Temperature effects are discussed in detail. The consequences of high heat impact into the lead-acid battery may vary for different battery technologies: While grid corrosion is often a dominant factor for flooded lead-acid batteries, water loss may be an additional influence factor for valve-regulated lead-acid batteries.
Thermal events in lead-acid batteries during their operation play an important role; they affect not only the reaction rate of ongoing electrochemical reactions, but also the rate of discharge and self-discharge, length of service life and, in critical cases, can even cause a fatal failure of the battery, known as “thermal runaway.”
Lead-acid batteries contain lead grids, or plates, surrounded by an electrolyte of sulfuric acid. A 12-volt lead-acid battery consists of six cells in series within a single case. Lead-acid batteries that power a vehicle starter live under the hood and need to be capable of starting the vehicle from temperatures as low as -40°.
Heat is one of the most important influencing factors for battery's lifetime. According to the Arrhenius equation, the reaction rate is approximately doubled when temperature is increased by 8–10 K . So all chemical reactions—desired or undesired—will be faster at high heat.
Operating lithium-ion cells at low temperatures has been found to deteriorate performance, primarily due to the formation of a solid electrolyte interface (SEI) that can reduce the flow of lithium ions. In addition, at low ambient temperatures, the battery's internal resistance increases, leading to higher heat generation.
Only at very high ambient air humidity (above 70%), water from outside the battery can be absorbed by the hygroscopic sulfuric acid. In summary, the internal temperature of any lead-acid battery (flooded and AGM) should not exceed 60 °C for extended time periods frequently to limit vaporization. 2.1. External and internal heating of the battery