How To Choose Suitable Portable Power Bank For Your Android, iPhone or any Smartphone?

Power banks or Portable Batteries or Battery Packs, whatever you call them but all serve one purpose! To give you power on the go without a need to look for power output. Just like cables, Power banks come in different shape, size, capacity, and don’t get me started on the features. Some do just light up as well! I have seen some powerbanks that can jumpstart a full size SUV!! How cool is that? Here, I’ll give few tips to choose best powerbank for your mobile phone suitable for your needs.

choose right suitable portable best power bank for your iphone android mobile phone
So with all these option, how to buy right powerbank one that gets the job done for you?

What is Power Bank Capacity, mAh?

Let’s start by understanding what exactly is the capacity of a Powerbank? How it is measured? How much of the stated capacity you actually get? Is there any difference between genuine branded powerbank and a cheap powerbank (you guessed it right from some shady seller outside your local railways station)? Well let’s find out the answers.
Now first what is the powerbank capacity? The amount of charge the battery cells inside the powerbank can hold. It is generally measured in mAH (milliAmp-Hour) or WHr (Watt-Hour). Now we know that we never get even close to what mentioned capacity on the powerbank. So, how to know what you are going to get?

Inside Powerbank
if you open a powerbank something like this is expected to be seen. (If not, you might be screwed)

If your phone has 4000 mAh battery and if you buy powerbank of 2000 mAh capacity, its not going to last enough! So, make sure you look at your phone’s battery capacity too while choosing right powerbank for your mobile phone. There is a theoretical equation to calculate the USB output capacity from a powerbank. Let’s understand some basics. Inside powerbanks are 3.7V batteries (this voltage varies but only in point margin) but the USB standard is 5V. Between the battery and the USB socket is a conversion circuit and this changes the 3.7 V into USB friendly 5V. When converting into a higher voltage you must also convert the mAH into the new voltage.

How to Calculate Power Bank Capacity? (Formula)

A simple equation can be used to convert the 3.7V into 5V.
Capacity with respect to 5V = 3.7 X Advertised Capacity / 5
In this case a 10,000 mAH powerbank: 3.7 X 10,000 / 5 = 7,400 mAH
So a 10,000 mAH at 3.7V powerbank really only supplies 7,400 mAH at the 5V USB connection. So straight out of the box is a 26% reduction in the stated mAH. But that’s not it, there is also something called as conversion loss. What is a conversion loss?
As you use your powerbank, the circuit inside that converts 3.7V to 5V USB uses some energy and also creates heat. During this conversion you lose some charge. This loss is called as conversion loss. There is a wide range in conversion efficiency and most brands don’t state the losses, but here Xiaomi has prized themselves on their conversion efficiency chips which are up to 93% efficient, meaning you only lose 7% off your battery power in the conversion. This loss is more is the cheap generic powerbanks as conversion circuits are not even remotely as sophisticated as the ones of branded powerbanks.

You can see 5V output, which is a standard for USB output

So now what you actually get out of your powerbank?
To get a rough idea the equation (yeah! I know maths suck. But it is part of life. Deal with it) will be
Actual output percentage= (Capacity with respect to 5V / Advertised Capacity *100) – conversion loss
In this case, Actual output= (7400/10000*100) – 7%
= 67%
So the mi powerbank should supply roughly 67 mAH of charge. Which is good enough to charge most smartphones at least 1.5 times if not more. But again this percentage varies on the basis of conversion loss.

Most major manufactures mentions the efficiency along with minimum charge

Now a bonus answer. Why don’t they just state the actual output?
The manufactures don’t need to!! As technically, most people have no idea what’s inside the box. By not giving the actual 5V output brands can reap these benefits;
• Manufactures can have a higher number of mAH for their powerbank and sound more powerful.
• It avoids the talk or testing of conversion loss and brands with low efficiency conversion chips can still market them in the same league as other efficient brands.
Some manufacturers will state in the manual or in small print on the device (but most will not state) the minimum output of the powerbank. So as a general rule always buy a powerbank with atleast 30% more charge capacity than you need.

Till now, hope you’ve learned how to choose right power bank for your phone! Make sure you share this post with your friends too.


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