how to discrimination lithium battery Capacity

The power consumption of electrical appliances is calculated in “degrees”, 1 degree = 1000Wh (watt-hours). However, the laptop battery has a small battery level, and it is obviously unreasonable to use “degrees” to measure it. Therefore, “Wh” (watt-hour, which is one thousandth of a degree) is commonly used internationally.

W = Pt, where W, P, t are the representative symbols of “energy”, “power”, and “time”, and their units are usually “Joule J” “Watt W” “second s”.


W = Pt = 1W * 1s = 1J, which means that a one-watt consumer consumes 1 joule of energy in one second

W = Pt = 1kW * 1h = 1kWh, which means that a one kilowatt consumer consumes one kilowatt of energy in one hour.

P = UI, where P, U, I are the representative symbols of “power”, “voltage”, and “current”, and their units are usually “W”, “V”, and “A”.


P = UI = 220V * 0.18A = 40W, which means that the power consumption of a bulb connected to 220V AC power is 40W

W = Pt = 40W * 1h = 0.04kWh, which means that this bulb consumes 0.04 kWh in one hour

If U is transposed to E (representing electromotive force, which is the ability of the battery to carry electricity, the unit is usually volts V), that is, W = Pt = EIt, we can know the capacity of the battery. The data marked on the battery is usually milliampere-hour mAh, which is a unit of current I * time h and represents the amount of charge. If a cell is marked as 2200mAh, it is 2.2Ah. Through W = UIt = 3.7V * 2.2Ah = 8.14Wh, we can know the capacity of the cell.

Look at the battery capacity of the laptop, not the mAh at the back, but the calculated Wh.

Large notebook computer manufacturers are clearly marking the battery capacity Wh on the battery pack according to the aviation law.

Generally, Sony battery cells are green-skinned and black-headed, and the battery capacity is between 2400mAh ~ 2600mAh. Sanyo battery’s red skin green head capacity is 2400mAh, and the red skin light blue head capacity is 2600mAh.

The 18650 battery cell is distinguished by the color of the cover. Japan’s Sanyo18650 has white and yellow heads of 1950mah; blue heads of 2000mah; red heads of 2200mah; light blue heads of 2600mah; purple heads of 2800mah; yellow heads (cut-off voltage of 4.35v) of 3000mAh; green heads of 2400mAh.



Post time: Nov-28-2019