New Application Note: Designing with Supercapacitors

Abracon’s new guide, Designing with Supercapacitors, explores the various considerations engineers and designers must take into account when implementing supercapacitors in their projects.

Backup power needs can vary dramatically depending on the application. For instance, a laptop's Real-Time Clock (RTC) backup requires very little energy over a few milliseconds. In contrast, a full-house backup needs kilowatts of power over extended periods, from hours to days. When scoping a backup system, several critical questions must be addressed.

First, how long is backup needed? Determine if you need short-term power to save work before shutting down or long-term power to run a home or factory during an outage.

Second, how much work is required? Understanding the total energy needed helps decide the appropriate power source, whether it's batteries, supercapacitors, or a hybrid solution.

Supercapacitors present significant advantages over traditional batteries, especially in terms of durability and safety. They surpass batteries in charge/discharge cycles and lack the thermal runaway risks associated with lithium-ion batteries.

Sizing a Supercapacitor

Properly designing with supercapacitors involves accurate sizing, which requires understanding the load's energy requirements and considering real-life factors like discharge current and Equivalent Series Resistance (ESR).

For example, for a 20W load over 180 seconds, theoretical calculations might suggest a 408-farad capacitor. However, real-world constraints demand a larger capacitor. Discharge current limits are crucial; as voltage drops, current must increase to maintain power output, necessitating limits to prevent supercapacitor damage. Additionally, not all of a supercapacitor's capacity is usable due to internal resistance and voltage derating for longevity. Considering a 2-year lifespan and 30% degradation, a 20W load over 180 seconds may require around 6250 farads, accounting for real-life factors like ESR, voltage derating, and operational tolerances.

For an in-depth understanding, including equations and practical examples, read Abracon’s full guide on Designing with Supercapacitors. This comprehensive resource covers everything from initial calculations to real-life considerations, helping you harness the full potential of supercapacitors in your designs.