c1 = LineChart()
c1.title = "SLA Discharge - 5.5A: V_BAT"
c1.style = 12
c1.y_axis.crossAx = 500
c1.x_axis = DateAxis(crossAx=100)
c1.x_axis.number_format = 'd-HH-MM-SS'
c1.x_axis.majorTimeUnit = "days"
c1.y_axis.title = "Battery Voltage"
c1.x_axis.title = "Time"
data = Reference(ws2, min_col=2, min_row=1, max_col=2, max_row=sheet.max_row)
c1.add_data(data, titles_from_data=True)
dates = Reference(ws2, min_col=1, min_row=2, max_row=sheet.max_row)
c1.set_categories(dates)

c2 = LineChart()
data2 = Reference(ws2, min_col=3, min_row=1, max_col=3)
c2.add_data(data2, titles_from_data=True, from_rows=True)

c2.y_axis.axId = 200
c2.y_axis.title = "Qbat Percentage"
c1.y_axis.crosses = "max"
c1 += c2


s1 = c1.series[0]
s1.graphicalProperties.line.solidFill = "BE4B48"
s1.graphicalProperties.line.width = 25000 # width in EMUs.
s1.smooth = True # Make the line smooth
ws2.add_chart(c1, "D5")