Battery Chemistry Glossary for Robotics Buyers

The handful of battery terms that actually show up on robot spec sheets, decoded.

The core terms

Energy density: how much energy a battery stores per unit of weight or volume — the key number determining runtime for a given battery size. C-rate: how fast a battery can safely charge or discharge relative to its total capacity — a higher C-rate battery can deliver bursts of power more easily.

More terms worth knowing

Cycle life: how many full charge-discharge cycles a battery can undergo before its capacity degrades to some threshold, commonly 80% of original capacity. Depth of discharge (DoD): how much of a battery's capacity is used before recharging — shallower discharge cycles generally extend a battery's overall lifespan. Thermal runaway: the dangerous self-reinforcing overheating failure mode that battery safety systems are designed to prevent.