When it comes to batteries, a power bank, the battery of an Apple iPhone or MacBook, DJI drones, cameras or other mobile devices and their power supply, the abbreviation mAh is often used. But what does it mean and what does it say? What conclusions can you draw from the mAh information and which values should you also have in mind? The answers to these and other questions are given below.
Chapter in this post:
The standard size: Ah
I will go into the mAh, i.e. the mAh, in the next paragraph. First of all, just briefly: The starting value for the unit is the ampere hour, which is a thousand times a milliamp hour. It indicates the amount of charge that flows through an electrical conductor in one hour (h) as long as the electrical current is 1A.
That means the abbreviation mAh: Milliamp hour
If you are charging yourself to a smartphone battery, the technical data of a laptop or if you want to buy powerful AA batteries, then you will surely get past the unit of measurement mAh. This denotes the physical quantity of the milliampere hour; so the thousandth of the ampere hour (Ah). Often the specification (also admittedly here in the blog) is referred to as the “capacity” of the electricity storage system, which is not entirely correct, but has become commonplace in everyday language.
The ampere hour Ah or milliampere hour mAh usually only indicates a nominal charge or a "charge carrier capacity", which differs from the power capacity (specified in watts). It is practically applicable Amperevalue, however, to specify a runtime of the rechargeable battery or the battery with a constant discharge current. The equation for determining battery life is therefore: t=Q/I – where t is time (h); Q for charge (Ah); I for discharge current (A).
Example: Power bank with 20.000 mAh
Let's take that as an example AUKEY PB-N15 power bank with 20.000 mAh or the equivalent of 20 Ah. Their discharge can be realized with a maximum of 2,1 amps, which means that we can apply the above equation for the running time as follows: t = 20Ah / 2,1A. This means that the runtime of the power bank at the maximum discharge current is 9,52 hours. However, you should bear in mind that many, especially older devices, sometimes only discharge with one, one and a half or two amps.
A closer look with energy storage capacity Wh or kWh
As already mentioned above, ampere-hour and milliampere-hour only indicate a nominal charge or “charge carrier capacity”. It has little to do with the electrical capacity, which is given in Farads, or with the power capacity in watts. More meaningful for the energy storage capacity and thus with the actual boom in the battery are the values Wh (watt hour) and kWh (kilowatt hour). However, with the information in mAh, you can calculate those quantities if you know the output voltage in volts.
With the power bank mentioned above, the output voltage is, for example, 5V. If you compare this 5V with the 20Ah of the mobile electricity supplier, you get a value of 100Wh using the equation W = Q * U. Incidentally, this is also the limit value for power banks and similar batteries / accumulators that you use in the aircraft hand luggage can pack.
Conclusion on mAh
The abbreviation mAh stands for milliampere hour and indicates the nominal charge of the accumulator, battery and Co. However, this means that the actual capacity is not specified, but only a guide value for the runtime of a battery with full memory. The actual battery capacity of smartphone, tablet, camera, power bank and so on is only calculated by multiplying it by the output voltage. If you convert the data from the power bank and the smartphone equally, then you can specify more precisely how often you can charge the smart phone with the mobile power storage.
After graduating from high school, Johannes completed an apprenticeship as a business assistant specializing in foreign languages. But then he decided to research and write, which resulted in his independence. For several years he has been working for Sir Apfelot, among others. His articles include product introductions, news, manuals, video games, consoles, and more. He follows Apple keynotes live via stream.