battery

404 Articles

The 19th Century, When Gravity Battery Meant Something Different

May 16, 2020 by 19 Comments

The internet is full of dubious content promoting “free energy” devices and other ideas that stretch credibility, so [Robert Murray-Smith] prefaces his demonstration of a gravity battery with a warning to look elsewhere if you are in search of such things. Instead he’s showing us a pair of cells from The Model Engineer and Amateur Electrician, a printed periodical that sounds to us something like an equivalent of Hackaday from the 1890s. (Video embedded below.)

The cells are termed gravity batteries because their constituents settle out into layers not unlike a tequila sunrise under the influence of gravity, something that made them especially suitable for the home constructor in the late 19th century when there were no handy wall outlets from which to snag a bit of power.

The chemistry of each is not unexpected if you spent any time in your high school’s lab, a zinc-copper primary cell with a zinc sulphate/copper sulphate electrolyte and a secondary zinc-carbon cell with a zinc bromide electrolyte and a layer of bromine forming on charging. The construction in large glass vessels is archaic though, and it’s this that’s prompted his video. He poses the question whether this type of cell might be revived using 21st century techniques to produce something of use today. The video is below the break, and even if you are not about to try your hand at electrochemistry it’s an interesting watch.

Thanks [Blaubär] for the tip! Continue reading “The 19th Century, When Gravity Battery Meant Something Different” →

A CR2032 Battery Eliminator

April 24, 2020 by 26 Comments

Back when batteries were expensive and low-capacity, it was common to buy a “battery eliminator” that could substitute for common battery configurations. [David Watts] must remember those, because he decided to make an eliminator for all the CR2032 battery-driven gear he has. He got some brass blanks about the size of the battery, and you can see the results on the video below.

His first attempt seemed to work fairly well, a sandwich of two brass disks, each with a Velcro spacer and wires soldered on to connect to a power supply. The fake battery looks as though it might be a little thick, but it did work once the battery holder was persuaded to accept it.

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Microbatteries On The Grid

March 27, 2020 by 35 Comments

Not everybody has $6500 to toss into a Tesla Powerwall (and that’s a low estimate), but if you want the benefits of battery storage for your house, [Matt]’s modular “microbattery” storage system might be right up your alley. With a build-as-you-go model, virtually any battery can be placed on the grid in order to start storing power from a small solar installation or other power source.

The system works how any other battery installation would work. When demand is high, a series of microinverters turn on and deliver power to the grid. When demand is low, the batteries get charged. The major difference between this setup and a consumer-grade system is that this system is highly modular and each module is networked together to improve the efficiency of the overall system. Its all tied together with a Raspberry Pi that manages the entire setup.

While all of the software is available to set this up, it should go without saying that working with mains power is dangerous, besides the fact that you’ll need inverters capable of matching phase angle with the grid, a meter that handles reverse power flow, a power company that is willing to take the power, and a number of building code statutes to appease. If you don’t have all that together, you might want to go off-grid instead.

Solar Panel Keeps Car Battery Topped Off Through OBD-II Port

March 10, 2020 by 47 Comments

Up until the 1980s or so, a mechanic could check for shorts in a car’s electrical system by looking for sparks while removing the battery terminal with everything turned off in the car. That stopped being possible when cars started getting always-on devices, and as [Kerry Wong] learned, these phantom loads can leave one stranded with a dead battery at the airport after returning from a long trip.

[Kerry]’s solution is simple: a solar trickle charger. Such devices are readily available commercially, of course, and generally consist of a small photovoltaic array that sits on the dashboard and a plug for the lighter socket. But as [Kerry] points out in the video below, most newer model cars no longer have lighter sockets that are wired to work without the ignition being on. So he chose to connect his solar panel directly to the OBD-II port, the spec for which calls for an always-on, fused circuit connected directly to the positive terminal of the vehicle battery. He had to hack together an adapter for the panel’s lighter plug, the insides of which are more than a little scary, and for good measure, he added a Schottky diode to prevent battery discharge through the panel. Even the weak winter sun provides 150 mA or so of trickle charge, and [Kerry] can rest assured his ride will be ready at the end of his trip.

We used to seeing [Kerry] tear down test gear and analyze unusual devices, along with the odd post mortem on nearly catastrophic failures. We’re glad nothing burst into flames with this one.

Continue reading “Solar Panel Keeps Car Battery Topped Off Through OBD-II Port” →

Lighting Up A Tiny Train Needs Tiny Tools

March 4, 2020 by 11 Comments

A tiny toy train that [voidnill] illuminated with a small LED strip fragment demonstrates several challenges that come with both modifying existing products, and working with small things in general. One is that it is hard in general to work around existing design choices and materials when modifying something. The second is that problems are magnified with everything is so small.

[voidnill]’s plentiful photos illustrate everything from drilling out small rivets and tapping the holes for screws to installing a tiny switch, LED strip, and button cells as a power supply. When things are so small, some of the usual solutions don’t apply. For example, cyanoacrylate glue may seem like a good idea for mounting small plastic parts, but CA glue easily wicks into components like the tiny power switch and gums up the insides, rendering it useless.

[voidnill] uses lots of careful cutting and patience to get everything done, and demonstrates the importance of quality tools. The LED strip fragment is driven by three small button cells, and while tape does a serviceable job as a battery holder, [voidnill] believes a 3D printed custom frame for the cells would really do the trick.

The kind of work that goes into making or modifying small things really puts into perspective the amount of effort behind projects like this coffee table with an N-gauge model railway inside it.

Fun-Size Tesla Might Be The World’s Smallest

February 22, 2020 by 13 Comments

We get all kinds of tips about “the world’s something-est” widget, which normally end up attracting the debunkers in droves. So normally, we shy away from making superlative claims about a project, no matter how they bill themselves. But we’re comfortable that this is the world’s smallest Tesla, at least if we have to stretch the definition of Tesla a bit.

This clown-car version of the Tesla Model S that [Austin] built is based around a Radio Flyer replica of the electric sedan. The $600 battery-powered original doesn’t deliver exactly the same neck-snapping acceleration of its full-size cousin, so he stripped off the nicely detailed plastic body and put that onto a heavily modified go-cart chassis. The tiny wheelbase left little in the way of legroom, but with the seat mounted far enough back into the wheelie-inducing zone, it was possible for [Austin] to squeeze in. He chose to pay homage to Tesla’s battery pack design and built 16 modules with fourteen 18650 cells in each, a still-substantial battery for such a small vehicle. Hydraulic brakes were also added, a wise decision since the 4800 Watt BLDC is a little snappier than the stock motor, to say the least. The video below shows the build, as well as a dangerous test ride where the speed read 72 at one point; we’re not sure if that’s MPH or km/h, but either way, it’s terrifying. The drifts were pretty sick too.

It seems [Austin] has the need for speed, and for drifting.  We’ve seen his water-cooled electric drift trike before, as well as his ridiculously overpowered crazy cart.

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Cheap Strain Relief By Casting Hot Glue In A 3D Print

February 11, 2020 by 53 Comments

[Daniel Roibert] found a way to add cheap strain relief to JST-XH connectors, better known to hobby aircraft folks as the charging and balance connectors on lithium-polymer battery packs. His solution is to cast them in hot glue, with the help of 3D printed molds. His project provides molds fitted for connectors with anywhere from two to eight conductors, so just pick the appropriate one and get printing. [Daniel] says to print the mold pieces in PETG, so that they can hold up to the temperature of melted glue.

The 3D models aren’t particularly intuitive to look at, but an instructional video makes everything clear. First coat the inside surfaces of the mold with a release agent (something like silicone oil should do the trick) and then a small amount of hot glue goes in the bottom. Next the connector is laid down on top of the glue, more glue is applied, and the top of the mold is pressed in. The small hole in the top isn’t for filling with glue, it’s to let excess escape as the mold is closed. After things cool completely, just pop apart the mold (little cutouts for a screwdriver tip make this easy) and trim any excess. That’s all there is to it.

One last thing: among the downloads you may notice one additional model. That one is provided in split parts, so that one can make a mold of an arbitrary width just by stretching the middle parts as needed, then merging them together. After all, sometimes the STL file is just not quite right and if sharing CAD files is not an option for whatever reason, providing STLs that can be more easily tweaked is a welcome courtesy. You can watch a short video showing how the whole thing works, below.

Continue reading “Cheap Strain Relief By Casting Hot Glue In A 3D Print” →