Supercapacitor-Powered Speaker Charges in Seconds

While learning the basics of electronics, you'll often hear capacitors described as being "kind of like batteries." That's because they store electricity. But they aren't often used like batteries and are instead integrated into circuits to perform functions like smoothing out power delivery to other components. Supercapacitors, on the other hand, can perform like batteries and offer some tremendous benefits, such as extremely fast charging. JGJMatt took advantage of that capability to build this supercapacitor-powered speaker that charges in just seconds.

Supercapacitors offer two massive advantages over your typical lithium batteries. First, they can withstand hundreds of thousands — or even millions — of charge/discharge cycles without degradation. Compare that to hundreds of cycles before a lithium battery starts degrading. Second, they can charge and discharge extremely quickly. A lithium battery may take a couple of hours to charge, while an equivalent supercapacitor may do the same in under a minute.

The major disadvantage of supercapacitors is their high self-discharge rate, which means that they'll lose all of their energy in short order, even if the devices they power are off. In one month, a supercapacitor will self-discharge about 30% of its energy, while a lithium battery will only lose about 10%. That makes a supercapacitor a poor choice for long-term energy storage.

In this case, JGJMatt didn't need long-term storage; he only needed to power his speaker once a day for a four-hour period while South Africa performs loadshedding to lighten the load on power infrastructure. His supercapacitor-powered speaker lasts at least six hours and will recharge in seconds once the mains power comes back on, making it perfect for that situation.

JGJMatt's custom PCB for this device contains two 400-Farad supercapacitors wired in series. Voltage output of supercapacitors decreases as their energy depletes, so the PCB has a boost converter to produce a stable voltage. That powers a class-D amplifier, which pumps up the audio signal from a USB-C analog source (a smartphone or PC). Optionally, a Bluetooth module enables wireless connections. An integrated solar panel keeps the supercapacitors topped off, allowing for continuous music playback if there is enough sunlight available.

All of those components fit into an attractive 3D-printed enclosure that would make Dieter Rams smile. But beyond good looks, we think this is a very useful device. Many people would gladly trade long-term storage for fast-charging when it comes to devices they use frequently and this speaker makes the benefits obvious.