Battery Hacks

81 Articles

Lithium-Ion Battery Hotswapping, Polarity, Holders

September 11, 2024 by 29 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” →

The Trashiest Of Mains Inverters

August 31, 2024 by 21 Comments

Switch-mode technology has made inverters which take a low DC voltage and turn it into a usable mains voltage within the reach of everybody. But still, there might be moments when a mains supply is needed and you’re not lucky enough to have AliExpress at your fingertips, and for that, here’s [Rulof] with a mains inverter that is simultaneously awful and awesome. He’s made a rotary converter, from trash and off the shelf parts.

While a switch-mode converter operates using PWM at many times the output frequency for efficiency, we’re guessing that most readers will be familiar enough with how AC works to see how a low frequency converter turns DC into AC. A set of switches repeatedly flip the polarity, and the resulting square wave is fed into a transformer to step up to the final voltage. The switches can be mechanical as with old-style converters that used vibrating reeds or rotary armatures, or they can be electronic using power transistors. In this case they are a set of microswitches actuated by a set of cams on a shaft driven by a small motor, and the transformer comes from a surplus UPS.

We’re guessing that the frequency will be only a few Hz and the microswitches will suffer from switching such an inductive load, but as you can see in the video below the break it does light a mains bulb, and we’re guessing it would be enough to activate most wall-wart switching power supplies. We’re not so sure though about his use of the IEC sockets from the UPS to carry 12 volts, as the current may be a little much for them.

Meanwhile if you thirst for more of this kind of thing, we have you covered.

Continue reading “The Trashiest Of Mains Inverters” →

Universal Power Bank Customized To Your Liking

August 31, 2024 by 10 Comments

One of the most troubling trends of almost every modern consumer product that uses electricity is that the software that controls the product is likely to be proprietary and closed-source, which could be doing (or not doing) any number of things that its owner has no control over. Whether it’s a computer, kitchen appliance, or even a device that handles the electricity directly, it’s fairly rare to find something with software that’s open and customizable. That’s why [Traditional-Code9728] is working on a power bank with an open-source firmware.

From a hardware perspective the power bank is fairly open as well, with a number of options for connecting this device to anything else that might need power. It sports a bidirectional USB-C port as well as a DC barrel plug, either of which can either charge other devices or receive energy to charge its own battery. These ports can also accept energy from a solar panel and have MPPT built in. There’s also dual USB-A ports which can provide anywhere from five to 12 volts at 25 watts, and a color screen which shows the current status of the device.

While this is a prototype device, it’s still actively being worked on. Some future planned upgrades to the power bank include a slimmer design, charge limiting features to improve battery life, and more fine-tuned control of the output voltage and current on the USB-C port. With all of the software being open-source, as well as the circuit diagram and 3D printing files, it could find itself in plenty of applications as well. This power bank also stays under the energy limits for flying on most commercial airlines as well, but if you don’t plan on taking your power bank on an airplane then you might want to try out this 2000-watt monster instead.

Hardware Reuse: The PMG001 Integrated Power Management Module

August 27, 2024 by 15 Comments

Battery management is a tedious but necessary problem that becomes more of a hassle with lithium-ion technology. As we’re all very aware, such batteries need a bit of care to be utilized safely, and as such, a huge plethora of ICs are available to perform the relevant duties. Hackaday.IO user [Erik] clearly spent some time dropping down the same old set of ICs to manage a battery in their applications, so they created a drop-in castellated PCB to manage all this.

Continue reading “Hardware Reuse: The PMG001 Integrated Power Management Module” →

Maker [Dala] showing powerwall statistics

From Vehicle-to-Grid To DIY Home Powerwalls

August 13, 2024 by 47 Comments

As battery-to-grid and vehicle-to-home technologies become increasingly mainstream, the potential for repurposing electric vehicle (EV) batteries has grown significantly. No longer just a niche pursuit, using retired EV batteries for home energy storage has become more accessible and appealing, especially as advancements in DIY solutions continue to emerge. Last year, this project by [Dala] showcased how to repurpose Nissan Leaf and Tesla Model 3 battery packs for home energy storage using a LilyGO ESP32, simplifying the process by eliminating the need for battery disassembly.

In the past few months, this project has seen remarkable progress. It now supports over 20 different solar inverter brands and more than 25 EV battery models. The most exciting development, however, is the newly developed method for chaining two EV packs together to create a single large super-battery. This breakthrough enables the combination of, for example, two 100kWh Tesla packs into a massive 200kWh storage system. This new capability offers an accessible and affordable way to build large-scale DIY home powerwalls, providing performance that rivals commercial systems at a fraction of the cost.

With these advancements, the possibilities for creating powerful, cost-effective energy storage solutions have expanded significantly. We do however stress to put safety first at all times.

Hungry for more home powerbanks? We’ve been there before.

Continue reading “From Vehicle-to-Grid To DIY Home Powerwalls” →

Better Battery Design Through Science

August 2, 2024 by 6 Comments

Before the age of lithium batteries, any project needing to carry its own power had to rely on batteries that were much less energy-dense and affordable. In many ways, we take modern lithium technology for granted, and can easily put massive batteries in our projects by the standards of just a few decades ago. While the affordability of lithium batteries has certainly decreased the amount of energy we need to put in to our projects to properly size batteries, there’s still a lot of work to be done if you’re working on a bigger project or just want to get the maximize the efficiency and effectiveness of your DIY battery pack.

The main problem with choosing a battery, as [ionworks] explains, is that batteries can’t be built for both high energy and high power, at least not without making major concessions for weight or cost. After diving in to all of the possible ways of customizing a battery, the battery guide jumps in to using PyBaMM to perform computational modeling of potential battery designs to hopefully avoid the cumbersome task of testing all of the possible ways of building a battery. With this tool virtually all of a battery’s characteristics can be simulated and potential problems with your setup can be uncovered before you chose (or start production of) a specific battery system.

While customizing a battery pack to this extent might not be a consideration for most of us unless the project is going to be big enough to run something like an electric car or a whole-house generator, it’s a worthwhile tool to know about as even smaller projects like ebikes can benefit from choosing the right cell for the application. Some of the nuances of battery pack design can be found in this guide to building packs from the standard 18650 cells.

Header: Lead holder, CC BY-SA 3.0 .

A man's hand with a black ring touches a white box. It is square on the bottom and has a sloped top. Various AC, 12V, and USB ports adorn its surface. It's approximately the size of a human head.

DIY Off Grid Battery Pack From EV Battery

July 31, 2024 by 15 Comments

Car camping gets you out in the great outdoors, but sometimes it’s nice to bring a few comforts from home. [Ed’s Garage] has taken a module from a salvaged EV and turned it into a handy portable power station.

With 2.3 kWh of storage from the single Spark EV module, the battery pack can power [Ed]’s hotplate, lights, fridge, and other electric accessories while camping away from shore power. The inverter he selected can provide up to 1500W of AC power and his 12V converter can do 150W. Several USB ports and a wireless charging pad adorn the outside next to the waterproof AC ports. He even printed a small magnetic flashlight to reuse the light from the inverter which uses an 18650 cell that can be charged from the big battery in a charger built into the exterior of the pack.

The battery management system (BMS) has a Bluetooth module allowing for remote monitoring of state of charge and setting the maximum and minimum charge points for the pack. The whole thing comes in at 73 pounds (33 kg), and while he had originally thought to give it wheels to roll, he changed his mind once he thought more about what sort of wheels he’d need to maneuver the thing in the backcountry.

If you’re thinking of building your own power pack, why not checkout a few other builds for inspiration like this one from tool batteries or one designed to charge directly from a solar panel. Be sure you checkout our guide on how to select a BMS if you’re going to use a lithium-based chemistry.

Continue reading “DIY Off Grid Battery Pack From EV Battery” →