Battery knowledge · Capacity, energy, power and ratings
Nominal voltage
A representative average voltage of a cell over a full discharge, such as 3.6–3.7 V for an oxide/graphite cell or about 3.2 V for LFP/graphite. Multiplied by capacity, it gives nominal energy.
- Unit
- V
Example
Voltage under load
5 A through 20 mΩ gives 0.1 V ohmic drop.
Chosen OCV curve; no chemistry calibration, hysteresis or voltage cutoff.
Explore the graph
Discharge current creates an ohmic drop below open-circuit voltage.
5 A through 20 mΩ gives 0.1 V ohmic drop.
V_terminal = OCV − I_discharge R
Illustrative model. Chosen OCV curve; no chemistry calibration, hysteresis or voltage cutoff.
Use in Lemonergy
Lemonergy Core equation
Estimate nominal energy
Lemonergy Core evaluates this relation.
Equation or tool to use
- nominal_energy_wh
Core equation
Inputs & settings
- Capacity (Ah)
- Nominal voltage (V)
This overview identifies the components to use. Follow the example in Lemonergy for their connections and settings.
- Open the lesson and inspect the equation.
- Change one input while holding the others fixed.
Example. A 5 Ah cell rated 3.6 V has 18 Wh nominal energy. Ten identical cells contain 180 Wh nominally.
Observe. Compare the result with the equation and units.
This is a rating estimate, not integrated delivered terminal energy.
Open the worked lesson →References & further reading
Further reading on this topic
These sources provide broader context; they are not presented as citations for every statement in this entry.
- The International System of Units (SI), 9th edition
Bureau International des Poids et Mesures · 2026
Topic background · Definitions of SI units and coherent derived units; 2026 revision.
- Battery Test Manual For Electric Vehicles, Revision 3
Jon P. Christopherson · Idaho National Laboratory · 2015
Topic background · Performance characterization, pulse resistance/power, life testing and reference performance tests; historical 2015 edition.