How Do Super Capacitors Work?

What Is a Super Capacitor?

Those of you familiar with the Back to the Future franchise know that the (fictional) flux capacitor is a critical component of the famous DeLorean time machine, enabling time travel through its mysterious sci-fi capabilities. Its hypothetical cousin, the supercapacitor, may not be as well-known among the general public, but it’s much more influential in our daily lives. And in certain industrial settings, it could save you a ton of money.

Let’s dig in.

Capacitors and Super Capacitors: The Basics

Capacitors are a central component in circuits around the world, functioning as passive components like inductors and resistors. These crucial components store energy in the form of an electric field – almost like a battery. But unlike a battery, capacitors are fundamentally limited in how much energy they can store.

A supercapacitor is, as the name suggests, an upgraded version of a capacitor – one with very high capacitance. Capacitance, if you aren’t familiar, is a measurement of the capacitor’s total charge as compared to its voltage (measured in farads).

Unlike traditional capacitors, supercapacitors can be recharged – and for the most part, can be used like batteries. With $100 of circuitry or less, you could hypothetically create a supercapacitor capable of lasting many years. Think of it as functionally similar to, yet mechanically distinct from, a battery.

Pros and Cons of Super Capacitors

Why would you consider using a supercapacitor instead of a battery?

Let’s take a look at the advantages:

· Lifespan and cycle duration

All rechargeable batteries have a finite lifespan; after a certain number of cycles of charging and discharging, they won’t be able to hold a charge any longer. Supercapacitors can go through 500,000 to 1,000,000 of these cycles (assuming you use them responsibly), making them much longer lasting.

· Superior shelf life

Ignoring the charging cycle for a moment, batteries also have a limited shelf life. If you charge a battery, set it aside for a few months, then try to use it again, you’ll be disappointed to find that the battery is dead. Supercapacitors also have a limited shelf life, but it’s much, much more forgiving. Even if you buy cheap supercapacitors and use them carelessly, they can last on the shelf for several years. Top brands, when used ideally, can last 60 years or longer. That’s right – your supercapacitor might just outlive you.

· Mitigated battery “memory loss”

Traditional batteries suffer from a problem called “memory loss.” If you overcharge these batteries by leaving them in a charger, you can compromise the unit’s ability to hold a charge. Do this enough times and the battery will eventually die. Supercapacitors don’t have this problem; they automatically stop accepting new energy once full.

· Faster charging speed

The equivalent series resistance (ESR) of supercapacitors is very low when compared to traditional batteries – sometimes 5 percent or less of the ESR of typical commercial batteries. What does that mean for you? Basically, if you have the right charging equipment, you should be able to charge a supercapacitor in just a few seconds.

· Environmental friendliness

One of the main problems with lithium-ion batteries is their tendency to release harmful chemical gasses and, if improperly disposed of, leach chemicals into the soil. When using these batteries at scale, operators are often forced to make accommodations for these gasses – like increasing ventilation and, in some cases, wearing special protective equipment. By comparison, supercapacitors are much more environmentally friendly; you can store them and use them without risking any harm to the people around you or the environment.

· Lower risk of explosions

In line with this, most people know that traditional batteries carry a small explosive risk; if a battery short circuits, it can overheat and eventually explode into flames. If a supercapacitor experiences a direct short circuit, it will heat up – but never explode.

Does that mean supercapacitors are the perfect choice for every situation?

Not quite. There are also some disadvantages to keep in mind:

· Mass and storage space

Supercapacitors can be up to 10 times bigger than conventional batteries, making them harder to transport and store in some situations.

· Lower maximum voltage

The maximum voltage rating of a supercapacitor is lower than its battery counterpart. Most people solve this issue by using many supercapacitors together in a series (though this comes with the downside of lowering capacitance).

· Overheating risk

Explosions aren’t a concern, but a short circuit can cause overheating.

super capacitor overheating risk

· Price

Supercapacitors are typically more expensive than batteries, though you can find good deals if you know where to look.

Supercapacitors live up to their impressive-sounding name, offering many advantages over traditional batteries. The question is, do you want to shop around for the best deal on supercapacitors? Or try your hand at making one of your own? 

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