Blog - LiFePO4

FAQ: Real failure rate for the LFP cells

Question: I have purchased 16 cells. After some time of usage with a finely tuned BMS system, one of the cells started to show different parameters and started loosing the capacity. I wonder what is the real failure rate for such cells. Could such a sudden failure “just” happen or are these types of cells often defective?  Before I used some other brand of cylinder cells, I never experienced any failure. Now I wish to switch to prismatic cells and the problem happens right away. What is your comment?

Answer: First of all, we are sorry you face difficulties with the products purchased from GWL. We will be happy to follow the warranty conditions and provide a replacement for you based on the RMA process according to the manufacturer guidelines. Secondly we are even more sorry that such a failure happens to you just for the first order of the new technology.  During 2014 we distributed 6.8 million Ah of LiFePO4 cells. With average capacity around 50Ah we have distributed more than 100 000 pieces of LFP cells. From this huge quantity per year, we have only about 20 warranty complains about the failure of the technology. This sets the failure rate at about 1 in 5000 cells.

In other words, there is some little chance that there will be a defective cell. The bad luck may be that a customer will meet this failure during the first purchase or a purchase of just a small number of cells. As explained we will try our best to provide a solution according to the instruction from the manufacturer.

In addition we have about 40 complaints per year related to user failures. Such failures are often results of the overcharge, deep discharge, over heating, or other misuse of the cells. These failures are not warranty cases and cannot be covered by the warranty of the manufacturer. However, at GWL, we always try to find a friendly solution even for such cases. We may provide replacement products at discount pricing or some other favorable solution.