusto ikumpara ng writer eh.. at totoo namang magkamukha yung dalawang battery mas malaki nga lang ng konti yung 18650.. kung gusto mo ng masasatisfied ka sa article.. gumawa ka nalang ng sarili mong website at dun ka magreview ng mga gusto mong ireview.. hindi yung pupunahin na mo na parang mali yung sinasabi ng yugetech.. hahaha..

  2. Dale says:

    I don’t number 3 is correct. Powerbanks use 18650 batteries, which are different from double A batteries.

  3. #3 is kind of weird.
    actually most powerbanks use 18650 Batteries.
    18650 batteries have capacities ranging from 1800mAh to 2600mAh. fake ones can go up to 4500mAh but have less than 100 charge cycles.
    most powerbanks use LG or Samsung 18650 NCR batteries that have around 2000 to 2400 mAh each.

    AA batteries are not ‘usually’ used for powerbanks because AA batteries usually have 1000-1500mAh but are 1.5volts only. powerbanks usually output 3.7v up to 5v, 18650 batteries output about 3.6v to 4.2v, so they’re the standard in powerbanks. sometimes 18500 or 18350’s are used for smaller models.

    if you series some AA batteries, it will make it harder for the regulator, also production will be costlier.
    if you do paralle with 18650’s, it will be a 3.7v standard, and the manufacturers will just use wirings and simple chips, making production cheaper.

  4. Yack says:

    Hi Abe. Can you suggest where to get those 28/24 gauge cables? Online advertisements does not give out those specifications.

  5. infoseeker says:

    # 3

    3) Double A Batteries (cylindrical lithium-ion rechargeable). Most powerbanks use a 65mm AA-like re-chargeable batteries (18650, cylindrical lithium-ion rechargeable)
    >>>> Double A batts size into Lion ay yung mga 14500Lion na model na mas maliit compare sa 18650.
    18650 are too big compare sa AA

  6. mark says:

    Sir Abe, please note that batteries are not connected in series. Parallel connection is used to increase the overall capacity. Connecting batteries in series results in increased voltage, not overall charge capacity.

  7. patrick says:

    “mAh” is a unit of energy not charge. This is similar to the kilowatt-hour energy consumption you find in your Meralco bills. The difference is the magnitude, which is described in milli(0.001) instead of kilo(1000).

    • dobits says:

      You may want to recheck. mAh and kWh are totally different, in both magnitude and unit. Even if you scale them to a common magnitude scale, they are pointing to different electrical properties. Ampere*Hour = (Q/t)*t = Q
      while, Watt*Hour = V*A*t = V*(Q/t)*t = QV

  8. patrick says:

    My bad. Please ignore previous comment.

  9. TacticalNinja says:

    Tsk tsk. Not sure if you did your homework, or if you just used your “stock knowledge” to write this article, OR you did your homework, but did not understand it fully. First of all, USB is standard. Powerbanks have USB’s. Therefore powerbanks only output the standard 5 volts that is used by ALL USB’s (USB 1 to 3 all use 5 volts, the difference is the Amps produced.) The 3.7 volts, on the otherhand, is the voltage of the powerbank’s BATTERY. It passes a DC-DC up converter of 3.7 to 5 volts. There’s no such thing as a 3.7 volt powerbank (If there is one, it’s not using USB standards!)

    I’m not sure where you got that formula. But it looks like the formula to get WATT, not watt-hour.

    WATTS is computed by W (watts) = I(amps) * V (volts).

    WATT-hour is computed by Wh (watt hour) = mAh (milliamp-hour) * V (volts) / 1000. *You can remove the divide by 1000 if you are using just Ah (not mAh) to compute for the Wh.

    • I think that’s why there was a “The typical voltage for Li-Ion in powerbanks is 3.7V but output can go up to 5V. This is the reason why we see either of the two numbers in smartphones, laptops, or powerbanks.”

      ‘can go up to 5v’

      anyways, powerbanks have 3.7v 18650 batteries, what makes them give out 5v via the USB is the voltage controller chip.
      like Xiaomi’s Mi Powerbanks (the original ones), they use those good ones from Texas Instruments.

      the fake ones and other generics use simple anywhere-in-china-you-can-find ones.

    • TacticalNinja says:

      I’m well aware of that line, and that line is what tipped me off. Saying “up to” means it can provide something lower than that, and the fact that ISP’s use that term is that they can’t provide speeds of what the actual numbers are. So if you are saying “up to 5 volts” you may be looking at a non standard USB. Because USB should ALWAYS produce 5 volts to the point that it should not be mentioned anymore because it is standard.

  10. bully123 says:

    pagenius attack, lol

  11. Kul says:

    May makakapag-suggest ba kung saan nakakabili ng mga 2A na cables? Kasi ang hirap maghanap and mga wala pang nakasulat usually

    • Nucleus says:

      #5 is overkill, for #28 sobra sobra na ang 1 amp(kalahati ng #24 ang #28) para sa mga gadgets tulad ng smartphone/tablets na typical na gumagamit lang ng 10-50mA na charging current sa lithium battery

  12. me says:

    I bought my cable at Octagon store. They have pretty nice and affordable cables there.

    It’s brand is Silvertec. 2A cable with aluminum case copper high speed.

  13. v says:

    The input is usually 1A or less. The output USB is usually either 1A or 2.1A

    higher Amp rating means if the device is designed to accept 2.1A and is plugged into the 2.1A usb port, it will charge faster. A device designed to accept either 2.1A or 1A will of course charge slower if plugged into a 1A usb port

    Interestingly, some power banks have a higher amp rating for their input port. This means that if you attach the appropriate higher amp charger, the powerbank will charge faster

  14. Easy E says:

    Daming natutunan ng author dito. Nakalimutan na ang basic circuits. CpE yata si Abe?

  15. Hen-Sheen says:

    I never charge my Powerbank until it reaches 10% below or, it runs out power completely! Discharge Efficiency on Powerbanks could have two factors (In My Opinion):

    1. Shipping N’ Handling

    2. The Quality of those batteries inside the Powerbank

    At least the Gameboy External Battery charger (1st release) never have these issues of today’s “User Friendly” batteries…..

  16. Marcus says:

    Aside from Anker Powerbanks that is known for premium quality powerbanks. Kinkoo Powerbanks are also regarded as premium powerbanks. you may check there website for more info: http://www.ikinkoo.com/

  17. techshop28 says:

    authorized Dealer of Anker Available at http://www.techshop28.com

    contact # 09174683333 (02)3576962

  18. kodigo says:

    Ayos yung ganitong mga review. Madaming students ang may mapupulot na aral, tsaka review narin sa nakakalimot. Salamat sa mga nag comment na henyo at na update si article writer. To article writer, lagyan nyo po ng timestamp sa ibaba ng headline para clear kung updated na yung info para ma kumpara sa comments timestamp. More post that leads to info like this,in the long run magiging source of assignment answers na yugatech. :D

  19. Manny says:

    Is this a paid ad article by Anker?

  20. denise says:

    just a quick question: would you still be able to use the rechargeable batteries even without the circuitry in the powerbank? if so, how would I do that? I have a 20k-powerbank which didn’t even last six months so i really doubt that the batteries are the ones which ran out of power.

    • v says:

      18650 sa loob? you could buy a powerbank na walang batts, yung tipong empty and you provide the batts. But make sure compatible sa 18650 mo. Most powerbanks have unprotected 18650’s so make sure pwede unprotected 18650 sa powerbank na yun. protected 18650 is slightly longer than unprotected

      sa 18650 flashlights I dont know if pwede ang unprotected. Not sure but most 3xAAA flashlights might be able to use 18650’s

    • denise says:

      yes, 7pcs na 18650. what do you mean unprotected? and any suggestion kung saan pwedeng makabili ng powerbank na walang batteries?

  21. boy tofu says:


  22. arvi says:

    Any reputable author would think twice before making a technical statement that isn’t completely true or even WRONG! Study basic electronics before making a technical discussion about consumer electronics’ specs.

    Clarification on # 2:
    Power Storage Capacity
    “Powerbanks cannot store 100% of the full power capacity that it states it can.” This is not the reason why we cannot get the full capacity as the powerbank tells us. geez.

    Powerbanks in essence should charge their batteries at full capacity or very near under normal circumstances. Let’s say a 10,400mAh can actually contain 10,400mAh capacity. So next question is, is it true that we cannot harvest all 10,400mAh worth of charge? YES we cannot. While the idea of the #2 is real, it doesnt mean because the battery cannot be charged completely. IT IS BECAUSE THERE IS CONVERSION LOSS DURING USAGE. NOT because the battery aren’t actually fully charged. Dont buy from a powerbank manuf if they claim it cannot charge the battery at full capapcity. I believe the author is very mis-informed or didnt read more about powerbanks and voltage converters/regulators.

    Here is the most relevant explanation in consumer lingo as possible:

    While mAh capacities can be computed from the specs of the batteries inside the powerbanks. We cannot fully harvest every mAh of it because of the conversion losses that includes resistance, heat losses and other factors. So what conversion loss is? Definitely it is not what the author explained. i have a 10,500mAh and 15,600mAh powerbanks and i only get at least 8000mAh and 12,500mAh from both of them per my estimate. So where goes the remaining advertised capacity? The circuits inside consume energy too. Where do you think they get the power to get the circuits running to maintain clean and regulated 5v to your phones and tablets? Of course circuits must consume power or energy from the battery in order for them to work.

    The powerbanks contains 5v regulators and Voltage converters. These circuits consume generous energy in order to do its job. Regulators needs higher input voltage and some current to operate thus consuming energy. Voltage converters is also a power hungry circuit since it does more than regulators. Imagine how a single 3.6v battery powerbank deliver a 5v charging voltage to your iphone? It needs a series of step up circuits with capacitors and/or AC generators to convert 3.6v to 5v and you just cant use transformer alone since it is first in DC.

    Our world is not a perfect world and thus the circuits and powerbanks we use. Battery age too so it cannot charge full capacity in 2 years on daily use. But still, the author’s context is still wrong. Being not perfect is not an excuse in this one. Editor’s job must be used to an extent.

  23. CocoLoko says:

    It should also have a safety cuT-off feature. We all know that charging high capacity powerbanks really takes a lot of time. That is why, some of us charge it overnight. If the powerbank have this feature then LESS WORRIES.

  24. anna says:

    ganda ng environment dito, open to all, all comments and suggestions andito. sa techpinas dinelete post ko and na block ako kasi i was hitting the author for copying an article from another website.

  25. Iwillteachyoubasics says:

    The battery is not connected in series!
    it is in parallel! OMG study before posting!

  26. Random says:

    why so rude ppl

  27. Darwin Del Rosario says:

    Nice info! :)

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