inverter

60 Articles

The Trashiest Of Mains Inverters

August 31, 2024 by 21 Comments

Switch-mode technology has made inverters which take a low DC voltage and turn it into a usable mains voltage within the reach of everybody. But still, there might be moments when a mains supply is needed and you’re not lucky enough to have AliExpress at your fingertips, and for that, here’s [Rulof] with a mains inverter that is simultaneously awful and awesome. He’s made a rotary converter, from trash and off the shelf parts.

While a switch-mode converter operates using PWM at many times the output frequency for efficiency, we’re guessing that most readers will be familiar enough with how AC works to see how a low frequency converter turns DC into AC. A set of switches repeatedly flip the polarity, and the resulting square wave is fed into a transformer to step up to the final voltage. The switches can be mechanical as with old-style converters that used vibrating reeds or rotary armatures, or they can be electronic using power transistors. In this case they are a set of microswitches actuated by a set of cams on a shaft driven by a small motor, and the transformer comes from a surplus UPS.

We’re guessing that the frequency will be only a few Hz and the microswitches will suffer from switching such an inductive load, but as you can see in the video below the break it does light a mains bulb, and we’re guessing it would be enough to activate most wall-wart switching power supplies. We’re not so sure though about his use of the IEC sockets from the UPS to carry 12 volts, as the current may be a little much for them.

Meanwhile if you thirst for more of this kind of thing, we have you covered.

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A man's hand with a black ring touches a white box. It is square on the bottom and has a sloped top. Various AC, 12V, and USB ports adorn its surface. It's approximately the size of a human head.

DIY Off Grid Battery Pack From EV Battery

July 31, 2024 by 15 Comments

Car camping gets you out in the great outdoors, but sometimes it’s nice to bring a few comforts from home. [Ed’s Garage] has taken a module from a salvaged EV and turned it into a handy portable power station.

With 2.3 kWh of storage from the single Spark EV module, the battery pack can power [Ed]’s hotplate, lights, fridge, and other electric accessories while camping away from shore power. The inverter he selected can provide up to 1500W of AC power and his 12V converter can do 150W. Several USB ports and a wireless charging pad adorn the outside next to the waterproof AC ports. He even printed a small magnetic flashlight to reuse the light from the inverter which uses an 18650 cell that can be charged from the big battery in a charger built into the exterior of the pack.

The battery management system (BMS) has a Bluetooth module allowing for remote monitoring of state of charge and setting the maximum and minimum charge points for the pack. The whole thing comes in at 73 pounds (33 kg), and while he had originally thought to give it wheels to roll, he changed his mind once he thought more about what sort of wheels he’d need to maneuver the thing in the backcountry.

If you’re thinking of building your own power pack, why not checkout a few other builds for inspiration like this one from tool batteries or one designed to charge directly from a solar panel. Be sure you checkout our guide on how to select a BMS if you’re going to use a lithium-based chemistry.

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Robotic Platform Turns Shop Vac Into Roomba

May 8, 2024 by 14 Comments

The robotic revolution is currently happening, although for the time being it seems as though most of the robots are still being generally helpful to humanity, whether that help is on an assembly line, help growing food, or help transporting us from place to place. They’ve even showed up in our homes, although it’s not quite the Jetsons-like future yet as they mostly help do cleaning tasks. There are companies that will sell things like robotic vacuum cleaners but [Clay Builds] wanted one of his own so he converted a shop vac instead.

The shop vac sits in a laser-cut plywood frame and rolls on an axle powered by windshield wiper motors. Power is provided from a questionable e-bike battery which drives the motors and control electronics. A beefy inverter is also added to power the four horsepower vacuum cleaner motor. The robot has the ability to sense collisions with walls and other obstacles, and changes its path in a semi-random way in order to provide the most amount of cleaning coverage for whatever floor it happens to be rolling on.

There are a few things keeping this build from replacing anyone’s Roomba, though. Due to the less-than-reputable battery, [Clay Builds] doesn’t want to leave the robot unattended and this turned out to be a good practice when he found another part of the build, a set of power resistors meant to limit current going to the vacuum, starting to smoke and melt some of the project enclosure. We can always think of more dangerous tools to attach a robotic platform to, though.

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Power Tool Packs Make A Portable Powerhouse

February 21, 2024 by 15 Comments

The revolution in portable and cordless appliances has meant that we now own far fewer mains-powered gadgets than we might once have done, but it hasn’t entirely banished the old AC outlet from our lives. Particularly when away from a mains supply it can be especially annoying, but now instead of a generator there’s the option of an inverter. [Thijs Koppen] has made a very neat all-in-one mains power station in a plastic flight case using the ubiquitous and handy standardized Makita power tool packs.

From one perspective this is a simple enough build, because wiring a battery to an inverter isn’t the most difficult of tasks. But he’s designed his own 3D printed Makita battery receptacles which should be of interest to plenty of readers, and with three packs in series he’s sourced an unusual 72 volt inverter to supply mains. The photo of him charging a Tesla with the result is probably more for show than practicality though.

We’ve featured quite a lot of cordless tool battery hacks over the years as their ready availability and quick interchangeability is attractive. If you ever fancy engineering your own mounting, we’ve taken a look at someone doing just that.

Sun On The Run: Diving Into Solar With A Mobile PV System

January 17, 2024 by 36 Comments

For obvious reasons, there has been a lot of interest in small-scale residential solar power systems lately. Even in my neck of the woods, where the sun doesn’t shine much from October to April, solar arrays are sprouting up on rooftops in a lot of local neighborhoods. And it’s not just here in suburbia; drive a little way out into the country or spend some time looking around in Google maps and it won’t take long to spy a sizable array of PV panels sitting in a field next to someone’s ranch house or barn.

Solar has gotten to the point where the expense of an installation is no longer a serious barrier to entry, at least if you’re willing to put in a little sweat equity and not farm the project out to a contractor. Doing it yourself requires some specialized tools and knowledge, though, over and above your standard suite of DIY skills. So, in the spirit of sharing hard-won knowledge, I decided to take the somewhat unusual step of writing up one of my personal projects, which has been in progress for a couple of years now and resulted in a solar power system that isn’t on a rooftop or a ground-mounted array at all, but rather is completely mobile: my solar trailer.

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Mods Turn Junk UPS Into A Long-Endurance Beast

December 15, 2023 by 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.

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Vehicle-to-Grid Made Easy

May 25, 2023 by 37 Comments

As electric cars continue to see increased adoption, one associated technology that was touted long ago that still hasn’t seen widespread adoption is vehicle-to-grid or vehicle-to-home. Since most cars are parked most of the time, this would allow the cars to perform load-levelling for the grid or even act as emergency generators on an individual basis when needed. While this hasn’t panned out for a variety of reasons, it is still possible to use an EV battery for use off-grid or as part of a grid tie solar system, and now you can do it without needing to disassemble the battery packs at all.

Normally when attempting to use a scrapped EV battery for another use, the cells would be removed from the OEM pack and reorganized to a specific voltage. This build, however, eliminates the need to modify the packs at all. A LilyGO ESP32 is used to convert the CAN bus messages from the battery pack to the Modbus communications protocol used by the inverters, in this case a Fronius Gen24, so the inverter and battery can coordinate energy delivery from one to the other automatically. With the hard part out of the way, the only other requirements are to connect a high voltage DC cable from the battery pack to the inverter.

[Dala], the creator of this project, has taken other steps to ensure safety as well that we’d recommend anyone attempting to recreate this build pays close attention to, as these battery packs contain an extremely large amount of energy. The system itself supports battery packs from Nissan Leafs as well as the Tesla Model 3, which can usually be found for comparably low prices. Building battery energy storage systems to make up for the lack of commercially-available vehicle-to-home systems isn’t the only use for an old EV battery, though. For example, it’s possible to use Leaf batteries to triple the range of other EVs like [Muxsan] did with this Nissan van.

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