LiPo Battery Voltage and State of Charge
- Michael Botros
In a LiPo battery, a nominal voltage is advertised and we assume that the battery stays at this voltage all the time. These voltages can be seen below and have the following naming conventions.
In reality however, this voltage is not constant and may vary slightly depending on external things like temperature and also the state of charge of the battery for example. The battery voltage can actually hover a bit higher and lower than the nominal voltage. An example chart below shows the voltage of different LiPo battery voltages at different states of charge. Normally a 1S battery should be 3.7V but at 100% charge it can be up to 4.2V which is quite a significant voltage difference.
Typically this voltage change is determined by electrochemical processes such as chemical reactions in the battery, the concentrations of the battery components, and the polarization of the battery.