What do you do when you find a small horde of supercapacitors? The correct answer is a spectrum of dangerous devices ranging from gauss guns to quarter shrinkers. [Rinoa] had a less destructive idea: she’s replaced the battery in a laptop with a bank of supercapacitors.
The supercaps in question are 2.7 Volt, 500 Farad caps arranged in banks six for a total of about 3 watt-hours in each bank. The laptop used for this experiment is an IBM Thinkpad from around 1998. The stock battery in this laptop is sufficiently less advanced than today’s laptop batteries. Instead of using a microcontroller and SMBus in the battery, the only connections between the battery and laptop are power, ground, and connections for a thermocouple. This is standard for laptops of the mid-90s, and common in low-end laptops of the early 2000s. It also makes hacking these batteries very easy as there’s no associated microprocessors to futz around with.
With all the capacitor banks charged, the laptop works. It should – there isn’t a lot of intelligence in this battery. With one bank of six supercaps, [Rinoa] is getting a few minutes of power on her laptop. With a stack of supercaps that take up about the same volume as this already think Thickpad, [Rinoa] can play a few turns of her favorite late-90s turn-based strategy game. It’s not much, but it does work.
The modern human’s worst nightmare: a power outage. Left without cat memes, Netflix, and — of course — Hackaday, there’s little to do except participate in the temporary anarchy that occurs when left without internet access. Lamenting over expensive and bulky uninterruptible power supplies, Youtube user [Gadget Addict] hacked together a UPS power bank that might just stave off the collapse of order in your household.
This simple and functional hack really amounts to snipping the end off of a USB power cable. The cable is then attached to a screw terminal to barrel connector adapter and plugged it into a pass-through power USB power bank. No, really — that’s all there is to it. [Gadget Addict] notes that while most modems and routers are designed to run off a 12V power supply, they still operate at 5V. He goes on to connect several router and router/modem combination units to the power bank. In each case the system appears to boot up and perform normally.
On occasion I have encountered portable soldering irons and my impressions of them have ranged from nearly usable to total rubbish. While using a popular butane powered model and pondering if it was really any better than a copper wire and a candle a thought occurred to me. A regular old Weller station runs on 24 volts AC and performs all of its temperature regulation in a magnetically activated thermostatic fashion and all of that goodness occurs within the hand piece itself. It stood to reason that it could perform just as well with a DC source.
In this instance we are ignoring the negative effects of switching DC current over AC current on mechanical contacts. After all we are “In the Trenches” wherever we might have need for such a device. Using a couple of gel cell 12 volt 7 amp hour batteries freshly removed from a UPS I strung them up, and there you have it, a totally battery operated iron with performance equal to that of the one at my bench.
Right at 24 volts the iron Thermocycles at the same rate as it would be while using the bench top supply for it. Just sitting under no load it cycles about every ten seconds and there was no perceptible difference in heat capacity or performance. A fully charged pair of batteries will last all day. The on state current draw from a full charge (13.5 volts on each of the batteries) yielded about a 2 amp draw. As the voltage began to decrease the current off cycle would get shorter as one would expect, but no drop in heat transfer was noticed until the batteries were well depleted and that took most of a work day.
For this instance I used the hand piece from the venerable Weller WTCPT station. For ongoing use I would not recommend this due to the use of a mechanical contact within the unit and switching of DC can reduced the life of most mechanical switches. Currently I am awaiting the arrival of some cheap eBay Hakko handpieces; I am sure they are knockoffs, but fine to experiment with a simple PWM with a feedback loop controller as the basic Hakko design also utilizes a 24 volt source. An automatic shut off timer would also be handy to avoid premature battery abuse due to a forgetful operator.
The uninterruptible power supply was once a standard fixture in the small office/home office as a hedge against losing work when the electrons stop flowing from your AC outlet. Somewhat in decline as computing hardware shifts away from dedicated PCs toward tablets, phones and laptops, the UPS still has a lot of SOHO utility, and off-the-shelf AC units are easy to find. But if your needs run more to keeping the electrons flowing in one direction, then you might want to look at [Kedar Nimbalkar]’s programmable DC backup power system.
Built inside a recycled ATX power supply case, [Kedar]’s project is heavy on off-the-shelf components, like a laptop power supply for juice, a buck converter to charge the 12 volt sealed lead acid battery, and a boost converter to raise the output to 19.6 volts. An Arduino and an optoisolator are in charge of controlling the charging cycle and switching the UPS from charging the battery to using it when mains voltage drops.
As versatile as the Raspberry Pi is, it has a weakness when it needs to be able to shut down properly during a power outage, especially when handling data-sensitive or industrial applications. To solve this problem, [Pavol Sedlacek] has created a supercapacitor-based UPS specifically for the Raspberry Pi that gives it enough time to properly halt its processes and shut down if it detects a power failure.
The device is called the Juice4Halt. It uses a DC-DC converter to provide power to the Pi from the normal power supply and to charge the supercapacitors during normal operation. It is bidirectional, so in the event of a power failure it works in reverse to take power from the capacitors and feed it back to the Pi. A second DC-DC converter handles power from an external power supply.
A side effect of using supercapacitors as a UPS is that they can also help the Pi survive brownouts. The project site has an incredible amount of detail about the functionality of the device, including circuit diagrams and the source code. We’ve seen other supercapacitor-based UPS units before but this particular one is much more robust and would be truly at home in any industrial or other sensitive setting.
What happens when you want to integrate a Raspberry Pi into some kind of project that gets turned on and off with mains voltage? Do you power the Pi separately, or make a UPS for it?
[Lutz Lisseck] decided he wanted to turn his ambient-lamp (Rundbuntplasma) on and off with only the main power switch in his Hackerpsace. He could build a traditional UPS using a battery pack (it’s only 5V after all!) but decided to take it a step further. He picked up a pair of 50F supercapacitors. This way his UPS would last longer than his Pi would! The caps store just enough power that when the main supply is cut, a GPIO notices, tells the Pi, and it begins a shutdown sequence lasting about 30 seconds.
While [Lutz] is using two 2.7V supercapacitors, he mentions it would be a lot cheaper to use a step-up converter instead of putting them in series — but he had the caps on hand so decided to use both.
Looking at this huge Uninterruptible Power Supply we are a little envious. It’s meant to hang on the wall of a utility room and power your critical devices. [Radek Hvizdos] has had it in service for quite some time, and when he started thinking of replacing the internal battery he decided to see if he could also extend the functionality. To do so he needed to get at the firmware of the chip controlling the device. And so began his adventure of dumping the firmware from the read-protected PIC 18F452.
The challenge of dumping code from a write-protected chip is in itself a fun project. But [Radek] was actually interested in fixing bugs and adding features. The wishlist feature we’d be most interested in is a kind of triage for shutting down devices as the internal battery starts to run low. Nice! But starting from scratch with the firmware is a no-go. You can see the two places where he connected to the PCB. The upper is for using a PIC programmer. The lower is an I2C connection used to dump the EEPROM with an improvised Bus Pirate.
In the end it was improper lock bit settings that opened the door to grabbing the firmware. The bootloader section of the PIC is not locked, and neither is the ability to read from FLASH at run-time. These two combined allowed him to write his own code which, when flashed to the bootloader section, dumps the rest of the firmware so that it may be combined into a complete file afterward. Since posting this fascinating article he has made a follow-up about disassembling the code.