Battery knowledge · Capacity, energy, power and ratings
Energy density
Stored energy per unit volume, in watt-hours per litre. It is the figure that matters when space is the constraint, as in a phone or under a car floor; high-energy cylindrical cells pass 700 Wh/L.
- Also called
- volumetric energy density
- Unit
- Wh/L
Example
From charge to energy
5 Ah × 12 V = 60 Wh nominal energy.
Specific energy divides energy by mass; energy density divides it by volume.
Explore the graph
Voltage connects capacity in ampere-hours to nominal energy in watt-hours.
5 Ah × 12 V = 60 Wh nominal energy.
E_nominal = Q_nominal V_nominal; actual energy = ∫ VI dt
Illustrative model. Specific energy divides energy by mass; energy density divides it by volume.
Use in Lemonergy
Separate nameplate ratings from test results.
This is a reference concept. No executable Lemonergy block has been verified for this term.
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.