The four main causes of battery failure

Batteries and rechargeable batteries are essential components in many devices, vehicles, and systems that we use every day. But how reliable are they really, and what are the main causes of battery failure?

In this article, we discuss four key factors that influence battery lifespan and performance: temperature, depth of discharge, charging rate, and aging.

The optimal battery temperature

Temperature is one of the most critical factors affecting battery performance. Temperatures that are too high or too low can disrupt the chemical reactions inside the battery, affecting capacity, voltage, and internal resistance.

In extreme situations, high temperatures can lead to thermal degradation, gas formation, leakage, or even battery failure and explosion.

The optimal operating temperature depends on the battery type and application. In general:

• Lithium-ion batteries perform best around room temperature (20–25 °C)
• Lead-acid batteries tolerate higher temperatures better, up to approximately 50 °C

At low temperatures, the available battery capacity decreases for both technologies. Lithium-ion batteries often recover once warmed up again, while lead-acid batteries may suffer permanent capacity loss.

To minimize temperature-related damage, batteries should ideally be stored and used in a stable, moderate-temperature environment. It is also important to avoid overcharging and deep discharging, as both can increase internal heat generation.

Depth of discharge (DoD)

Depth of discharge (DoD) indicates how much of a battery’s total capacity is used before recharging.

A high DoD allows more energy usage per cycle but also increases battery wear. A lower DoD generally extends battery lifespan.

The optimal DoD depends on battery chemistry:

• Lithium-ion batteries are generally more resistant to deep discharge and can often safely discharge up to 80% of capacity
• Lead-acid batteries are typically limited to around 50% discharge to prevent excessive wear

In general, the deeper the discharge cycle, the fewer total charge cycles the battery can achieve over its lifetime.

To extend battery lifespan, it is recommended to keep the DoD as low as practical while still meeting the application’s energy requirements.

Regular charging to an optimal level — often between 80% and 95% depending on the battery type — also helps preserve capacity and longevity.

Battery charging speed

Charging speed is usually expressed as the C-rate. A higher C-rate means the battery charges faster but also experiences more stress and heat generation.

A lower charging rate is gentler on the battery and generally improves long-term performance.

Typical charging behaviour differs by battery type:

• Lithium-ion batteries can usually charge relatively quickly, often at a C-rate between 0.5C and 1.0C
• Lead-acid batteries generally require slower charging rates around 0.1C to 0.2C

Exceeding recommended charging speeds may lead to overheating, gas formation, leakage, or permanent damage.

To optimize battery performance and safety, the charging rate should always be adapted to the battery technology and application requirements.

It is also important to avoid both overcharging and undercharging, as these conditions negatively affect lifespan and capacity retention.

Battery aging

Aging is the gradual loss of battery capacity and performance over time. This process is unavoidable and influenced by several factors, including:

• Temperature
• Depth of discharge
• Charging speed
• Battery materials and design
• Manufacturing quality

In general, lithium-ion batteries offer a longer lifespan than lead-acid batteries, although they may age faster under unfavourable conditions.

For example:

• A typical lithium-ion battery may lose around 20% of its capacity after approximately 500 cycles
• A typical lead-acid battery may lose around 30% after roughly 200 cycles

Battery aging tends to accelerate as capacity decreases.

To slow down aging, batteries should be properly maintained and protected against extreme temperatures, overcharging, and deep discharge conditions.

Eventually, batteries should be replaced or recycled once they no longer meet the required performance levels

Conclusion

Batteries are complex and sensitive energy systems influenced by multiple external and internal factors. By understanding these factors and applying proper charging, storage, and maintenance practices, battery reliability, safety, and lifespan can be significantly improved.

Would you like more information about preventing battery failure or advice on selecting the right battery for your application? Feel free to contact Elfa. Our specialists are happy to help you find the best solution.