Hackaday Prize Entry: Self Sustained Low Power Nodes

Consider for a second the Internet of Things. A vast network of connected devices, programmable matter, and wearable electronics can only mean one thing: there’s going to be a ton of batteries. While changing the battery in a smoke detector may seem tolerable, changing the batteries in a thousand sensor nodes is untenable. The solution to this problem is self-contained sensor nodes, and right now the best power source for mobile devices is probably solar.

For his Hackaday Prize entry, [Shantam Raj] is building a self-contained sensor node. It’s a Bluetooth device for the Internet side of this Thing, but the real trick to this device is solar energy harvesting and low power capabilities through optimized firmware.

Basically, this system is a low-power SoC with Bluetooth. The power from this device comes from a small solar cell coupled with a very efficient power supply and some new, interesting supercapacitors from Murata. These supercaps are extremely small, have high storage capacity, low ESR, and fast charging and discharging. The test board (seen in the video below) provides a proof of concept, but this device has a problem: there’s a single ‘sanity check’/power LED on the board that consumes 4 mA. The microcontroller, when running the optimized firmware, only consumes 1 mA. Yes, the LED thrown into the prototype that only serves as an indication the device is on is the biggest power sink in the entire system.

This project is great, and it’s exactly what we’re looking for in The Hackaday Prize. If the Internet of Things ever happens as it was envisioned, we’re going to be buried under a mountain of coin cell lithium batteries. Some sort of energy harvesting scheme is the only way around this, and we’re happy to see someone is working on the problem.

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WISP Needs No Battery Or Cable

One of the problems with the Internet of Things, or any embedded device, is how to get power. Batteries are better than ever and circuits are low power. But you still have to eventually replace or recharge a battery. Not everything can plug into a wall, and fuel cells need consumables.

University of Washington researchers are turning to a harvesting approach. Their open source WISP board has a sensor and a CPU that draws power from an RFID reader. To save power during communication, the device backscatters incoming radio waves, which means it doesn’t consume a lot of its own power during transmissions.

The big  news is that TU Delft has contributed code to allow WISP to reprogram wirelessly. You can see a video about the innovation below. The source code is on GitHub. Previously, a WISP had to connect to a PC to receive a new software load.

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I am a Battery: Harvesting Heat Energy

If you get tired of charging batteries, you might be interested in [Hackarobot’s] energy harvesting demo. He uses a peltier device (although he’s really using it as a thermocouple which it is). A 1 farad super capacitor stores energy and an LTC3108 ultra low voltage converter with a 1:100 ratio transformer handles the conversion to a useful voltage.

The truth is, the amount of energy harvested is probably pretty small–he didn’t really characterize it other than to light an LED. In addition, we wondered if a proper thermocouple would work better (some old Russian radios used thermocouples either in fireplaces or kerosene lamps to avoid requiring batteries). Although a Peltier device and a thermocouple both use the Seebeck effect, they are optimized for different purposes. Thermocouples generate voltage from a temperature differential and Peltier modules generate temperature differentials from voltage.

However, as [Hackarobot] points out, the same technique might be useful with other alternate power sources like solar cells or other small generators. The module used has selectable output voltages ranging from 2.35V to 5V.

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Self Powered Camera Powers Itself

Cameras sense light to create images, and solar cells turn light into energy. Why not mash the two together and create a self-powered camera?

The Computer Vision Laboratory at Columbia built this unique camera, which harvests power from its photodiode sensors. These photodiodes also act as an array of pixels that can recover an image. The result is a black and white video camera that needs no external power supply.

The energy harvester circuit charges up a supercap that provides power to the system. The frame rate of the camera is limited by the energy that can be harvested: higher frame rates require more juice. For this reason, the team developed an algorithm that varies the frame rate based on available energy.

The MC13226V microcontroller that was used for this build features an internal 2.4 GHz radio. The group mentions wireless functionality as a possibility feature in the future, which would make for a completely untethered, battery free camera.

The iFind Kickstarter Campaign Was Just Suspended

A little more than one month ago we featured a Kickstarter campaign that was raising quite a lot of eyebrows and over half a million dollars. This particular product was a battery-free tag meant to be attached to anything you may lose in your daily life. It was supposed to communicate with Bluetooth Low Energy (BLE) devices and have a 200ft (60m) detection range.

The main claim was that the iFind could harvest enough power from existing RF fields inside a typical home environment to operate for centuries. As Kickstarter just cancelled its funding a few minutes ago it seems that the basic maths Hackaday did a while ago were correct and that the project was in fact a scam. We’ll direct our readers to this particular comment that sums up all the elements pointing to a fraudulent campaign and show you the email that the backers received:

A review of the project uncovered evidence of one or more violations of Kickstarter’s rules, which include:

  • A related party posing as an independent, supportive party in project comments or elsewhere
  • Misrepresenting support by pledging to your own project
  • Misrepresenting or failing to disclose relevant facts about the project or its creator
  • Providing inaccurate or incomplete user information to Kickstarter or one of our partners

Putting aside this news, this campaign’s cancellation raises a bigger question: why didn’t it happen before and how could we control Kickstarter campaigns? On a side note, it’s still very interesting to notice the nearly religious fervor of the sunk cost fallacy that such campaigns create in their comments.

Thanks [Rick] for the tip!

Energy Harvesting Peltier Ring

[Sean] is by no means an electrical engineer, but when he discovered the magic of Peltier plates he knew he had to make a project with them. This is his Energy Harvesting Peltier Ring.

The effect he is harnessing is called the SeeBeck Effect — the process of generating electricity through temperature differentials. He has shown how peltier plates work to many people, and, as you can guess, most people think they are amazing (free energy wow!). Unfortunately, most peltier plates are rather large and bulky, so [Sean] decided he wanted to try to design something small enough that could fit on a ring. Just a proof of concept, to light a tiny SMD LED.

The tiny Peltier plate he found generates about 0.3V with a temperature differential of about 20C — not bad, but it won’t light up any standard LEDs at that voltage! He started looking into voltage steppers and discovered Linear Technology’s 3108 Ultralow Voltage Step-up converter and Power Manager — a surface mount chip capable of scaling 0.3V to 5V. The only problem? [Sean’s] never done surface mount soldering.

His first circuit was built on a prototyping board, and after it worked successfully, he designed a PCB using Fritzing. Another success! Prototyping complete, it was now time to try to downsize the PCB even more to fit on a ring. Realizing there was no way he was going to fit it on a single ring, he decided to make a double ring out of CNC machined aluminum. He made use of his school’s CNC shop and the ring came out great. It works too! The room has to be fairly cool for the LED to light, but [Sean] definitely proved his concept. Now to make it even smaller!

Energy harvesting to build a Carbon Monoxide Detector with no battery


There are a few devices that work tirelessly to protect our lives. We’re talking about smoke detectors and carbon monoxide detectors. Increasingly these either need to be hardwired into the home, or have a sealed battery which is good for ten years (in the case of smoke detectors). [Gelmi] recently had to change the battery in his Carbon Monoxide detector — which happens very rarely — and he it got him to thinking. If the batteries need to be changed so rarely, how hard would it be to harvest energy to power the device?

Our first thought was that he’d use inductance like those spy birds which perch on power lines. But instead he went for the heat lost from using the hot water spigot. Above you can see his test rig which attached a Peltier device to the faucet in his bathroom. Whenever you turn on the hot water the faucet also heats up. The differential between faucet temperature and ambient room temperature generates a small amount of power. This is a suitable source, but only if he could also cut the amount of power needed by the detector. This adventure takes him down the rabbit hole, learning about how the sensors work and designing for reliability at the lowest consumption level possible.

The faucet application might seem peculiar. But if you use a natural gas water heater you want a carbon monoxide detector near it. Attach the Peltier to the outflow and every time any hot water tap in the house is opened your system will get a bit of a recharge.

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