supercapacitor

55 Articles

Building A Spot Welder From 500 Junk Capacitors

August 20, 2022 by 5 Comments

[Kasyan TV] over on YouTube was given a pile of spare parts in reasonably large quantities, some of which were useful and allocated to specific projects, but given the given the kind of electronics they’re interested in, they couldn’t find a use for a bag of 500 or so low specification 470uF capacitors. These were not low ESR types, nor high capacitance, so unsuitable for power supply use individually. But, what about stacking them all in parallel? (video, embedded below) After a few quick calculations [Kasyan] determined that the total capacitance of all 500 should be around 0.23 Farads with an ESR of around 0.4 to 0.5 mΩ at 16V and packing a theoretical energy total of about 30 joules. That is enough to pack a punch in the right situation.

A PCB was constructed to wire 168 of the little cans in parallel, with hefty wide traces, reinforced with multiple strands of 1.8mm diameter copper wire and a big thick layer of solder over the top. Three such PCBs were wired in parallel with the same copper wire, in order to keep the total resistance as low as possible. Such a thing has a few practical uses, since the super low measured ESR of 0.6mΩ and large capacitance makes it ideal for smoothing power supplies in many applications, but could it be used to make a spot welder? Well, yes and no. When combined with one of the those cheap Chinese ‘spot welder’ controllers, it does indeed produce some welds on a LiPo cell with a thin nickel plated battery strip, but blows straight through it with little penetration. [Kasyan] found that the capacitor bank could be used in parallel with a decent LiPo cell giving a potentially ideal combination — a huge initial punch from the capacitors to blow through the strip and get the weld started and the LiPo following through with a lower (but still huge) current for a little longer to assist with the penetration into the battery terminal, finishing off the weld.

[Kaysan] goes into some measurements of the peak current delivery and the profile thereof, showing that even a pile of pretty mundane parts can, with a little care, be turned into something useful. How does such an assembly compare with a single supercapacitor? We talked about supercaps and LiPo batteries a little while ago, which was an interesting discussion, and in case you’re still interested, graphene-based hybrid supercapacitors are a thing too!

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Laser-Induced Graphene Supercapacitors From Kapton Tape

November 11, 2020 by 47 Comments

From the sound of reports in the press, graphene is the miracle material that will cure all the world’s ills. It’ll make batteries better, supercharge solar panels, and revolutionize medicine. While a lot of applications for the carbon monolayer are actually out in the market already, there’s still a long way to go before the stuff is in everything, partly because graphene can be very difficult to make.

It doesn’t necessarily have to be so hard, though, as [Zachary Tong] shows us with his laser-induced graphene supercapacitors. His production method couldn’t be simpler, and chances are good you’ve got everything you need to replicate the method in your shop right now. All it takes is a 405-nm laser, a 3D-printer or CNC router, and a roll of Kapton tape. As [Zach] explains, the laser energy converts the polyimide film used as the base material of Kapton into a sort of graphene foam. This foam doesn’t have all the usual properties of monolayer graphene, but it has interesting properties of its own, like extremely high surface area and moderate conductivity.

To make his supercaps, [Zach] stuck some Kapton tape to glass slides and etched a pattern into with the laser. His pattern has closely spaced interdigitated electrodes, which when covered with a weak sulfuric acid electrolyte shows remarkably high capacitance. He played with different patterns and configurations, including stacking tape up into layers, and came up with some pretty big capacitors. As a side project, he used the same method to produce a remarkable effective Kapton-tape heating element, which could have tons of applications.

Here’s hoping that [Zach]’s quick and easy graphene method inspires further experimentation. To get you started, check out our deep-dive into Kapton and how not every miracle material lives up to its promise.

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A Super UPS For The Pi

November 5, 2020 by 56 Comments

One of the problems with using a Raspberry Pi or most other systems in a production environment is dealing with sudden shutdowns due to power loss. Modern operating systems often keep data in memory that should be on disk, and a sudden power cycle can create problems. One answer is an uninterruptible power supply, but maintaining batteries is no fun. [Scott] wanted to do better, so he built a UPS using supercapacitors.

A supercapacitor UPS is nearly ideal. The caps charge quickly and don’t wear out as a battery does. The capacitors also don’t care if they stay in storage for a long time. The only real downside is they don’t have the capacity that batteries can have, but for a small computer like a Pi Zero it is pretty easy to gang up enough capacitors to do the job.

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Rapid Charging Supercapacitors

September 16, 2020 by 40 Comments

Battery technology is the talk of the town right now, as it’s the main bottleneck holding up progress on many facets of renewable energy. There are other technologies available for energy storage, though, and while they might seem like drop-in replacements for batteries they can have some peculiar behaviors. Supercapacitors, for example, have a completely different set of requirements for charging compared to batteries, and behave in peculiar ways compared to batteries.

This project from [sciencedude1990] shows off some of the quirks of supercapacitors by showing one method of rapidly charging one. One of the most critical differences between batteries and supercapacitors is that supercapacitors’ charge state can be easily related to voltage, and they will discharge effectively all the way to zero volts without damage. This behavior has to be accounted for in the charging circuit. The charging circuit here uses an ATtiny13A and a MP18021 half-bridge gate driver to charge the capacitor, and also is programmed in a way that allows for three steps for charging the capacitor. This helps mitigate the its peculiar behavior compared to a battery, and also allows the 450 farad capacitor to charge from 0.7V to 2.8V in about three minutes.

If you haven’t used a supercapacitor like this in place of a lithium battery, it’s definitely worth trying out in some situations. Capacitors tolerate temperature extremes better than batteries, and provided you have good DC regulation can often provide power more reliably than batteries in some situations. You can also combine supercapacitors with batteries to get the benefits of both types of energy storage devices.

Solar Satellite Glows At Night

August 30, 2020 by 16 Comments

They say that imitation is the sincerest form of flattery. If we were going to imitate one of master circuit sculptor Mohite Bhoite’s creations, we’d probably pick the little blinky solar satellite as a jumping off point just like [richardsappia] did. It’s cute, it’s functional, and it involves solar power and supercapacitors. What more could you want?

SATtiny is a pummer, which is BEAM robotics speak for a bot that soaks up the sun all day and blinks (or ‘pumms’, we suppose) for as long as it can throughout the night on the juice it collected. This one uses four mini solar panels to charge up a 4 F supercapacitor.

At the controls is an ATtiny25V, which checks every eight seconds to see if the supercapacitor is charging or not as long as there is enough light. Once night has fallen, the two red LEDs will pumm like a pair of chums until the power runs out. Check out the brief demo after the break.

Would you rather have something more nightstand-friendly? Here’s a mini night light sculpture with a friendly glow. If you haven’t started your entry into our Circuit Sculpture Challenge, there’s still plenty of time — the contest runs until November 10th.

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Modified Bricks Can House Energy, Too

August 16, 2020 by 43 Comments

What if building an emergency battery were as easy as painting conductive plastic onto bricks, stacking them, and charging them up? Researchers at Washington University in St. Louis have done just that — they’ve created supercapacitors by modifying regular old red bricks from various big-box hardware stores.

The bricks are coated in poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), a conductive polymer that soaks readily into the bricks’ porous surface. When the coated brick is connected to a power source such as a solar panel, the polymer soaks up ions like a sponge. PEDOT:PSS reacts with the iron oxide in the bricks, the rust that gives them their reddish-orange color. Check out the demonstration after the break — it’s a time lapse that shows three PEDOT-coated bricks powering a white LED for ten minutes.

We envision a future where a brick house could double as a battery backup when the power goes out. The researchers thought of that too, or at least had their eye on the outdoors. They waterproofed the PEDOT-coated bricks in epoxy and found they retain 90% of their capacitance and are still efficient after 10,000 charge-discharge cycles. Since this doesn’t take any special kind of brick, it seems to us that any sufficiently porous material would work as long as iron oxide is also present for the reaction. What do you think?

If you can get your hands on the stuff, PEDOT:PSS has all kinds of uses from paper-thin conductors to homebrew organic LEDs.

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Ultracapacitors Might Have Bad Fruity Smell

July 29, 2020 by 21 Comments

You might think the smell of an electrolytic capacitor boiling out is bad, but if scientists from the University of Sydney have their way, that might be nothing. They’ve devised an ultracapacitor — that uses biomass from the stinky durian fruit along with jackfruit. We assume the capacitors don’t stink in normal use, but we wouldn’t want to overload one and let the smoke out.

One of the things we found interesting about this is that the process seemed like something you might be able to reproduce in a garage. Sure, there were a few exotic steps like using a vacuum oven and a furnace with nitrogen, and you’d need some ability to handle chemicals like vinylidene fluoride. However, the hacker community has found ways to create lots of things with common tools, and we would imagine creating aerogels from some fruit ought not be out of reach.

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