lithium ion

51 Articles

Fool A Drone With A Fixed Battery

January 3, 2023 by 21 Comments

Lithium-ion and lithium-polymer rechargeable batteries have given us previously impossible heights of electronics power and miniaturization, but there’s a downside they have brought along with them. When a battery pack has to contain electronics for balancing cells, it’s very easy for a manufacturer to include extra functions such as locking down the battery. Repair a battery, replace cells, or use a third-party battery, and it won’t work. [Zolly] has this with a DJI Mavic Mini pack, and shares with us a method for bypassing it.

The pack talks to the multi-rotor with a serial line, and the hack involves interrupting that line at the opportune moment to stop it telling its host that things are amiss. Which is a good start — but we can’t help hacing some misgivings around the rest of the work. Disconnecting the balance line between the two cells and fooling the Battery Management System (BMS) with a resistive divider seems to us like a recipe of disaster, as does bypassing the protection MOSFETs with a piece of wire. It may work, and in theory the cells can be charged safely with an external balance charger, but we’re not sure we’d like to have a pack thus modified lying around the shop.

It does serve as a reminder that BMS boards can sometimes infuriatingly lock their owners out. We once encountered this with a second-generation iBook battery that came back to life after a BMS reset, but it’s still not something to go into unwarily. Read our guide to battery packs and BMS boards to know more.

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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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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” →

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” →

Aluminium-Sulphur Batteries For Local Grid Storage?

September 5, 2022 by 45 Comments

Lithium-Sulphur batteries have been on the cusp of commercial availability for a little while now, but nothing much has hit the shelves as of yet. There are still issues with lifetime due to cell degradation, and news about developments seems to be drying up a little. Not to worry, because MIT have come along with a new battery technology using some of the most available and cheap materials found on this planet of ours. The Aluminium-Sulphur battery developed has very promising characteristics for use with static and automotive applications, specifically its scalability and its incredible charge/discharge performance.

The cell is based upon electrodes constructed from aluminium metal and sulphur, with a electrolyte of molten catenated chloro-aluminate salts. With an operating temperature of around 100 degrees Celsius, you’re not going to want this in a mobile phone anytime soon, but that’s not the goal. The goal is the smoothing out of renewable energy sources, and localised electricity grid balancing. A major use case would be the mass charging of battery electric vehicles. As the number of charge points increases at any given location, so does the peak current needed from the grid. Aluminium-Sulphur batteries are touted to offer the solution to ease this, with their high peak discharge current capability enabling a much higher peak power delivery at the point of use.
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When Battery Rebuilds Go Wrong: Understanding BMSs, Spot Welders, And Safety

February 16, 2022 by 41 Comments

Batteries are amazing. Batteries are horrible. Batteries are a necessary evil in today’s world of portable everything. If you’re reading this sentence, even if it’s not on a mobile device, somewhere there is a battery involved. They’re that ubiquitous. There’s another thing batteries are: Expensive! And at $350 each for a specialized battery, [Linus] of Linus Tech Tips decided to take battery repair into his own hands.

Rather than do a quick how-to video about putting new cells in an old enclosure, [Linus] does a deep dive into the equipment, skills, and safety measures needed when dealing with Lithium Ion cells. And if you watch the video through, you’ll even get to see those safety measures put to good use!

The real meat of the video comes toward the end however, with its explanation of the different Battery Management Systems (BMS), and a discussion of the difficulty of doing battery repair correctly and safely. Lastly, the video covers something a bit more sinister: Batteries that are made to resist being repaired with new cells; DRM for batteries, so to speak.

Overall we found the video informative, and we hope you do too. You might also enjoy this peek into the chemistry behind your favorite battery types.

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Screenshot from the video in question, showing 12:54 of the video, demonstrating how the electrons are being exchanged when circuit is completed

Li-ion Battery Low-Level Intricacies Explained Excellently

December 21, 2021 by 7 Comments

There’s a lot of magic in Lithium-ion batteries that we typically take for granted and don’t dig deeper into. Why is the typical full charge voltage 4.2 V and not the more convenient 5 V, why is CC/CV charging needed, and what’s up with all the fires? [The Limiting Factor] released a video that explains the low-level workings of Lithium-ion batteries in a very accessible way – specifically going into ion and electron ion exchange happening between the anode and the cathode, during both the charge and the discharge cycle. The video’s great illustrative power comes from an impressively sized investment of animation, script-writing and narration work – [The Limiting Factor] describes the effort as “16 months of animation design”, and this is no typical “whiteboard sketch” explainer video.

This is 16 minutes of pay-full-attention learning material that will have you glued to your screen, and the only reason it doesn’t explain every single thing about Lithium-ion batteries is because it’s that extensive of a topic, it would require a video series when done in a professional format like this. Instead, this is an excellent intro to help you build a core of solid understanding when it comes to Li-ion battery internals, elaborating on everything that’s relevant to the level being explored – be it the SEI layer and the organic additives, or the nitty-gritty of the ion and electron exchange specifics. We can’t help but hope that more videos like this one are coming soon (or as soon as they realistically can), expanding our understanding of all the other levels of a Li-ion battery cell.

Last video from [The Limiting Factor] was an 1-hour banger breaking down all the decisions made in a Tesla Battery Day presentation in similarly impressive level of detail, and we appreciate them making a general-purpose insight video – lately, it’s become clear we need to go more in-depth on such topics. This year, we’ve covered a great comparison between supercapacitors and batteries and suitable applications for each one of those, as well as explained the automakers’ reluctance to make their own battery cells. In 2020, we did a breakdown of alternate battery chemistries that aim to replace Li-ion in some of its important applications, so if this topic catches your attention, check those articles out, too!

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