Interesting battery voltage facts

Battery voltage: Interesting facts

A number of factors affect the voltage in batteries;

  • State of charge
  • Temperature
  • Age

When simplified, the internal resistance of a battery will determine the battery’s voltage, which the charge controller will then use to determine whether it needs to be charging or discharging.

As current moves through the cell during either charge or discharge cycles, the cell’s voltage changes as a result of changes in the cell’s internal resistance. Current means the rate of electron flow through the battery caused by either charge or discharge. Every electro-chemical cell has an internal resistance. When the cell is being recharged, current flow causes the cell’s voltage to rise. The higher the recharging current the higher the voltage rise. As the cell is discharged, the discharging current causes the cell’s voltage to drop. While absolute values vary widely between different acid and alkaline technologies, the relationship between current flow and cell voltage remains constant.

Document references that may also be of interest:
  1. The complete battery book Richard A. Perez
  2. Battery Charger Efficiency and Voltage Behaviour in Vented Lead Acid Batteries in Kenya | Daniel Morogo Rutto* School of Engineering, University of Rwanda, P.O. Box 57, Nyagatare, Rwanda | Email:
  3. Battery Performance Characteristics |


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Image of an engineer standing at a commercial solar PV site


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