10.8V / 11.1V vs 14.4V / 14.8V output voltage

Why laptop battery have 10.8V, 11.1V, 14.4V, 14.8V rating, how they calculated?

Each laptop battery contains a certain cells, i.e. 4 cells, 6 cells, 8 cells, 9 cells or 12 cells.

Each cell has 3.6V or 3.7V, there is no difference between 3.6V and 3.7V, and each cell has 1800mah / 2200mah / 2400mah / 2600mah / 2800mah or 2900mah capacity.

Let’s say laptop battery manufacturer using 3.6V 2200mah cells to make laptop battery: the working principle is when cells are linked in series, the current is no change but total voltage is sum of all cells voltage; when cells are linked in parallel, the current is sum of cells but the total voltage is no change.

1)      For a 4 cell battery, 4 cells is set in series, the mah is same 2200mah across cells but total voltage 3.6V x 4 cells = 14.4V, so, this battery is rating 14.4V 2200mah, if calculated by 3.7V each cell, the battery rating is 14.8V 2200mah, there is no difference between 14.4V and 14.8V battery, they are interchangeable.

2)      For a 6 cell battery, each 3 cells linked in series a set, 2 set of 3 cell is linked in parallel. So, each set of 3 cell has 3.6V x 3 cell = 10.8V 2200mah, 2 set of it in parallel is 10.8V 4400mah. If calculated by 3.7V 2200mah each cell, the battery output rating is 11.1V 4400amh.

The same method of calculation for 8 cell, 9 cell and 12 cell batteries.

10.8V is same with 11.1V, if original battery rating is 10.8V, you can replace it with either 10.8V or 11.1V battery, but you cannot replace it with 14.8V;

14.8V is same with 14.4V, if original battery rating is 14.4V, you can replace it with either 14.4V or 14.8V, but you cannot replace it with 10.8V.

Indicates how much Full Charge Capacity has become less compared with Designed Capacity. A battery wears gradually as it goes through charge and discharge cycles and its capacity decreases. You may find the function of Battery recalibrating in the BIOS which could improves the battery wear level.