Voltage – the mathematical measurement of voltage is:
V (voltage) = I (current) x R (resistance)
Voltage measures is the difference in electric potential between the negative and positive terminals of a battery. A larger difference in potential results in a higher voltage. Voltage is determined by the chemical make up of the battery, the battery components and the polarization of the battery.
The cell voltage of a lead acid battery, for example, is just over 2 while some types of lithium ion cells offer nearly twice this.
To understand the role of voltage in electrical circuits it can be helpful to imagine the flow of electrons passing through a wire in the same way as water flows through a pipe.
- Current is the flow,
- Resistance is the drag where the water is pushing against the pipe edges,
- Voltage is the water pressure.
In this way it is easy to see voltage indicates how quickly a battery can deliver its stored energy. A photographer who needs rapid flash recharges would look for a higher voltage battery while a remote control needs no such power push to operate.
There are four unique voltage types:
- Float Voltage – the voltage a battery should be kept at when in storage (Secondary batteries only).
- Nominal Voltage – the voltage stated on the battery case or in its technical specification sheet which can vary slightly from the actual voltage of the battery.
- Charge Voltage – the voltage of the battery when it is fully charged or the voltage available from a battery at any point during its recharge (Secondary batteries only).
- Discharge Voltage – the voltage available from a battery at any point during its discharge.