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Lithium-Ion Battery Hotswapping, Polarity, Holders

September 11, 2024 by 28 Comments

Everyone loves, and should respect, lithium-ion batteries. They pack a ton of power and can make our projects work better. I’ve gathered a number of tips and tricks about using them over the years, based on my own hacking and also lessons I’ve learned from others.

This installment includes a grab-bag of LiIon tricks that will help you supercharge your battery use, avoid some mistakes, and make your circuits even safer. Plus, I have a wonderful project that I just have to share.

Hot-swapping Cells

When your device runs out of juice, you might not always want to chain yourself to a wall charger. Wouldn’t it be cool if you could just hot-swap cells? Indeed it is, I’ve been doing it for years, it’s dead simple to support, but you can also do it wrong. Let me show you how to do it right!

Recently, a new handheld has hit the hacker markets – the Hackberry Pi. With a Blackberry keyboard and a colour screen, it’s a pretty standard entry into the trend of handheld Pi Zero-backed computers with Blackberry keyboards. It’s not open-source and the author does not plan to open-source its hardware, so I want to make it absolutely clear I don’t consider it hacker-friendly or worth promoting. It did publish schematics, though, and these helped me find a dangerous mistake that the first revision made when trying to implement LiIon battery hot-swap. Continue reading “Lithium-Ion Battery Hotswapping, Polarity, Holders” →

Lithium-Ion Batteries Power Your Devboards Easily

March 14, 2024 by 25 Comments

Last summer, I was hanging out with a friend from Netherlands for a week, and in the middle of that week, we decided to go on a 20 km bike trip to a nearby beach. Problem? We wanted to chat throughout the trip, but the wind noise was loud, and screaming at each other while cycling wouldn’t have been fun. I had some walkie-talkie software in mind, but only a single battery-powered Pi in my possession. So, I went into my workshop room, and half an hour later, walked out with a Pi Zero wrapped in a few cables.

I wish I could tell you that it worked out wonders. The Zero didn’t have enough CPU power, I only had single-core ones spare, and the software I had in mind would start to badly stutter every time we tried to run it in bidirectional mode. But the battery power solution was fantastic. If you need your hack to go mobile, read on.

Continue reading “Lithium-Ion Batteries Power Your Devboards Easily” →

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.

Continue reading “Lithium-Ion Battery Circuitry Is Simple” →

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” →