Battery Capacity: How to Accurately Predict Remaining Battery Capacity and Runtime for Portable Devices

摘要

The most common technique used today for battery-capacity monitoring is coulomb counting, or integrating the current into-and-out of the battery. This works well for new, freshly-charged batteries. However, it is not very effective with the battery's aging and self-discharge. There is no way to measure the self-discharge rate. So, it is usually corrected with a pre-defined self-discharge rate equation. This approach is not very accurate because the self-discharge rate varies from one battery to another, and a single model can not apply to all battery cells.