You can’t have enough battery..

Smartphones have become our daily life companion and we need more and more battery life. Mostly a full charge is not enough for a day of use if you are heavy user. The easiest way to extend your battery life is a powerbank, because it allows you to still use your smartphone on the go while charging. The variety of powerbanks is huge, you can find so many powerbanks on amazon or aliexpress and they just differ in size and form. So which one should you buy? If you checkout powerbanks on amazon, then you can find alot of mixed reviews. Many reviews are paid and some reviews just come from people who have no idea what they are talking about.

Which one should you buy ?

So most people just search for the biggest capacity advertised for a low price. But this is something you should not do and the reason is that sellers  mostly lie about the capacity. Not only the battery capacity is mostly wrong advertised, there are even fake powerbanks from china which have fake cells inside or are filled with sand. If the product is too cheap to be true, better keep your hands off, otherwise you will maybe get a counterfeit product with fake cells. First let me explain how a powerbank works and why you can’t simply divide your powerbank capacity by your phones battery capacity. There are different kind of powerbanks with different battery technologies inside. Cheap powerbanks use Lithium-ion cells, especially the affordable 18650 cells. They are cheaper and have fixed sizes. Lithium-ion batteries are common in home electronics. They are one of the most popular types of rechargeable batteries for portable electronics, with a high energy density, tiny memory effect and low self-discharge. Beyond consumer electronics, LIBs are also growing in popularity for military, battery electric vehicle and aerospace applicationsBut well thats the only advantage. They have a higher discharge rate, get hotter and are not really durable compared to the new Lithium polymer cells.


However LiPo powerbanks are more expensive and are harder to get but also smaller and more durable on the long run. LiPo batteries have the huge advantage that you can make different forms and you don’t need to use the cylindrical cells. That means you can create compact and fancy forms with them. Li-polymer offers slightly higher specific energy and can be made thinner than conventional Li-ion, but the manufacturing cost is higher by 10–30 percent. There is such a thing as a real lithium-polymer battery, which uses a polymer as the electrolyte in the battery instead of other standard liquid electrolytes.Thus also the lithium-ion battery’s can catch fire more easily because of their fluid electrolyte. Real Lipo batteries instead use a solid or gel electrolyte and are more safe. Well I know it’s not very realistic that your powerbank will catch fire, but safe is safe, here is a quick video i recorded 2 years ago. Imagine your powerbanks gets shorted and blows up like a note 7, not really funny.

Now lets talk about the actual capacity, because here it get’s tricky. Powerbanks get to 99% produced in china, most cheap unknown manufacturers or OEM’s just lie about the battery capacity. Thats a fact. But also the capacity advertised is not the actual capacity that goes into your phones battery. First the capacity inside is expressed as mAh – That stands for milliamphours and tells you how many milliamps or amps you can drain from the battery in one hour.

For instance a 10.000mah battery means you could drain 10.000ma or 10A from the battery for one hour. But you can only do this at the rated voltage of the cells and most cells are rated at 3,7V. If you multiply the mAh and the voltage you get the actual energy which would be 37Wh (10Ah * 3,7V) and that means you can drain 37W for 1 hour from the battery.

Why do we need to know all that ?

So you need to know that usb ports are made to operate at 5V. So you always plug your smartphone into a 5V source, this is the output of a phone charger or your notebook’s USB port. So inside of the powerbank the voltage has to be stepped up from 3,7V to 5V using a boost converter (Voltage transformer). This conversion is not lossless, that means there is a conversion loss and energy is being transformed into heat, which is lost energy. To calculate the real capacity, take the advertised powerbank capacity times 3,7/5. this is now your real capacity and its always lower than the advertised / rated capacity. Here in our example, the advertised 10.000mAh powerbank can only deliver 7400mAh @5V from the USB port.

How often can I charge my smartphone ?

Now this depends not only on the rated capacity of your powerbank. As explained before, the most importanf factor is the efficiency factor and this one depends on your powerbank. Cheap powerbanks have a bad converter inside that transforms alot of energy into heat, which is lost, high quality powerbanks have a better up-stepper resulting in a small loss. Good powerbanks lose here 15% some even 20% or more. Now lets do the math. Your 10.000mAH powerbank at 3,7V actually can only supply 7400mah @ 5V or maybe even less, and maybe in a couple of months even less because your cells alter. So if you thought you could charge your 2000mAH smartphone 5 times, you are now disappointed because you just have around 7400mAH coming from your powerbanks USB port and there is another conversion in your smartphone back to 3,7V.  Also powerbanks can’t be drained to 0%, there is always a rest capacity in your powerbank of lets say 10%

So this advertised 10.000mAH powerbank will charge your smartphone only around 3 – 3.5 times.

Which powerbanks are good ?

Let’s quickly summarize:

  • Buy a powerbank with high quality cells (Panasonic, LG…)
  • Check if it supports Quick charging for your smartphone
  • Check if the powerbank itself supports quickcharging (You don’t want a powerbank that takes forever to charge)
  • Don’t buy the cheapest ones (Fake cells, bad converters..)

Personally I can recommend 2 powerbanks which  I use very often:

MGCool Powerbank with 16.000mah:

Compared to other battery banks I have, this one offers a slight twist on what i’m used to seeing, being that this bank features USB-C Quick Charge 3.0 Fast Charging INPUT, as well as output. Also the high capacity and the real LG cells make this powerbank a bargain.

Purchase on Amazon US: Purchase on Geekbuying:

TIZI Flachmann for iPhone users:

Boxy, clumpy batteries are a thing of the past. Move on to the next level of external, mobile batteries. With the tizi Flachmann ULTRA, you’ll never need to hide your iPhone away while you recharge. Charge it and flaunt it!  Depending on your iPhone, you can charge it up to 1.5 times. It’s a really good powerbank if you only need a bit more battery life to make it trough the day and are looking for a small formfactor solution.


Check out Tizi on Amazon:

Checkout our video about powerbanks: N.p., n.d. Web. 26 Jul. 2019.