There are YouTube videos and articles claiming that limiting charging to 90% is ineffective and unnecessary. While it might seem frustrating, this practice is indeed effective. Some people argue that due to cell balancing, charging to 100% isn't actually reaching full capacity, or that manufacturers build in a margin so 100% isn’t truly 100%. However, even if one parallel cell group in a series of cells has a lower capacity, the battery can still charge and discharge from 100% to 0%. Therefore, cell balancing isn't a major concern in this context. In fact, if a manufacturer fails to properly account for this in parallel cell groups within series cells, it points to larger issues in their battery management system (BMS).
Manufacturers try to minimize the margin between the displayed charge percentage and the actual battery capacity because driving range is a critical performance indicator. However, if the margin is too small and doesn’t account for potential errors in calculating battery capacity, it can lead to problems.
Limiting charging to 90% can help mitigate issues related to errors in estimating the remaining battery capacity. Companies with less advanced BMS technology might have higher error rates in their calculations, but reducing the charging limit can help manage these risks by providing a buffer. This is particularly important for extending the overall lifespan of the battery, as charging to 100% regularly can accelerate battery degradation over time.
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