EDLC Supercaps vs. Batteries: Power Storage for Your System

A question we occasionally get here at Digi-Key is how to employ EDLC supercapacitors as power storage devices, often for the goal of eliminating lead-acid or lithium ion batteries in a power circuit. While EDLCs are a very useful device with a lot of potential for enhancing your project’s power system, the short answer is that no EDLC can replace a battery.

Supercapacitors have the ability to charge and discharge very quickly, providing immediate power when it’s most needed, and as such they excel in catching momentary power dips or helping with moments of unusually high circuit load. They can provide power on demand and help eliminate moments of power deficiency in your circuit.

What they do not do well is long-term power storage. Supercapacitors typically have a very low operating voltage, usually in the vicinity of 2.5V. To gain a useful output rating, such as a typical 12V circuit, several EDLCs must be used in series, which necessitates voltage balancing circuitry to prevent the overvoltage and destruction of any one EDLC, as well as slashing the capacitance value of any given EDLC cell. Because EDLCs, like any other capacitors, are purely electrostatic devices with no chemical component, EDLCs are very expensive on a per-watt basis and cannot store energy economically for much longer than a minute.

EDLCs can help regulate the power coming from your DC battery system and ease the strain on the battery during peak usage, increasing the overall service life of your power system. Sadly, they cannot replace that entire power system for you

For more information, check out this handy resource, What’s the Role of the Supercapacitor, from Battery University.