Battery Devices - Volt, Ampere or Watt: What Matters?

In this article, we explain what the terms Volt, Ampere, and Watt really mean in combination with power tools. There are many different manufacturers of power tools and battery machines. Examples include manufacturers like Makita, Milwaukee, and Metabo.

The Number of Charge Cycles and Battery Life

A charge cycle is the repeated charging and discharging of a cell. If a battery is only partially charged, it is referred to as "partially charged." For example, a partial charge of 60% and 40% constitutes a full charge. If the manufacturer specifies a number of 800 charge cycles, the battery can be fully charged and discharged at least 800 times. The lifespan consists of the number of charge cycles and the calendar life. Batteries age even when not in use. However, thanks to the battery management system, lithium-ion batteries last significantly longer. And with proper care, the cells can be used for a longer period. If performance decreases, the first thought should be of a repair.

Ampere is the Unit of Measurement for Current

The battery capacity is indicated in ampere-hours. The amount of current stored in a cell. The more ampere-hours (Ah) a battery has, the longer it can be used. The ampere-hours are also referred to as the nominal capacity.

An example: A battery has a capacity of 10 Ah. This means that you can draw 1 ampere-hour from a battery for 10 hours.

Watt is the Unit of Measurement for Power

The watt-hour (Wh) on a battery indicates the energy it can deliver under certain conditions. The watt-hour is also referred to as the nominal power. If a battery delivers one watt of energy in an hour, it delivers one watt-hour. The watt-hour of a battery is calculated as voltage x capacity.

Example: The battery description states 25V and 18Ah. Therefore: 18Ah x 25V = 450Wh.

Volt is the electrical voltage of a cell or battery. The voltage is created by the interaction of electrons in the cell. The nominal voltage of lithium-ion batteries is 3.6V (LiFe) and 4.2V (LiMa, LiPo).

To clarify the terms, let's take the bestseller product from Makita. The cordless drill driver with the following product designation: DDF482RFJ 18 V / 3.0 Ah, 2 Batteries + Charger in MAKPAC.

The cordless drill driver is a model from the 18 V series by Makita. 18 V stands for 18 volts in this case. This cordless drill driver is a set that includes two 3.0 Ah batteries. This means these batteries have 3.0 ampere-hours.