Quiz: What Do You Know About Li-ion Battery Management?

The biggest leaps in lithium-ion (Li-ion) batteries — used in everything from electric vehicles to grid-scale energy storage — often come out of innovations in chemistry, materials, construction, and packaging. But tucked inside every battery pack is the battery management system (BMS) that’s becoming equally vital.

Traditionally responsible for ensuring the reliability and longevity of these potent but potentially volatile cells, the BMS now plays a central role in boosting energy density, charging speed, safety, and cycle life — often at the same time — which can be difficult leveraging new chemistries or materials alone.

Maximizing runtime and extending lifespan require a deep understanding of what’s happening inside each cell. Accurately estimating a battery’s internal state is difficult because its actual capacity is constantly changing, shaped by electrochemical reactions occurring within it. Other influential factors include temperature and aging and the amount of power racing into the load.

Due to these inaccuracies, the BMS tends to be conservative, underestimating remaining capacity to avoid overcharging or damaging the cells. This caution, however, leads to stranded capacity, which reduces runtime or requires engineers to oversize battery packs, adding unnecessary cost and weight.

Emerging innovations in BMS hardware and software — especially in new algorithms that can more accurately assess both remaining runtime and cell degradation — have the potential to unlock this unused capacity.

This quiz covers the fundamentals of monitoring and managing Li-ion batteries. It’s slightly longer than the previous one (Quiz: The Basics of Lithium-Ion Battery Behavior), reflecting the complexity of a BMS’s role in balancing several, often-conflicting objectives. For instance, charging algorithms must weigh the urgency of rapid charging against the long-term risks of cell degradation.

After each question, you'll find a brief explanation of the correct answer, along with links to related articles for deeper insight. Good luck!