Kites Fill Electricity Generation Gaps

January 22, 2024 by Bryan Cockfield 48 Comments

Looking at a wind turbine from first principles, it’s essentially a set of wings that generate lift in much the same way an airplane wing does. Putting the wings on a rotor and calling them “blades” is not a huge step away from that. But there’s no reason the wing has to rotate, or for that matter be attached to a fixed platform, in order to generate electricity. Anything that generates lift can be used, and this company is demonstrating that with their kite-powered wind generators.

Like other wind energy producers that have used kites to generate electricity, this one is similar in that the kite is flown in a figure-8 pattern downwind where it can harness energy the most efficiently, pulling out a tether which is tied to a generator. When fully extended, it is flown to a position where the wind doesn’t strike the kite as strongly and the tether is reeled in. Unlike other kite generators we’ve seen, though, this one is offered as a turnkey system complete with battery backup and housed in a self-contained shipping unit, allowing it to be deployed quickly to be used in situations where something like a diesel generator would be impossible to get or where the fuel can’t be obtained.

The company, called Kitepower, does note that these aren’t replacements for traditional wind turbines and would be used more for supporting microgrids. There are still some advantages to using kites over fixed turbine blades though: kites can reach higher altitude where the wind is stronger, and they require less materials for a given amount of energy production, often making them even more environmentally friendly and possibly more economical as well. Surprisingly enough, kites can also be used to generate energy even in places where there’s no wind at all.

Arduino Measures Remaining Battery Power With Zero Components, No I/O Pin

December 21, 2023 by Donald Papp 22 Comments

[Trent M. Wyatt]’s CPUVolt library provides a fast way to measure voltage using no external components, and no I/O pin. It only applies to certain microcontrollers, but he provides example Arduino code showing how handy this can be for battery-powered projects.

The usual way to measure VCC is simple, but has shortcomings.

The classical way to measure a system’s voltage is to connect one of your MCU’s ADC pins to a voltage divider made from a couple resistors. A simple calculation yields a reading of the system’s voltage, but this approach has two disadvantages: one is that it constantly consumes power, and the other is that it ties up a pin that you might want to use for something else.

There are ways to mitigate these issues, but it would be best to avoid them entirely. Microchip application note 2447 describes a method of doing exactly that, and that’s precisely what [Trent]’s Arduino library implements.

What happens in this method is one selects Vbg (a fixed internal voltage reference that is temperature-independent) as Vin, and selects Vcc as the ADC’s voltage reference. This is essentially backwards from how the ADC is normally used, but it requires no external hookup and is only a bit of calculation away from determining Vcc in millivolts. There is some non-linearity in the results, but for the purposes of measuring battery power in a system or deciding when to send a “low battery” signal, it’s an attractive solution.

Being an Arduino library, CPUVolt makes this idea very easy to use, but the concept and method is actually something we have seen before. If you’re interested in the low-level details, then check out our earlier coverage which goes into some detail on exactly what is going on, using an ATtiny84.

Old Prius Gets Upgraded Batteries

December 18, 2023 by Bryan Cockfield 24 Comments

So many of the batteries made today are lithium batteries of some sort, from mobile phones, laptops, and drones to electric cars and grid storage solutions. But this technology is relatively new; even as late as the 90s and early 00s the only widely-available batteries for things like power tools or the new hybrid vehicles coming on the market were nickel-metal hydride (NiMH). While it was good for the time, they don’t hold up to all of the advantages lithium has. There’s still plenty of hybrid vehicles on the road using these batteries, so if you’re driving an older Prius and want to give it a modern refresh, there’s a quick option to swap your old batteries.

Despite lithium technology being available for several decades, the switch to lithium for the Toyota Prius wasn’t instant, with many variants still using NiMH batteries as late as the 2020s largely because the NiMH batteries are less expensive and less maintenance-intensive than lithium batteries are. As these batteries lose capacity, the cars are still driveable but the advantages of the hybrid drivetrain won’t be as accessible anymore. The upgrade, from a company called Project Lithium, replaces these batteries with modern lithium technology that can improve the efficiency and performance of these cars even above their original capabilities since lithium batteries have more power density.

With the Toyota Prius being among the most reliable vehicles on the road thanks to the electric motor in the hybrid drivetrain taking a lot of stress off of the internal combustion engine, it’s often worth upgrading these old batteries to modern ones to squeeze every last mile from these workhorses as possible. With many of the replacement processes being almost as simple as lifting out an old battery and placing a new one in, it can be a no-brainer if that’s the only issue with the vehicle otherwise. This is also true of all-electric vehicles as well, although the process to replace the battery can be a little more involved.

Thanks to [JohnU] for the tip!

Mods Turn Junk UPS Into A Long-Endurance Beast

December 15, 2023 by Dan Maloney 36 Comments

If you’ve got a so-called uninterruptible power supply (UPS) on your system, you’re probably painfully aware that the “uninterruptible” part has some pretty serious limits. Most consumer units are designed to provide power during a black out only long enough to gracefully shut down your system. But with a few hacks like these, you can stretch that time out and turn it into a long-endurance UPS.

As many good stories do, this one starts in the trash, where [MetaphysicalEngineer] spotted an APC home office-style UPS. It was clearly labeled “broken,” but that just turned out to be a dead battery. While he could have simply replaced it with a 12-volt sealed lead-acid battery, [Meta] knew that his computer setup would quickly deplete the standard battery. A little testing showed him that a car battery would extend the run time significantly, especially if he threw in some extra cooling for the onboard inverter.

His final design uses a marine deep-cycle battery in a plastic battery box with the UPS mounted on top. The vacated battery compartment made a great place to add a cooling fan, along with a clever circuit to turn it on only when the beeper on the UPS sounds, with a bonus volume control for the annoying sound. He also added accessories to the battery box top, including a voltmeter, a USB charger, and a switched 12-volt power outlet. And kudos for the liberal use of fuses in the build; things could get spicy otherwise. The video below shows the entire build along with all the testing. [MetaphysicalEngineer] managed to triple the estimated runtime for the load he’s trying to power, so it seems like a win to us.

If your needs run more toward keeping your networking gear running through a blackout, you might want to check out this inverter-less DC UPS.

Continue reading “Mods Turn Junk UPS Into A Long-Endurance Beast” →

Rock Salt May Lead The Way To Better Batteries

October 5, 2023 by Jenny List 58 Comments

The regular refrain here when it comes to announcements of new battery chemistries hailed as potentially miraculous is that if we had a pound, dollar, or Euro for each one we’ve heard, by now we’d be millionaires. But still they keep coming, and it’s inevitable that there will one or two that break through the practicality barrier and really do deliver on their promise. Which brings us tot he story which has come our way today, the suggestion that something as simple as rock salt could triple the energy density of a lithium-ion vehicle battery.

The research led from Lawrence Berkeley National Laboratory started around the use of cobalt in the battery cathode, an expensive and finite resource with the added concern of being in large part a conflict mineral from the Democratic Republic of Congo. Cobalt is used in the cathodes because its oxide crystals form a stable layered structure into which the lithium ions can percolate. Alternative layered-structure metal oxides perform less well in retaining the lithium ions, making them unsuccessful substitutes. It seems that the three-dimensional structure of a rock salt crystal performs up to three times better than any layered oxide, which is where the excitement comes from.

Of course, if it were that simple we’d all be using three-times-more-powerful, half-price 18650s right now, which of course we aren’t. The challenge comes in making a rock salt cathode which both holds the lithium ions, and keeps that property reliably over the thousands of charge cycles needed for a real-world application. This one may yet be anther dollar on that metaphorical pile, but it just might give us the batteries we’ve been looking for.

Then again, when you’re looking at exciting battery chemistry, why limit yourself to lithium?

Will Nickel-Hydrogen Cells Be The Energy Storage Holy Grail?

September 27, 2023 by Jenny List 38 Comments

You may have heard us here remarking in the past, that if we had a pound, dollar, or Euro for every miracle battery technology story we heard that was going to change the world, we would surely be very wealthy by now. It’s certainly been the case that many such pronouncements refer to promising chemistries that turn out only to be realizable in a lab, but here there’s news of one with a bit of pedigree. Nickel hydrogen batteries have a long history of use in space, and there’s a startup producing them now for use on the ground. Could they deliver the energy storage Holy Grail?

The cathode in a nickel-hydrogen battery is formed by nickel hydroxide, and the anode is formed of hydrogen. If a gas as an anode sounds far fetched, we’re guessing that their structure is similar to the zinc-air battery, in which zinc hydroxide forms in a paste of powdered zinc, and works against oxygen from the air over a porous conductive support. What gives them their exciting potential is their ability to take more than 30,000 charge/discharge cycles, and their relative safety when compared to lithium ion cells. Hydrogen in a pressure vessel might not seem the safest of things to have around, but the chemistry is such that as the pressure increases it reacts to form water. The cost of the whole thing is reduced further as new catalysts have replaced the platinum used by NASA on spacecraft.

We really hope that these batteries will be a success, but as always we’ll wait and see before calling it. They may well be competing by then with the next generation of zinc-air cells.