# How to calculate the number of cells in a Li-ion cordless power tool battery

In my last article, we know how to calculate cells in Li-ion laptop battery, and what a 18650 battery cell is. And, let learn How to calculate the number of cells in a Li-ion cordless power tool battery.

It is known that the Li-ion Cordless tool battery is also made by 18650 battery cell. So, it is very easy to calculate the number of cells in a Li-ion power tools.

For example, the Makita BL1830 Battery, it is a 18 V, 3000mAh battery. How many cells in it? Let’s calculate it.

To make the voltage to 18 V, it needs 5 series of 3.6 V cell, and to make capacity to 3000mAh, it needs 2 parallels of 1500mAh cell. So, the total of a 3000mAh Makita BL1830 battery is 5*2 = 10 cells.

But, some people may say, why not use a 3.6 V 3000mAh battery cell to build it? The reason is, power tools is heavy duty machine, it need much more power than the nomal laptop battery, so the density of the chemistry material is much more than laptop battery cell. It is hard to do it.

For Li-ion cordless tool batteries or notebook batteries, normally speaking, the higher capacity (mAh), the larger in size, and heavier in weight. Of course, more capacity means longer run time. A 1500mAh 18 V battery will run longer than the 3000mAh 18 V battery, but may not the running time.