how to test the capacity of power bank with RD USB tester

Hello, everyone, nice to see you:

Nowadays when we are traveling or on a business trip, we will take a power bank because we don’t have so many chances to charge our mobile phones on the outlet, and I know there are some people who will fall into panic when their phones are out of power, because that is who I am. A good power bank can charge a phone several times and that enough for a day.

However, not all of the power banks have good quality, do you notice that power banks with the same milliampere hour can vary quite a lot in terms of performance, for example: one power bank says its capacity is 30,000 mAh, and I have a iPhone with 2,900 mAh, so it can power up my phone 10 times theoretically, but actually, the power bank is out of power after 3 times. So that I can make sure the capacity does not match technical parameters.

Today I want to show you some methods to measure the capacity of a power bank. 

1.Simplest way: 

You can just use your power bank to charge your phone, because you know the capacity of your phone battery, so that the capacity of power bank=phone battery capacity*charge times.

The consequence is not so accurate but it is not far from the real capacity.

2.Second way:

   You can just charge the power bank from 0% to 100%, the capacity=current*hours.

   In this way, you can know the rough capacity of the power bank but this way still has its shortage:

   ①the current is not constant, when the remaining battery is too low or too much, the current is lower than normal level.

   ②power bank has its effectiveness, so the input capacity is not equal to the output capacity.

3.Scientific way:

   Use a USB tester and a electric load to discharge the power bank from 100% to 0%, you can get the accurate consequence.

   We use our USB tester(UM25/UM34/AT35) to test the capacity, HD25/HD35/LD25 are used to discharge,set the current 2A

  set the data group at group 1, so that the capacity measurement can continue work next time we power it up

   here are the power banks:

Here is the consequence: 

Black power bank: 4223mAh (16000mAh) 

Brown power bank:5076mAh (10000mAh) 

Blue power bank: 6202mAh (6210mAh)

so only the blue power bank has good quality, and other two are trush,you can test it at home, go start,contact me if you meet any problem.

this article is not so detailed,welcome to add new things.