Thermal characteristics of the nickel-metal hydride cell

The heat dissipation characteristics of a nickel-metal hydride (Ni-MH) cell during charge, discharge, and overcharge were determined by using radiative-type calorimetry. A hermetically sealed cell of prismatic design and 6.5-Ah capacity was prepared for this study. The cell dissipated negligible heat during charge at C/10 until it reached an overcharge condition, at which point the heat rate was 0.75 W. The average heat rate during discharge at C/2 rate was 0.35 W. The heat rate measured during discharge was used to calculate a thermoneutral potential of 1.362 V.