For thermal runaway to occur in vented lead-acid batteries, very high extremes of charging current and the resultant high temperature must be present. While this document only considers thermal runaway in VRLA AGM products many of the causes are also applicable to GEL types.
SLA batteries taken to high DoD can experience accelerated sulfation rates which in rare cases can lead to thermal runaway through excessive heat build up due to higher demand on an underperforming battery. Now that we have covered thermal runaway in SLA, you may be wondering about thermal runaway in lithium 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.”
In lithium-ion batteries, thermal runaway is especially concerning because of the highly reactive nature of lithium. Once thermal runaway begins in a single cell, the heat and pressure buildup can spread to adjacent cells in a battery pack, escalating into a large-scale event known as “Thermal propagation.”
Lead-acid batteries, which are commonly encountered by many people, have several issues that are not well understood. One of the least understood problems is their susceptibility to thermal runaway. The Wikipedia provides a useful definition of this phenomenon.
Thermal runaway is a dangerous phenomenon in which a battery’s temperature rapidly escalates uncontrollably, often leading to fires or explosions. Understanding the mechanisms behind thermal runaway and its implications is essential for improving battery safety and preventing catastrophic failures in systems that rely on batteries.