I was about to start reading about the reliability engineering topic and came across this failure of an car battery as a starting example which reminded me of the car battery failure I have seen. One day car didn't start and realized that car was absolutely dead. I cursed the car manufacturer as well as the battery manufacturer as it was not many years ago battery was replaced and I expected few more years of life for the battery. Started asking about the failure scenarios and MTBF of the car battery and the mechanic explained me that it is supposed to last for >5 years and again life depends on usage. Then my frustration grew more as I had a life of only 2 years and it did not pass the expected "normal life". Even the "probability" of failure scenarios didn't convince me. Then I being an electronics engineer started thinking how does the MTBF work? Are all the equipment produced work till expected timelines? Are my products guaranteed life time based on MTBF value? None gave me an answer as my analysis on my products always leads to a good MTBF value. The new question that came to mind was can MTBF be applied to car battery case as it is not repairable?
Then after reading the reliability definition, "Reliability is the ability of an asset or component to perform its required functions under certain conditions for a predetermined period of time.", I understood that there is a caveat here. Reliability analysis done by engineers is under certain conditions and if conditions are not followed what happens to the system was not thought of. Then thinking of the car scenario, I realized that I used car tyre inflator without turning ON the engine which drained my battery. This I used not just once but many times and one day battery was dead. Battery was dead within the life time defined by the manufacturer. It wasn't manufacturer issue but definitely end usage issue. Even as a electronics engineer, covering these kind of scenarios are very difficult.
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