# Know the Difference Between Real & Rated Power Bank Battery Capacity

Needless to say, power banks have made the mobile charging process easier as it doesn’t need to stick with the power plug. It extends the battery life of tablets, smartphones and mobile phones. We have all experienced a common scenario once in a lifetime while charging a mobile phone. Here it is. The power bank hasn’t worked efficiently as it should be. For example, a fully charged 5000 mAh battery couldn’t charge a 3000 mAh phone battery sometimes. That makes users disappointed.

There is a huge difference between rated & real power bank capacity. Let’s know.

Misleading Promotion on Capacity:

Do you know what is the biggest misconception about the power bank is it can deliver the same charging capacity as it listed in the specifications? For example, a 10,000 mAh battery can charge a 3000mAh battery at least 3 times. However, users ignore the factor: Power losses.

In Reality, the power bank doesn’t deliver the same result as mentioned in technical specifications. Manufacturers mention the full capacity instead of actual capacity and this is only for boosting sales. But not all manufacturers do the same thing; some giant brands power banks deliver similar results as promised.

Then How Do Power Losses Happen?

In general words, a power bank is made of multiple batteries, circuits and other electronic equipment to manage power flow. A lithium power bank store electric energy rated at 3.7 V and the genuine USB output is 5V. To manage the Voltage difference, a converter is needed and that causes power loss.

Even a USB cable causes power loss due to joule heating. This happens because of internal issues. In short, the actual power bank capacity is 10-25% lesser than the rated capacity. The efficiency may vary from one to another. So, check for the efficiency, not the rated capacity when you buy power bank online.

How to Calculate Real Power Capacity?

Generally, most people consider the 2/3 of the written capacity on a power bank as an actual capacity. However, it’s not true all the time. Here is a simple formula that can help you calculate the real power capacity.

Real Capacity = Advertising battery capacity X 3.7 V (voltage) X efficiency in decimal / 5 V

For example, let’s take a power bank of 5000 mAh battery capacity with an efficiency rating of 91%; the actual power bank capacity as per the formula would be:

Actual capacity = 5000 mAh X 0.91 X 3.7 V / 5 V = 3367 mAh

The result is quite similar to the 2/3 of advertising capacity. The final result indicates that only 67.34% of the mentioned capacity can be delivered to your mobile phone.

I hope you have got the real reason behind not getting the performance you want when purchasing a power bank. Consider the real power bank capacity not rated. Type C Power Bank is in trend right now because of its highest efficiency.