Battery knowledge · Capacity, energy, power and ratings
Resistance–capacity product
A cell’s internal resistance multiplied by its capacity, which cancels out size: ten 5 Ah, 20 mΩ cells in parallel make 50 Ah at 2 mΩ, both 100 mΩ·Ah. Lower values mean more power per unit of stored energy. Conductance divided by energy, in siemens per watt-hour, expresses the same figure of merit the other way up.
- Also called
- ohm-ampere-hour, mΩ·Ah, siemens per watt-hour, S/Wh
- Unit
- mΩ·Ah
- Relationship
- R·Q (mΩ·Ah); G/E = 1/(R·E) (S/Wh)
Example
Compare two cell sizes
A 5 Ah cell with 20 mΩ resistance and a 10 Ah cell with 10 mΩ resistance both have RQ = 100 mΩ·Ah. Compare like test conditions; identical RQ does not imply identical chemistry or thermal behavior.
Explore the graph
Identical parallel cells reduce resistance while adding capacity.
R × Q remains 100 mΩ·Ah. Ten parallel cells give 2 mΩ and 50 Ah.
R_parallel = R_cell/N; Q_parallel = N Q_cell; R_parallel Q_parallel = R_cell Q_cell
Illustrative model. Only integer cell counts represent packs; lines show the scaling trend between them. Series resistance of busbars and joints is omitted.
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.