ClueLuma

Battery ending state of charge calculator

Subtract the DC energy withdrawn as a capacity fraction; do not subtract AC energy without conversion.

SOCend=SOCstart−EDCEnom×100\mathrm{SOC}_{\text{end}} = \mathrm{SOC}_{\text{start}} - \frac{E_{\text{DC}}}{E_{\text{nom}}} \times 100

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

%
kWh
kWh
%

Worked example

Given

  • SOCstart\mathrm{SOC}_{\text{start}} = 85 %
  • EDCE_{\text{DC}} = 180 kWh
  • EnomE_{\text{nom}} = 600 kWh
SOCend=85−180600×100=55\mathrm{SOC}_{\text{end}} = 85 - \frac{180}{600} \times 100 = 55

Symbols and units

SymbolMeaningUnit
SOCend\mathrm{SOC}_{\text{end}}ending state of charge%
SOCstart\mathrm{SOC}_{\text{start}}starting state of charge%
EDCE_{\text{DC}}energy withdrawn from batterykWh
EnomE_{\text{nom}}reference DC capacitykWh

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Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.