The lead-acid battery has been a reliable, cost-effective solution in the world of energy storage for years. These batteries come into use across industries, from automobiles to backup power systems. However, with all their benefits comes a lurking danger that lurks but raises safety and performance concerns: thermal runaway. In this article, we will discuss thermal runaway in lead-acid batteries, why it happens, and how to prevent it.

Thermal Runaway Defined

Thermal runaway means an eventual self-reinforcing process in which the temperature of a battery cell or pack rises uncontrollably because of multiple internal factors. Once the heat generated exceeds the heat dissipation capacity, a vicious cycle is started, and this lead to an escalation of temperature that can finally result in battery failure, leakage, or even explosion. A better understanding of its causes will reduce its risks effectively if known.

Causes Of Thermal Runaway In Lead Acid Batteries

A. Overcharging And Its Effects On Battery Temperature

Overcharging takes place when a battery is charged at voltages that are greater than the recommended ones. While the amount of charging required to maintain the battery’s charge state remains acceptable, excessive charging accumulates extra energy in the battery. This extra energy gives rise to heat, which instigates a temperature increase in the battery. The battery’s chemistry gets unstable, increasing its heat generation rate, eventually leading to thermal runaway. Hence proper charging methods are essential to avoid getting into this scenario.

B. Internal Short Circuits and their Contribution to Thermal Runaway

Internal short circuits happen through the separator being compromised between a battery’s positive and negative plates. This can be via physical damage or manufacturing defects, among other causes. Consequently, direct electrical connection forms between the plates with a rapid current flow. This excess current encourages excessive heat buildup, which can be quickly raised to high temperatures that may speedily superheat the battery. Internal short circuits intensify thermal runaway risks by increasing the battery’s inner resistance and uncontrolled reactions. Regular battery inspections and maintenance prove helpful in spotting them early enough to rectify them before they get out of hand.

C. Electrolyte Drying and Its Effect on Battery Heat Generation

The electrolyte within a lead-acid battery serves as an important medium for ion exchange, enabling the battery’s operation. However, the electrolyte can slowly evaporate under some circumstances, such as high temperatures or continued operation. Lesser electrolyte levels hinder efficient heat dissipation and the consequence is that the battery’s internal temperature will rise. This increase in temperature increases chemical reactions within the battery resulting in accelerated aging and possibly initiating thermal runaway happening upon unattended monitoring and maintaining appropriate electrolyte levels.

How to Avoid Situations That Will Lead to Thermal Runaway

In lead-acid batteries, a combination of proactive measures might be used to prevent thermal runaway:

  • Charging Control: Obey suggested charging voltages and durations from the manufacturer in order to preclude overcharging.
  • Routine Inspections: Routinely check for physical damage on the batteries, electrolyte loss, or corrosion.
  • Temperature Monitoring: The temperature monitoring systems should be applied to detect the abnormal rise in temperatures immediately.
  • Proper Ventilation: Install batteries in well-ventilated areas to facilitate heat expulsion.
  • Maintenance: Clean and maintain battery terminals and connections regularly to reduce resistance and increase heat generation.

The Bottom Line

Thermal runaway is a great threat to the safety and life of lead-acid batteries. By understanding the causes and adopting preventive measures, users can fully use the benefits provided by lead-acid batteries while minimizing risks associated with thermal runaways. The potential risk involved in catastrophic failures can be significantly reduced through appropriate usage, monitoring, and maintenance, thereby ensuring a safer posture on the reliability of energy storage solutions.