🔋 Understanding Battery Cycles: Extending the Life of Lithium-Ion Batteries

‘Cycle’, a term commonly used to describe the functionality of rechargeable batteries – especially lithium-ion and similar chemistries – is often misunderstood but rarely explained. In the simple sense, a cycle is the process of depleting a battery from a fully charged state to a fully discharged state, and then returning that battery to its fully charged state via recharging. The definition has more nuances, especially when it comes to defining battery health and lifespan. This article looks at what constitutes a cycle for lithium-ion batteries, and why the measure is central to determining how long a battery can last and how it can perform in the process.

Understanding Battery Cycles

A battery cycle refers to a complete use of the charge inside the battery, but that doesn’t necessarily mean a single discharge from 100 percent to zero percent. If a battery is used from 100 percent down to 50 percent, and then charged back to 100 percent and used again from 100 percent down to 50 percent, the two halves of the cycle together comprise a complete cycle. This distinction is important because it directly relates to how the battery’s charge capacity degrades.

Factors Affecting Battery Cycle Life

• Depth of discharge (DoD): Depth of discharge is the ratio of the number of ampere-hours removed from the battery to its rated discharge capacity. Deep cycles (down to 0 percent) can harm the life of the battery more than partial discharges.
• Charging practices: overcharging or charging too quickly can cause the battery to heat up which decreases its life span.
• Temperature: Both high and low temperatures can affect battery chemistry negatively, impacting cycle life.

Maximising Battery Cycle Life

To extend the life of your lithium-ion batteries, consider the following practices: Avoid full discharges when possible. Aim for partial discharges to about 20-40% before recharging. Slow your charging rate If you can, charge slowly. Reserve fast charging for when it’s absolutely necessary. Try to keep and use batteries in a moderate temperature environment. The lower or higher temperature is bad for battery health.

Key Learnings and Actionable Insights

In other words, it helps to know what exactly a ‘cycle’ is when it comes to lithium-ion batteries, so that you can adopt practices that can extend battery life by many years. For homeowners, here are the essentials. However, a ‘cycle’ isn’t one full discharge, but rather the percentage of the battery’s total usage before a recharge. Optimising battery usage and charging practices can extend the battery's life and performance. Environmental conditions, especially temperature, play a crucial role in maintaining battery health.