Have you ever wondered “why” your battery stops working? All batteries fail at one point or another and more importantly all batteries fail - due to different reasons. Specifically, two identical batteries that come from the same manufacturing batch, with the same identical voltage, capacity, and chemistry fail (or stop working) at different times. Why? To understand why batteries fail I will walk through the steps of a battery mode and effects analysis to discover modes of battery failure and the effects of the battery failure.
A battery mode and effects analysis is a procedure for identifying and understanding potential failure modes in a battery system. A battery mode and effects analysis contains four main steps or phases:
- Battery Mode Pre-work
- Battery Failure Severity
- Battery Failure Occurrence
- Battery Failure Detection
Battery Mode Pre-work
The Battery Mode Pre-work is an essential preliminary component to a battery mode and effects analysis and often times the one component that gets the least attention. It is a way of “starting smart” in the identification of battery failures. As an example, battery failures are often caused by shared interfaces. If an engineer, focused on a single facet of the battery’s micro or macro system, glosses over the effectiveness and efficiency of interfacing components when designing, compiling and assembling a battery’s system, then the failure rate and severity could dramatically increase regardless of how “correct” the engineer’s portion of the system is working. A really good case study on shared interface failures is the battery interface with the device’s operating system. The inefficiency of the operating system’s software in a device can under or over utilize the maximum capacity and voltage of a battery and thus subsequently degrade the battery faster then normal. At the consumer level they would just say the battery is bad or “sucks” when in fact it is the device’s software that is the culprit of faster than normal battery degradation.
Thus careful attention to a battery’s mode pre-work is well advised. Battery mode pre-work includes a complete and detailed description of the battery’s system, the battery’s function, the battery’s intended uses, and the probable unintended uses.
In part 2 of Battery Failure Mode and Effects Analysis I will address Battery Failure Severity and Battery Failure Occurrence.