Monday, August 19, 2019
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How to calculate Power Bank mah

Introduction
The capacity of a Power bank is the first element to consider when you are to buy a power bank. How to check real power bank capacity becomes a question since there is a large capacity range in current market of power bank. You can buy power bank 2600mAh, 10400mAh, 20000mAh or even more powerful power bank according to your needs.

Power Bank

What is a Power Bank
Powerbank is also known as battery charger. They are widely use by every person worldwide now with the rises of smartphones and tablet. Powerbank not only to charge smartphone and tablet power but also some other gadjets such as camera, PSP, and many more.

What Does mAh Stand for?
While these units come in all shapes and sizes, they also vary in power capacity, much like the variety of smartphones on the market.
The term you most often seen while researching these units is mAh. It’s an abbreviation for “milliampere hour,” and it’s a way to express the electrical capacity of smaller batteries. The A is capitalized because, under the International System of Units, “ampere” is always represented with a capital A. To put it simply, the mAh rating denotes capacity for power flow over time.
How to calculate your Power bank’s capacity
Basically you charge the powerbank (full discharged first) and get the Amp reading from the start and again at the end when is fully charge. Then note the full charge duration of the powerbank. Once you got the duration and the two Amp readings you can calculate the mAh.

What you need?

1. Powerbank
2. USB current voltage meter
3. USB power source such as USB AC adapter
4. Timer, clock or a stop watch
5. Continuous recording camera such as car dash camera. This is optional if you are lazy to keep checking full charge time.

Here are the steps:

Step 1: Fully discharge your powerbank.
Step 2: Plug the USB voltage current meter to the USB power source.
Step 3: Begin charging the empty powerbank and start timer. Immediately take note of the Amp reading. You can use a camera to record.
Step 4: Note the last Amp reading just before it is fully charge because there will be no current when the powerbank is full. If you use a camera, you can check the last Amp reading.
Step 5: Once you get Amp reading and charge duration time. Here is how you can calculate based on the Amp reading you get.
Let’s take a 2600mAh power bank as an example. As the most decent power banks are about 90% efficient, and then the actual capacity of the power bank is around:

Claimed power bank capacity (2600mAh) * battery efficiency (90%) = 2340mAh
take note of the amp in the beginning and wait for the power bank to be fully charged;
take note of the amp when the charging stops.
We can get 3 numbers from the experiment: amp in the beginning (0.7A), amp at the end (0.34A) and charging time (3h 53m 05s). So we can calculate that the capacity of the 2600mAh is:

Average amps (0.52A) * charging time (3.88h) = 2019mAh.

Conclusion
There you have it. You now know what a power bank is, what power (mAh) is stored in a power bank, and how to calculate how many recharges your power bank can supply to whatever device you decide to use.

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