Watt Hours to mAh Conversion

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Watt Hours to mAh Conversion

mAh is a parameter used to measure the size of batteries, which is common in small-capacity electrical devices such as mobile phones, computers, tablets, etc. However, to understand the true capacity of a battery, it is better to use Watt Hours, or Wh, because mAh also takes into account factors such as battery voltage. This article attempts to introduce the calculation method of Watt hours to mAh.

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Before Detail, Conclusion First

Before introducing the details, I would like to list the relevant calculation formulas and conclusions first so that you, as a professional, can just find the direct relationship between them without detailed explanations:

Battery Capacity(In Ah) = Battery Capacity(In mAh)*1000

Battery Capacity(In Ah) = Current(A)*Time(hour)

The calculation formula for Battery Capacity in Ah to Wh is as follows:

Battery Capacity(In Watt-hour) = Battery Voltage(V)*Battery Capacity(In Ah) 

If you are not an expert in this area and want to understand their meaning in depth, please read the full text as follows:

A Practical Example

Battery Example

This is the lithium battery of my robot vacuum cleaner. In order to calculate Watt hours to mAh, we need to read the following important parameters:

Battery Voltage (sometimes written as rated voltage, nominal voltage). In the above picture, it can be read as 14.4V.

Then we need to read the Rated Capacity (sometimes written as battery capacity). In the above picture, it can be read as 5000mAh.

In fact, this battery has already told us that its capacity in Wh is 72Wh. We need to know how to calculate it.

The following formula ties Battery Capacity (In Watt-hour) and Battery Capacity (In Ah) together:

Battery Capacity(In Watt-hour) = Battery Voltage(V)*Battery Capacity(In Ah) 

 

First of all, please note that the unit of Battery (in Ah) here is different from the unit of mAh, and what we read on the battery is 5000mAh. So we first need to convert mAh to Ah:

Battery Capacity(In Ah) = Battery Capacity(In mAh)/10000

                                         = 5000mAh/1000

                                         = 5Ah

 

Then we put 5Ah into the formula:

Battery Capacity(In Watt-hour) = Battery Voltage(V)*Battery Capacity(In Ah) 

                                                     = 14.4V*5Ah

                                                     = 72Wh

So now we have figured out the relationship between battery Watt hours to mAh.

If we combine and simplify the formula, it becomes as follows:

Battery Capacity(In Watt-hour) = Battery Voltage(V)*(Battery Capacity(In mAh)/1000)

Extra Pratice for Watt hours to mAh

Let’s do an exercise: 200Wh of electricity is equivalent to how many mAh of battery? Assume that the battery voltage is 12V

Using our formula:

Battery Capacity(In Wh) = Battery Voltage(V)*(Battery Capacity(In mAh)/1000)

Battery Capacity(In mAh) = (Battery Capacity(In kWh)/Battery Voltage(V))*1000

Battery Capacity(In mAh) = 200Wh/12V*1000

                                            ≈ 16666.67mAh

So in this example, the result of the 200Wh to mAh conversion is 16666.67mAh.

Summary of Watt hours to mAh

The above is a detailed explanation of Watt hours to mAh. Please note that Wh is the real benchmark for measuring battery power. When comparing battery power with mAh or Ah, the premise is that the voltages of the two comparisons are the same. If one battery is compared with another battery, their voltages are different, and their power needs to be converted to Wh for comparison. If you want to know more about the definition of Ah and the definition of Wh, please refer to the following article:

Reference: Ah to Wh

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