MagSafe Power Bank from Scrap

Just a few short years ago, it was possible to find scrapped lithium batteries for free, or at least for very cheap. What most people at the time didn’t realize is that a battery with multiple cells might go bad because only one cell is bad, leaving the others ready for salvaging. Now it’s not a secret anymore, but if you can manage to get your hands on some there’s a lot of options for use. [ijsf] took a step further with this hack, taking a few cells from a Panasonic battery and wrangling them into a MagSafe-capable power bank for a Mac.

The real hack wasn’t scavenging batteries, however, it was getting the MagSafe to signal the computer to use power from the battery bank to run the computer only, and not to use any of that energy for charging the computer’s internal batteries. This is achieved by disabling the center MagSafe pin, which is the computer’s communication line to the power adapter. After that, the battery bank could be programmed to behave properly (a feat in itself for lithium batteries) and the power bank was successfully put into operation.

Not only was this hack a great guide for how to repurpose cells from a “dead” battery, it’s also an unparalleled quick reference for any work that might need a MagSafe connector. Of course, if you’re going to work with these chargers, make sure that you’re using one that isn’t a cheap clone.

Stealing Joules From An Aluminium-Air Battery

While batteries are cheap and readily obtainable today, sometimes it’s still fun to mess around with their less-common manifestations. Experimenting with a few configurations, Hackaday.io user [will.stevens] has assembled an aluminium-air battery and combined it with a joule thief to light an LED.

To build the air battery, soak an activated charcoal puck — from a water filter, for example — in salt-saturated water while you cut the base off an aluminium can. A circle of tissue paper — also saturated with the salt water — is pressed between the bare charcoal disk and the can, taking care not to rip the paper, and topped off with a penny and a bit of wire. Once clamped together, the reaction is able to power an LED via a simple joule thief.

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Innovating A Backyard Solar Battery System

Ever on the lookout for creative applications for tech, [Andres Leon] built a solar powered battery system to keep his Christmas lights shining. It worked, but — pushing for innovation — it is now capable of so much more.

The shorthand of this system is two, 100 amp-hour, deep-cycle AGM batteries charged by four, 100 W solar panels mounted on an adjustable angle wood frame. Once back at the drawing board, however, [Leon] wanted to be able track real-time statistics of power collected, stored and discharged, and the ability to control it remotely. So, he introduced a Raspberry Pi running Raspbian Jessie Lite that publishes all the collected data to Home Assistant to be accessed and enable control of the system from the convenience of his smartphone. A pair of Arduino Deuemilanoves reporting to the Pi control a solid state relay powering a 12 V, 800 W DC-to-AC inverter and monitor a linear current sensor — although the latter still needs some tinkering. A in-depth video tour of the system follows after the break!

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Rescuing A Proprietary Battery Pack With A Cell From A Camera

If you have an older handheld battery-powered device, you may be fighting a diminishing battery capacity as its lithium-ion cells reach the end of their life. And if you are like [Foxx D’Gamma], whose device is an Alinco DJ-C7 handheld transceiver, you face the complete lack of availability of replacement battery packs. All is not lost though, because as he explains in the video below the break, he noticed that a digital camera battery uses a very similar-sized cell, and was able to graft the camera battery into the shell of the Alinco pack.

Cracking open the Alinco pack, he was rewarded with the rectangular Li-Ion cell and two PCBs, one for the connector and another for the battery management circuitry. By comparison the camera battery had a much smaller battery management PCB, and it fit neatly into the space vacated by the Alinco cell once those covers had been removed. A fiddly soldering job to attach the connector PCB, and he was rewarded with a working Alinco pack and an unexpected bonus when he found out that the transceiver was a dual band model.

Along the way he’s at pains to point out the safety aspects of handling Li-Ion cells, and to ensure that the polarity of the cell is correct. It’s also worth our reminding readers that these packs must always be accompanied by their battery management circuitry. The result though is pleasing: a redundant piece of equipment made obsolete by a proprietary battery, given a new lease on life.

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Solar Bulldozer Gets Dirty

As the threat of climate change looms, more and more industries are starting to electrify rather than using traditional fuel sources like gasoline and diesel. It almost all cases, the efficiency gains turn out to be environmentally and economically beneficial. Obviously we have seen more electric cars on the roads, but this trend extends far beyond automobiles to things like lawn equipment, bicycles, boats, and even airplanes. The latest in this trend of electrified machines comes to us from YouTube user [J Mantzel] who has built his own solar-powered bulldozer.

The fact that this bulldozer is completely solar-powered is only the tip of the iceberg, however. The even more impressive part is that this bulldozer was built completely from scratch. The solar panel on the roof charges a set of batteries that drive the motors, and even though the bulldozer is slow it’s incredibly strong for its small size. It’s also possible for it to operate on solar alone if it’s sunny enough, which almost eliminates the need for the batteries entirely. It’s also built out of stainless steel and aluminum, which makes it mostly rust-proof.

This is an impressive build that goes along well with [J Mantzel]’s other projects, most of which center around an off-grid lifestyle. If that’s up your alley, there is a lot of inspiration to be had from his various projects. Be sure to check out the video of his bulldozer below as well. You don’t have to build an off-grid bulldozer to get started in the world of living off-the-grid, though, and it’s easy to start small with just one solar panel and a truck.

Thanks to [Darko] for the tip!

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A Mobile Bar In A Trailer!

Ok, there are some worthy laws in place regulating the sale and distribution of alcohol — and for good reason. For many a bootlegger, however, the dream of renovating an old trailer from 1946 into a mobile bar is a dream that must– wait, what? That already exists?

It’s no mobile workshop, but the bar was initially built to accommodate guests at their wedding. [HelloPennyBar] has shared the reconstruction process with the world. Inside, there’s everything you’d need to serve beverages, including a (double) kitchen sink. In addition to a water tank, a pair of car batteries serve as the central power with electrical work installed for interior lights, a small fan to keep the bartenders cool, exterior lights, a water pump, the trailer lights, and more exterior lights so the patrons can party the night away.

Before you say anything, [HelloPennyBar] says they would need a license to sell alcohol, but alleges that for serving alcohol at private events in their state it suffices to have an off-site responsible serving license. Furthermore, a few helpful redditors have chimed in regarding battery safety and cable-mounts, to which [HelloPennyBar] was amenable. Safety and legality noted, the mobile bar must make for a novel evening of fun.

[via /r/DIY]

DIY USB Power Bank

USB power banks give your phone some extra juice on the go. You can find them in all shapes and sizes from various retailers, but why not build your own?

[Kim] has a walkthrough on how to do just that. This DIY USB Power Bank packs 18650 battery cells and a power management board into a 3D printed case. The four cells provide 16,000 mAh, which should give you a few charges. The end product looks pretty good, and comes in a bit cheaper than buying a power bank of similar capacity.

The power management hardware being used here appears to be a generic part used in many power bank designs. It performs the necessary voltage conversions and manages charge and discharge to avoid damaging the cells. A small display shows the state of the battery pack.

You might prefer to buy a power bank off the shelf, but this design could be perfect solution for adding batteries to other projects. With a few cells and this management board, you have a stable 5 V output with USB charging. The 2.1 A output should be enough to power most boards, including Raspberry Pis. While we’ve seen other DIY Raspberry Pi power banks in the past, this board gets the job done for $3.