As often happens in our imperfect world, common units of measurement capacity batteries steel units are not able to accurately reflect capacity. This ampere-hours and milliamp-hours.
Batteries and battery assemblies are at different rated voltages. In this battery 7.4 V 2000 mAh has twice the capacity than 3.7 V 2000 mAh. Capacity is different, and the numbers millimper-chaso same. Because of this, there is the eternal confusion.
The correct battery power measurement unit - watt-hours (Wh). They will not be any confusion: the first battery has a capacity of 14.8 Wh, the second 7.4 Wh. In this case, to get the watt-hours I just multiplied the nominal voltage of the battery on charge in ampere-hours (1Ah = 1000mAh).
More confusion arises when milliamp-hour capacity pauerbankov point. An ordinary pauerbanka output of 5 volts, and milliamer clock believe, based on the voltage 3.7 volts (typically a voltage in the internal battery). If you measure how much milliamer hours gave an "honest" pauerbank 10000 mAh turn something around 6600 mAh, taking into account the efficiency (10,000 * 3.7 / 5 * 0.9).
When specifying the capacity in watt-hours (Wh for 37 pauerbanka 10000 mAh) everything is much simpler and clearer.
There is one more thing. The voltage at the lithium battery during the discharge falls from 4.2 to 3 volts, and a nominal voltage of 3.7 V only secondary importance.
The actual amount of energy which the battery will issue can be counted only in watt-hours by multiplying the current voltage to the current current at each time, and to give the final capacitance value of the sum of these values, dividing it by the number of counting in hour.
That is why all of the devices that measure the capacity of rechargeable batteries in milliamp-hours give only approximate results, since the voltage in the discharge process is changing, and this is not taken into account.
Accurate results can only be in watt-hours, provided that in the discharge process is a plurality of measurements.
© 2019 Alex Nadozhin
The main theme of my blog - Equipment for human life. I write reviews, share experiences, talk about all sorts of interesting things. My second project - lamptest.ru. I test LED lamps and help figure out which ones are good and which are not.