What effect do cold temperatures have on car batteries?
Cold temperatures are a double-edged sword for conventional lead/acid batteries: The battery’s performance declines dramatically at freezing temperatures, while at the same time the starter needs considerably more power to overcome greater oil viscosity and crank the cold engine started. On the other hand, temperatures above +50 degrees Celsius in a battery are harmful and shorten its life. This illustration shows the relationship: Although a brand-new lead/acid battery can deliver 100-percent cranking power at a warm +20 degrees Celsius, its capacity drops to a mere 40 percent at a frigid -20 degrees Celsius. At the same time, however, more than twice the energy is needed to start the cold engine.
