•A calorimetry method for heat generation measurement of batteries is presented.•Method is based on lumped capacitance model and forced convection environment.•Effects of current and temperature on heat generation characteristics are measured.•The effect of cycle aging on heat generation characteristics is measured.•The effect of cycle charge current on battery cycle life is significant. This paper presents a forced convection calorimetry method, based on the lumped capacitance model, to measure the continuous noise-free heat generation rate of batteries. The method was verified via reference sample calibration. Battery test results indicated that the discharge current, ambient temperature, and cycle aging significantly affect the heat generation characteristics of batteries. A larger discharge current and lower ambient temperature of 20–45 °C caused a greater heat generation rate and faster temperature increase. The average heat generation rate over the discharge period exhibited a quadratic polynomial correlation with the discharge current and a negative quadratic polynomial correlation with the ambient temperature. The cycling process increased the heat generation rate, reflecting battery aging. The cycle charge rate had a significant impact on the battery life. Moreover, the two cells started to display different heat generation characteristics after being cycled by different currents even at a similar state of health, revealing that the cycling process and different cycle rates may aggravate the battery inconsistency.