battery

406 Articles

Crusty Leaking Cells Kill Your Tech. Just What’s Going On?

October 19, 2022 by 83 Comments

Seasoned Hackaday readers may have noticed over the years, that some of us who toil under the sign of the Jolly Wrencher have a penchant for older tech. After all, what’s not to like in a dirt cheap piece of consumer electronics from decades past that’s just begging for a bit of hardware hacking? For me at the moment this is manifesting itself in a selection of 8mm movie cameras, as I pursue a project that will eventually deliver a decent quality digital film cartridge.

When A Cell Is From West Germany, You Know It’s Old

A leaky Duracell, "Made In West Germany"
“Made in West Germany”

The trouble with scouring junk shops for a technology superseded four decades ago is that the cameras I find have in most cases been sitting in a drawer since the early 1980s. They were a valuable item back in the day so of course they were hung on to, then they were forgotten about until one day the grown-ups who were once the kids featured in the home movies are clearing the house, and they start their journey to my bench.

The problem is that very few owners of 8mm cameras had the good sense to remove their batteries before putting them away, so I inevitably end up with a battery compartment full of crusty 1980s Duracells and rusted contacts. This has left me curious, just what has happened here and how can I fix it?

What’s The Leaky Stuff?

Construction of a zinc-manganese "alkaline" cell.
Construction of a zinc-manganese “alkaline” cell. Tympanus, Public domain.

Non-rechargeable cells come in a variety of chemistries, but the commercial ones we’re most familiar with are zinc-carbon “dry cells”, and “Alkaline” zinc-manganese dioxide cells. The zinc-carbon variety are becoming less common here in 2022 and have an acidic zinc chloride or ammonium chloride electrolyte, while the alkaline cells have a higher capacity and a basic potassium hydroxide electrolyte. They both have different failure modes that result in the leaky cells, so it’s worth taking a look at each one.

The failure mode of a zinc-carbon cell is a chemical one, the acidic electrolyte reacts with the zinc can anode, and eventually eats through it. The leaking electrolyte then attacks the surrounding circuitry and battery clips. It’s hardly a concentrated acid, but it’s enough to do plenty of damage over the years.

Meanwhile an alkaline cell has a build-up of hydrogen as it degrades. It incorporates a vent which allows the hydrogen to escape, however the hydrogen pressure can instead force the electrolyte out through this vent. The electrolyte will then corrode the battery terminals and any other electronics it touches. A feature of alkaline cell leakage is a white crust, this is potassium carbonate formed from the reaction between the potassium hydroxide electrolyte and carbon dioxide in the air.

The Global Parts Bin To The Rescue

Fresh and new battery clips for AA holders
Fresh and new battery clips for AA holders

How much damage has been done is usually a function of how long the leaking batteries have been in the device. Sometimes one is lucky and the battery contacts are salvageable, otherwise they are too far gone and a replacement has to be found. A past me tried all sorts of home-made solutions using stiff copper wire and other materials, but today thanks to the miracle of international commerce it’s usually possible to find a contact the same as or very similar to the old one. A quick AliExpress search on terms such as “AA battery spring” will return numerous options, and it’s simply a case then of paging through to find the one you need on the terms you like.

So those of you who like retro tech will find something familiar in the last few paragraphs, but there’s a lesson to be found in dealing with ancient batteries. Here in 2022 we’re more likely to have lithium polymer cells in our consumer devices and so the need to keep a pile of Duracells at hand is reduced. But the thought of today’s equivalent of a Super 8 camera lying forgotten in a drawer for decades with a cheap li-po pouch cell inside it is far more frightening than something with some crusty manganese cells. Have we just found the root cause of house fires in the 2040s?

Mining And Refining: Cobalt, The Unfortunately Necessary Metal

October 18, 2022 by 21 Comments

The story of humankind is largely a tale of conflict, often brought about by the uneven distribution of resources. For as long as we’ve been down out of the trees, and probably considerably before that too, our ancestors have been struggling to get what they need to survive, as often as not at the expense of another, more fortunate tribe. Food, water, land, it doesn’t matter; if They have it and We don’t, chances are good that there’s going to be a fight.

Few resources are as unevenly distributed across our planet as cobalt is. The metal makes up only a fraction of a percent of the Earth’s crust, and commercially significant concentrations are few and far between, enough so that those who have some often end up at odds with those who need it. And need it we do; what started in antiquity as mainly a rich blue pigment for glass and ceramics has become essential for important industrial alloys, high-power magnets, and the anodes of lithium batteries, among other uses.

Getting access to our limited supply of cobalt and refining it into a useful metal isn’t a trivial process, and unfortunately its outsized importance to technological society forces it into a geopolitical role that has done a lot to add to human misery. Luckily, market forces and new technology are making once-marginal sources viable, which just may help us get the cobalt we need without all the conflict.

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Lithium-Ion Battery Circuitry Is Simple

October 10, 2022 by 55 Comments

By now, we’ve gone through LiIon handling basics and mechanics. When it comes to designing your circuit around a LiIon battery, I believe you could benefit from a cookbook with direct suggestions, too. Here, I’d like to give you a collection of LiIon recipes that worked well for me over the years.

I will be talking about single-series (1sXp) cell configurations, for a simple reason – multiple-series configurations are not something I consider myself as having worked extensively with. The single-series configurations alone will result in a fairly extensive writeup, but for those savvy in LiIon handling, I invite you to share your tips, tricks and observations in the comment section – last time, we had a fair few interesting points brought up!

The Friendly Neighborhood Charger

There’s a whole bunch of ways to charge the cells you’ve just added to your device – a wide variety of charger ICs and other solutions are at your disposal. I’d like to focus on one specific module that I believe it’s important you know more about.

You likely have seen the blue TP4056 boards around – they’re cheap and you’re one Aliexpress order away from owning a bunch, with a dozen boards going for only a few bucks. The TP4056 is a LiIon charger IC able to top up your cells at rate of up to 1 A. Many TP4056 boards have a protection circuit built in, which means that such a board can protect your LiIon cell from the external world, too. This board itself can be treated as a module; for over half a decade now, the PCB footprint has stayed the same, to the point where you can add a TP4056 board footprint onto your own PCBs if you need LiIon charging and protection. I do that a lot – it’s way easier, and even cheaper, than soldering the TP4056 and all its support components. Here’s a KiCad footprint if you’d like to do that too.

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Thank Magnesium For Water-Activated Batteries

October 4, 2022 by 16 Comments

Most of the batteries we use these days, whether rechargeable or not, are generally self-contained affairs. They come in a sealed package, with the anode, cathode, and electrolyte all wrapped up inside a stout plastic or metal casing. All the reactive chemicals stay inside.

However, a certain class of magnesium batteries are manufactured in a dry, unreactive state. To switch these batteries on, all you need to do is add water! Let’s take a look at these useful devices, and explore some of their applications.

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Lithium-Ion Batteries Are Easy To Find

October 3, 2022 by 43 Comments

In the first article, I’ve given you an overview of Lithium-Ion batteries and cells as building blocks for our projects, and described how hackers should treat their Lithium-Ion cells. But what if you don’t have any LiIon cells yet? Where do you get LiIon cells for your project?

Taking laptop batteries apart,  whether the regular 18650 or the modern pouch cell-based ones, remains a good avenue – many hackers take this road and the topic is extensively covered by a number of people. However, a 18650 cell might not fit your project size-wise, and thin batteries haven’t quite flooded the market yet. Let’s see what your options are beyond laptops. Continue reading “Lithium-Ion Batteries Are Easy To Find” →

24 Hours Of Le Airplanes

September 27, 2022 by 22 Comments

There’s no more famous road endurance race than the 24 Hours of Le Mans, where teams compete to see how far they can drive in a single 24-hour window. The race presents unique challenges not found in other types of racing. While RC airplanes may not have a similar race, [Daniel] a.k.a. [rctestflight] created a similar challenge for himself by attempting to fly an RC airplane non-stop for as long as he could, and a whole host of interesting situations cropped up before and during flight.

In order for an RC plane to fly for an entire day, it essentially needs to be solar powered. A large amount of strategy goes into a design of this sort. For one, the wing shape needs to be efficient in flight but not reduce the amount of area available for solar panels. For another, the start time of the flight needs to be balanced against the position of the sun in the sky. With these variables more or less fixed, [Daniel] began his flight.

It started off well enough, with the plane in an autonomous “return to home” mode which allowed it to continually circle overhead without direct human control. But after taking a break to fly it in FPV mode, [Daniel] noticed that the voltage on his battery was extremely high. It turned out that the solar charge controller wasn’t operating as expected and was shunting a large amount of solar energy directly into the battery. He landed and immediately removed the “spicy pillow” to avoid any sort of nonlinear event. With a new battery in the plane he began the flight again.

Even after all of that, [Daniel] still had some issues stemming from the aerodynamic nature of this plane specifically. There were some issues with wind, and with the flight controller not recognizing the correct “home” position, but all in all it seems like a fun day of flying a plane. If your idea of “fun” is sitting around and occasionally looking up for eight and a half hours. For more of [Daniel]’s long-term autonomous piloting, be sure to take a look at his solar tugboat as well.

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Lithium-Ion Batteries Are Your Friends

September 6, 2022 by 56 Comments

Need some kind of battery for a project? You can always find a few Lithium-Ion (LiIon) batteries around! They’re in our phones, laptops, and a myriad other battery-powered things of all forms – as hackers, we will find ourselves working with them more and more. Lithium-Ion batteries are unmatched when it comes to energy capacity, ease of charging, and all the shapes and sizes you can get one in.

There’s also misconceptions about these batteries – bad advice floating around, fearmongering videos of devices ablaze, as well as mundane lack of understanding. Today, I’d like to provide a general overview of how to treat your LiIon batteries properly, making sure they serve you well long-term.

What’s A Battery? A Malleable Pile Of Cells

Lithium-Ion batteries are our friends. Now, there can’t be a proper friendship if you two don’t understand each other. Lithium-Ion batteries are tailored for human needs by the factory that produced them. As for us hackers, we’ll want to learn some things.

First thing to learn – a single LiIon “unit” is called a cell. An average laptop contains three or six Li-Ion cells, a phone will have one, a tablet will have from one to three. What we refer to as “battery” is typically one or multiple cells, together with protection circuitry, casing and a separate connector – most of the time all three of these, but not always. The typical voltage is 3.6 V or 3.7 V, with maximum voltage being 4.2 V – these are chemistry-defined, the same for most kinds of cells and almost always written on the cell. Continue reading “Lithium-Ion Batteries Are Your Friends” →