Battery knowledge · Units and electrical basics
Ampere-hour
A unit of electric charge: one ampere flowing for one hour, or 3600 coulombs. Battery capacity is rated in ampere-hours, which measure charge, not energy. [1]
- Abbreviation
- Ah
- Also called
- amp-hour
- Unit
- Ah
Example
C-rate, current and duration
5 Ah × 1C = 5 A. Ideal duration: 1 h (60 min).
Voltage cutoff, losses, temperature and rate-dependent capacity are excluded.
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
Convert C-rate into current
Lemonergy Core evaluates this relation.
Equation or tool to use
- current_from_c_rate
Core equation
Inputs & settings
- Capacity (Ah)
- C-rate (1/h)
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 at 0.5C corresponds to 2.5 A. At 2C it corresponds to 10 A.
Observe. Compare the result with the equation and units.
Current magnitudes do not establish safe charge rates.
Open the worked lesson →References & further reading
Technical references
- The International System of Units (SI), 9th edition
Bureau International des Poids et Mesures · 2026
Technical reference · Definitions of SI units and coherent derived units; 2026 revision.