Why We Should Fully Charge LFP Batteries Every Week

When considering the maintenance of Lithium-ion batteries, especially those composed of lithium iron phosphate (LFP), periodic full charging becomes a critical practice. This article explores the reasons behind this recommendation and discusses the importance of balancing battery longevity with usage efficiency.

Understanding LFP Batteries and Their Maintenance

Given the intricacies of battery technology, it is imperative to address a common question: Why should we charge LFP batteries to 100% every week? Scott's insight holds true, as the state of charge (SOC) of LFP batteries can drift over time, and the flat discharge curve makes it challenging to accurately determine the SOC based solely on battery voltage. To recalibrate the SOC, cells must be charged to a voltage threshold such as above 3.45V, typically requiring a 95 full charge per cell. This process also facilitates cell balancing, which is essential for maintaining the overall health and performance of the battery.

The Impact of Battery Discharge on Lifespan

Keeping LFP batteries fully charged, particularly lithium-based batteries, maximizes their lifespan. Batteries that are frequently discharged suffer from a gradual degradation of their cells, leading to a reduction in the charge capacity they can hold. For many lithium-based batteries, including LFP, maintaining a full charge can extend cycle life significantly. Studies have shown that discharging to 50% and charging back to 100% typically results in around 6,000 cycles before the battery becomes largely ineffective. Discharging to as low as 20% and then fully recharging can only result in about 2,000 cycles, significantly prematurely shortening the battery's lifespan.

Continuous Capacity Loss and Leak Management

LFP cells experience a slower rate of capacity loss and have a longer recycle life compared to other lithium-based alternatives, such as those incorporating cobalt or nickel. LFP batteries utilize iron and phosphorus, which are more plentiful in the earth's crust than cobalt and nickel. This abundance can be advantageous in terms of reducing environmental impact and cost.

Nevertheless, these batteries are prone to "leakage," where the charge naturally dissipates over time, even if the battery is not in use. Staying at a full charge mitigates this issue, preventing the battery from degrading to detrimental levels. While the longer cycle life of LFP batteries compared to other lithium types, such as Nickel Manganese Cobalt (NMC), is evident, it is essential to note that frequent deep-discharge cycles can still shorten the battery's useful life.

Comparative Analysis: LFP vs. Other Lithium-Ion Batteries

The graphical representation clearly shows that the discharge capacity retention of LFP batteries far exceeds that of NMC batteries. Under strict test conditions, commercially available LFP cells were repeatedly discharged and charged from 0 to 100%, demonstrating a significantly longer cycle life span. This enhanced longevity is due to the lower rate of capacity loss experienced by LFP batteries during recharge cycles. Other lithium-ion batteries, such as those using a 0 to 100% charge cycle at higher rates, often suffer from shorter cycle lives as they are more prone to overheating during charging, which can lead to premature failure. This tradeoff can also increase the cost of the battery unit due to the need for more advanced cooling systems.

Conclusion: Regularly fully charging lithium iron phosphate (LFP) batteries is crucial for maintaining their optimal performance and longevity. This practice helps manage the natural leakage and minimizes degradation, ensuring that your battery remains effective for as long as possible. While LFP batteries may be marginally more expensive than some alternatives, their superior cycle life and lower risk of overheating make them a worthwhile investment for those looking to extend the lifespan of their batteries significantly.