Realkapazität

Realkapazität refers to the actual usable or measurable capacity of a device or system, as opposed to its nominal or theoretical capacity. The term is commonly applied to energy storage units such as batteries, supercapacitors, and other storage technologies. It represents the amount of energy a device can deliver or absorb under specific conditions, typically expressed in watt‑hours (Wh) or kilowatt‑hours (kWh) for battery systems.

The calculation of Realkapazität takes into account losses that inevitably occur. These losses include internal resistance, self‑discharge, temperature effects, degradation over time, and conversion inefficiencies in charge/discharge cycles. Because of these factors, the Realkapazität is usually lower than the rated capacity stated on the product specification sheet. For example, a nominal 100 Wh lithium‑ion battery might provide only 80–90 Wh in practice when measured under standardized testing conditions.

Factors influencing Realkapazität are numerous. Temperature extremes can reduce electrode activity, leading to lower output. The depth of discharge (how fully the battery is driven) also affects the effective capacity; deep cycles tend to reduce usable energy faster than shallow ones. Over time, chemical aging, repeated charge/discharge, and over‑charging or under‑charging can degrade the battery’s ability to hold charge, thereby shrinking Realkapazität.

In practice, engineers and users rely on Realkapazität to design reliable systems. Accurate knowledge of usable energy informs sizing of battery banks for backup power, renewable‑energy storage, electric vehicles, and grid‑level balancing. Operational strategies, such as maintaining state‑of‑charge limits, monitoring temperature, and employing battery management systems, help preserve Realkapazität throughout a device’s service life.