Battery knowledge · Capacity, energy, power and ratings
Ideal duration
t = 1 / C-rate: how long a constant current would take to transfer the full nominal capacity. A definition, not a prediction of real runtime. [1]
- Unit
- h
- Relationship
- t = 1 / C-rate
Example
Estimate an ideal duration
At 0.5C, an ideal full-capacity constant-current discharge takes 1 / 0.5 = 2 h. A real discharge can end earlier at its voltage limit; CC-CV charging includes a taper and does not follow this duration alone.
Explore the graph
A C-rate becomes an actual current only when capacity is known.
5 Ah × 1C = 5 A. Ideal duration: 1 h (60 min).
I = Q × C-rate; t_ideal = 1 / C-rate
Illustrative model. Voltage cutoff, losses, temperature and rate-dependent capacity are excluded.
Use in Lemonergy
Lemonergy Core equation
Compare ideal duration
Lemonergy Core evaluates this relation.
Equation or tool to use
- ideal_duration_hours
Core equation
Inputs & settings
- Positive C-rate
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. At 0.5C ideal full-capacity duration is 2 h; at 2C it is 0.5 h.
Observe. Compare the result with the equation and units.
This excludes CV taper, cutoff, rate-dependent capacity and rest.
Open the worked lesson →References & further reading
Technical references
- DOE Energy Storage Handbook, Chapter 16: Energy Storage Performance Testing
Sandia National Laboratories
Technical reference · Section 2.1.2.1 explains capacity, C-rate and the distinction between capacity and energy; also covers pulse characterization.
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.