Compression Pad Selection
How to select a battery compression pad: start from the BOL and EOL pressure window, size thickness for cell growth, and compare PU, silicone and EVA on compression set, stress relaxation and temperature.
ageing
Nanoscale Elastic Coatings
During the charge / discharge the cathode and anode undergo an expansion and contraction. As you charge a cell it expands, when you discharge a cell it contracts and as the cell ages over its lifetime we see a continuing cell expansion. Thus the cell expansion can be divided into: This expansion and contraction puts … Read more
Calendar Ageing vs Chemistry
How do different battery chemistries compare in terms of calendar ageing? When we look at battery lifetime the standard method used by industry has two fundamental test regimes as inputs: Here we are focussing on the Calendar Ageing, this is all about how the cell ages just left on a shelf doing nothing. Dubarry et … Read more
LFP Cell Clamping Pressure
The LFP cell clamping pressure is important as it keeps the active layers in contact. However, we have to remember that LFP cells expand over their lifetime by 10 to 20% in thickness and during charge / discharge they expand / contract respectively. Hence there is an irreversible and reversible aspect to cell expansion. Here … Read more
Unlocking Unlabelled Battery Field Data
How can we unlock the full potential of vast, unlabeled battery field data? Despite significant advancements achieved by data-driven methods, diagnosis accuracy remains constrained by the high costs of check-up tests and the scarcity of labeled data. In this paper experimental verification is performed on the battery degradation dataset from 20 commercial EVs, collected over … Read more
Developing a Lifecycle Test Procedure
Where to start with the task of developing a lifecycle test procedure. Battery cell ageing is such a complex subject that it makes it difficult to know where to start. One of the first things to do is to break the problem into Calendar and Cycle Ageing. Now we know we are going to be … Read more
Cycle Life and Energy Density
Is there a relationship between Cycle Life and Energy Density? This is a mix of chemistry, age, size and manufacturers. Hence a lot of other information mixed into this, but there is a trend. Adding trendlines might be generous, but what we can see is that low energy density cells range in cycle life from … Read more
Remaining Useful Life
What is Remaining Useful Life (RUL)? Remaining Useful Life (RUL) is a key function declared by the battery management system. As per the title it gives you the remaining predicted lifetime of the battery based on its usage and degradation to the failure threshold [1]. It represents the period from the observation to the end of life … Read more
Knee Point
Attia et al [1] also describe six mechanisms/pathways that can produce the “Knee Point”: The impact of this nonlinear degradation in cell capacity depends to some extent on the architecture and application, but includes: This post has been built based on the support and sponsorship from: Eatron Technologies, About:Energy, AVANT Future Mobility, Quarto Technical Services, TAE Power Solutions and The Limiting Factor. … Read more
Cell Balance and End of Life
In any battery pack design it is only as strong as the weakest link [4], one bad cell or group of cells in the series string will control the total power and energy available from the pack. This means it is important to match the cells and to keep them balanced throughout the lifetime use … Read more