Mystery of power bank

When selecting the power bank , Several factors that are often considered ： Capacity 、 Quick charge 、 Whether you can get on the plane 、 Interface support , And some indicators are still hidden .

1. Capacity

The principle of the power bank is , Pre charge the built-in battery when external power supply can be found , That is, input electric energy , And stored in advance in the form of chemical energy , When required , That is, the battery provides energy and generates electric energy , With a voltage converter ( Direct - DC converter ) Reach the required voltage , By output terminal ( It's usually USB Interface ) The output supplies power to the required equipment for charging or other purposes .

The manufacturer publicizes the power bank , Often used is xxxxx(mAh), As shown below ,20,000mAh、30,000mAh, But in " Small characters " Column will have this explanation ,20,000mAh The rated capacity of is 12,000mAh( loss 40%),30,000mAh The rated capacity of is 18,000mAh( loss 40%),

In the specification , The data of these two capacities will be given ,

This is to understand " Battery capacity " and " Rated capacity " What's the difference? ？

Battery capacity Is the battery capacity of the power bank , The unit is ampere hour (Ah) Or Mah (mAh), Or the battery capacity of the power bank , It refers to the design capacity of the battery cell of the power bank . But when the battery is fully charged , Output the power to the receiving equipment , Due to conversion rate and self power consumption, etc , The power of the power bank will be consumed to a certain extent during the output process ( The main reason is that the battery capacity of the power bank is transformed into that of the mobile phone , To pass through the charging bank booster circuit 、 Internal resistance of mobile phone charging line 、 The two ends of the charging line are connected to the contact resistance of the socket 、 The power management circuit of the mobile phone itself 、 The internal resistance of the cell and other losses , This consumption is generally in 20%~40%), The capacity consumed by removing these is called Rated capacity , So battery capacity ( Cell capacity ) The value is generally larger than the rated capacity , In the two pictures above , According to the consumption 40% Rated capacity given .

Therefore, the actual power of the power bank we can use refers to the rated capacity , Of course, it is proportional to the battery capacity , It's just like a storage device , Not marked 1G Of U disc , Free space is 1G, This still needs to be understood .

2.  Whether you can get on the plane

Previous post 《 How much capacity power bank can you take on a civil airliner 》 Said this question . The official website of Civil Aviation Administration of China gives 《 Catalogue of articles prohibited to carry and consign by civil aviation passengers 》 and 《 Catalogue of articles restricted to carry on or consigned by civil aviation passengers 》,

The capacity of the power bank is described in both documents , As shown below ,

Catalogue of articles prohibited to carry and consign by civil aviation passengers .pdf

Catalogue of articles restricted to carry on or consigned by civil aviation passengers .pdf

It means ,

(1) The rated energy exceeds 160Wh The power bank of is forbidden to use , It's impossible to consign .

(2)  The rated energy is less than or equal to 100Wh The power bank of , No consignment , Only carry it with you .

(3) The rated capacity is greater than 100Wh、 Less than or equal to 160Wh The power bank of , It shall be approved by the aviation secretary , And only two pieces are allowed .

The units used here Wh, Instead of the power bank above mAh？ Actually Wh( Watt hour ),mAh( mah ),W( watts ) These are units of power ,mA Is the unit of current , power = voltage x electric current , namely Wh = voltage x Ah.

The voltage of the battery is generally 3.7V, therefore Wh = 3.7V x Ah, That is, a capacity of 10,000mAh The power bank of , The capacity is converted to Wh Namely ：3.7V x 10Ah = 37Wh, therefore 20,000mAh The capacity of the power bank is converted to Wh Less than the transportation limit of Civil Aviation Administration , and 30,000mAh You have to follow the third option above .

in addition , If the power bank handles the boost circuit , Output voltage , It is possible to achieve 5V, According to this calculation ,1 Wh = 5.0V x Ah, One capacity is 10,000mAh The power bank of , The capacity is converted to Wh Namely 5.0V x 10Ah = 50Wh.

If according to 5V Calculate the voltage ,160Wh The milliampere of the power bank is 32,000mAh.

If a careful friend , You may see that the Civil Aviation Administration gave you the following information " Rated capacity " Calculated , For the above calculation , All are " Battery capacity " Calculated , Both are calculated according to the maximum value , Should be " Battery capacity "x60% What you get is " Rated capacity ". If this is the case , Even if it's 5V voltage ,30,000mAh Charging treasure , His rated capacity = 5V x 30mAh x 60%, You can take it with you . And sometimes the airport security check looks at your power bank , Will find the marked rated capacity , It should have the same meaning .

But after all, the larger the battery capacity , There will be certain risks , In strict terms ,20,000mAh Power bank within , There must be no problem .

therefore , Small power bank , It still contains a lot of knowledge .

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