Instructable user [EngineeringShock] got sick of buying batteries for his devices all the time and has instead opted to build himself a super capacitor bank that can be used to power common household items.
His “forever” rechargeable capacitor bank is made of two large super capacitors rated at 400 farads apiece. It is charged through a LM317-based charging circuit that is adjustable to allow for slow or fast charging, the latter of which he admits, is slightly dangerous.
Since the super caps are only rated at 2.7 volts, they are wired through a DC-DC booster circuit that allows him to adjust the output voltage from 4.3 v to 34 v. The adjusted voltage is then passed through a digital display that allows him to see what the output voltage is at any time.
He says that the super cap bank can power his computer’s speakers for about two hours before requiring a recharge, which takes just a few short minutes, depending on how he is charging them.
While it’s not exactly cheap, the capacitor bank could be useful for those requiring quick portable power for relatively short periods of time. If we were to build one ourselves, we would likely fit all of the components into a small project box to protect the caps from accidental discharging, and top it off with a couple of solar cells to charge it for free during the day.
Keep reading to see a quick video demonstration of his super cap “battery” in action.