Wh: It is the same as the battery unit. What is the difference between it and mAh?

Careful children's shoes may notice that the battery for mobile power and laptop is also 5000mAh, but the latter is much larger than the former.

So the question is: they are all polymer lithium batteries, why are the same size difference between batteries? It turns out that although they are all lithium batteries, if you look closely, the voltage V and the electrical work Wh in front of the mAh of the two batteries are different.

What is the difference between mAh and Wh?

mAh means mAh, it is the unit of electricity; and Wh means watt hour, which belongs to the unit of electric energy.

The two are not a concept, and the conversion formula between them is: Wh=mAh×V(voltage)÷1000.

Specifically, mAh can be understood as the total number of electrons (the current is released at an intensity of 1000 mA, and after the release of one hour, the number of electrons flows through the number one). But if you want to know what the total energy is, you need to know how much energy each electron can calculate.

For example, we have 1000 mAh of electrons, each of which has a voltage of 2V, so we have 4 watts of energy. If each electron has only 1V, then we only have 1 watt hour of energy.

In general, mAh is like how much gasoline, such as 1 liter; and Wh refers to how far 1 liter of gasoline can run. To calculate how far a liter of oil can run, first of all, we must know what the displacement is, and the displacement here is like V (voltage).

Therefore, different types of devices (because of the different voltages) are generally not measurable by the size of the capacity. The battery of the notebook looks bulky and the power is larger, but the work done at the same time is far greater than the battery of the mobile power source, and the battery life is not necessarily better than the mobile power supply.

Why don't you use mAh as a restriction instead of "Wh"?

People who often fly by plane may know that the Civil Aviation Authority regulates lithium batteries as follows:

Portable electronic devices with lithium battery capacity not exceeding 100Wh must be carried with you when you are on board. They must not be stored in baggage. Passengers can carry all electronic devices with them. The total battery energy must not exceed 100Wh. Lithium batteries exceeding 100Wh but not exceeding 160Wh need to be checked by the airline for approval, and 160Wh lithium batteries are prohibited from being carried or checked.

We must not only ask, why does the aviation bureau not use mAh as a unit of measurement?

Originally, considering that the battery will explode, the strength of the explosion is directly related to the energy (Wh is the energy unit), so it is necessary to stipulate an "energy unit" to limit. For example, a 1000mAh battery, although the power is small, but if the battery voltage is as high as 200V, then the energy is 200 watt-hours.

Why does the phone use mAh to describe the battery instead of watt-hours?

The lithium-ion battery of the mobile phone is marked in two units, just because many people do not understand the concept of watt-hours. The other reason is that 90% of the lithium-ion battery of the mobile phone is a 3.7V polymer battery, and there is no series-parallel connection between the batteries. Combination, so directly speaking, the power will not cause much error.

The other 10% uses a 3.8V polymer. Although the voltage is different, it is only the difference between 3.7 and 3.8, and the error is not large. Therefore, it is ok to use mAh to describe the battery in mobile phone promotion.

What is the battery capacity of notebooks, digital cameras, etc?

These products have different battery voltages, so all of them clearly indicate the energy unit "Watt hours": low-end laptop battery is about 30-40 watt hours, middle end is 60 watt hours, high end is between 80-100 watt hours; digital camera Between 6-15 watt hours; mobile phones are generally 10 watt-hours.

In this way, if you want to fly, you can probably bring a notebook (60 watt hours), a mobile phone (10 watt hours) and a digital camera (30 watt hours), which is close to the upper limit.