In the example file Julien mentions, you can find the following object classes which describe the charging and discharging coefficients for the battery.Â
 Curve:DoubleExponentialDecay,
  Doubleexponential,    !- Name
  1380,           !- Coefficient1 C1
  6834,           !- Coefficient2 C2
  -8.75,          !- Coefficient3 C3
  6747,           !- Coefficient3 C4
  -6.22,          !- Coefficient3 C5
  0,            !- Minimum Value of x
  1,            !- Maximum Value of x
  ,             !- Minimum Curve Output
  ,             !- Maximum Curve Output
  Dimensionless,      !- Input Unit Type for x
  Dimensionless;      !- Output Unit Type
 ElectricLoadCenter:Storage:Battery,
  Kibam,          !- Name
  ALWAYS_ON,        !- Availability Schedule Name
  ,             !- Zone Name
  0,            !- Radiative Fraction
  10,            !- Number of Battery Modules in Parallel
  10,            !- Number of Battery Modules in Series
  86.1,           !- Maximum Module Capacity {Ah}
  0.7,           !- Initial Fractional State of Charge
  0.37,           !- Fraction of Available Charge Capacity
  0.5874,          !- Change Rate from Bound Charge to Available Charge {1/hr}
  12.6,           !- Fully Charged Module Open Circuit Voltage {V}
  12.4,           !- Fully Discharged Module Open Circuit Voltage {V}
  charging,         !- Voltage Change Curve Name for Charging
  discharging,       !- Voltage Change Curve Name for Discharging
  0.054,          !- Module Internal Electrical Resistance {ohms}
  100,           !- Maximum Module Discharging Current {A}
  10,            !- Module Cut-off Voltage {V}
  1,            !- Module Charge Rate Limit
  Yes,           !- Battery Life Calculation
  5,            !- Number of Cycle Bins
  Doubleexponential;    !- Battery Life Curve Name
 Curve:RectangularHyperbola2,
  charging,         !- Name
  -.2765,          !- Coefficient1 C1
  -93.27,          !- Coefficient2 C2
  0.0068,          !- Coefficient3 C3
  0,            !- Minimum Value of x
  1,            !- Maximum Value of x
  -100,           !- Minimum Curve Output
  100,           !- Maximum Curve Output
  Dimensionless,      !- Input Unit Type for x
  Dimensionless;      !- Output Unit Type
 Curve:RectangularHyperbola2,
  discharging,       !- Name
  0.0899,          !- Coefficient1 C1
  -98.24,          !- Coefficient2 C2
  -.0082,          !- Coefficient3 C3
  0,            !- Minimum Value of x
  1,            !- Maximum Value of x
  -100,           !- Minimum Curve Output
  100,           !- Maximum Curve Output
  Dimensionless,      !- Input Unit Type for x
  Dimensionless;      !- Output Unit Type