Battery Discharge Capacity Calculation by Temperature Measurement

Battery capacity is measured in the unit of miliampere hour (mAh) (current x time). In order to do this, the discharge current of a battery is measured and integrated (multiplied) over the duration of the discharge. This paper proposes a method to calculate battery capacity by first measuring the temperature of a load resistor which is used to discharge the battery. The load resistor has a known/characterized Thermal Resistance $(\mathrm{R}_{{\mathrm {th}}})({\mathrm {degC.{W}^{-1}}})$ value. The temperature is then integrated over time and solved using a thermal equation and thus obtaining the battery discharge capacity. The benefit of this type of discharge capacity calculation method is a series resistor (which causes a series voltage drop) is not required in the main current path.