The parasitic reactions that occur in lithium/silver vanadium oxide cells have been investigated by microcalorimetry. Reactions between lithium and components of the electrolyte are the biggest contributors to beat output. The rate of parasitic reaction of lithium needs to be known to ensure that the batteries are not anode-limited. This parameter is one of many included in a calculation of the balance of materials in the cell. This calculation ensures the proper balance of electrodes and electrolyte solution in a constrained volume and also determines electrode dimensions.