Save An Old Drill From Landfill, With Some Lithium-Ion Magic

What do you do, when your trusty cordless drill starts to lose battery capacity? You bought it a decade ago and parts are a distant memory, so there’s no chance of buying a new pack. If you are [Danilo Larizza], you strip away the old NiMh cells, and replace them with a custom pack (Italian, Google Translate link) made from 18650 Li-ion cells.

The build is a straightforward one to anyone familiar with lithium-ion packs, but to a battery newbie it should serve as a handy step-by-step description. He starts by selecting a range of matched cells from discarded laptop batteries and adds an off-the-shelf battery management board to keep everything safe. Interestingly he appears to have soldered his wires to the cells rather than the more usual spot-welding, sadly for many of us a spot-welder is beyond our means. It would be interesting to know both the mechanical integrity of the resulting connection and whether the heat of soldering might in some way affect the cells.

Firing up the drill with the new pack is not the immediate success he hoped it would be, the start-up current is so high that the battery management board goes into a fault condition. This situation is resolved with a model that can take more current, and he can take his drill out once more.

If you are annoyed by the rise of cordless tools, you’re in good company. Meanwhile if you lack a spot-welder for batteries, have a look at one of the nicer ones we’ve seen.

3D Printed Battery Pack Keeps Old Drill Spinning

The greatest enemy of proprietary hardware and components is time. Eventually, that little adapter cable or oddball battery pack isn’t going to be available anymore, and you’re stuck with a device that you can’t use. That’s precisely what happened to [Larry G] when the now antiquated 7.2V NiCd batteries used by his cordless drill became too hard to track down. The drill was still in great shape and worked fine, but he couldn’t power the thing. Rather than toss a working tool, he decided to 3D print his own battery pack.

The 3D modeling on the battery pack is impeccable

He could have just swapped new cells into his old pack, but if you’re going to go through all that trouble, why not improve on things a little? Rather than the NiCd batteries used by the original pack, this new pack is designed around readily available AA NiMH batteries. For the light repairs and craft work he usually gets himself into, he figures these batteries should be fine. Plus he already had them on hand, and as we all know, that’s half the battle when putting a project together.

Interestingly, the original battery pack was wired in such a way that it provided two voltages. In older tools such as this one, this would be used for rudimentary speed control. Depending on which speed setting the drill is on, it would either connect to 4 or 6 cells in the original pack. [Larry] didn’t want to get involved with the extra wiring and never used the dual speeds anyway, so his pack only offers the maximum speed setting. Though he does mention that it may be possible to do PWM speed control in the battery itself via a 555 timer if he feels like revisiting the project.

[Larry] tells us the pack itself was rendered completely from scratch, using only the original battery pack and trial-and-error to get the fit perfect. He reused the side-mounted release buttons to save time, but otherwise everything is 3D printed in PETG for its strength and chemical resistance.


This is an entry in Hackaday’s

Repairs You Can Print contest

The twenty best projects will receive $100 in Tindie credit, and for the best projects by a Student or Organization, we’ve got two brand-new Prusa i3 MK3 printers. With a printer like that, you’ll be breaking stuff around the house just to have an excuse to make replacement parts.

The Best NiMh Charger?

[Paul Allen] has been working on the latest iteration of his NiMh battery charger and it looks amazing!

We’ve covered [Paul Allen]s awesome hacks and tutorials before, but never this project. What makes his charger so special is it’s ability to monitor and log every aspect of the charging process. Not only does it have a SD card for data logging, but it also interfaces with a Windows application for real-time monitoring as well as analysis and visualization of the charging process (Linux users don’t fret it has a serial interface too).

[Paul] doesn’t say if he plans to open hardware or kickstart the charger, but some of his older posts give us a quick peak at the gerbers. Let’s hope this awesome project makes its way into the wild soon, and hopefully we’ll be able to try it for ourselves and see if it lives up to its name.

Battery Basics – Choosing a Battery for Your Project

If choosing a rechargeable battery for your project intimidates you, [Afroman] has prepared a primer video that should put you at ease. In this tutorial for battery basics he not only walks you through a choice of 5 rechargeable chemistries and their respective tradeoffs, but gives a procedure that will allow you to navigate through the specs of real-world batteries for sale – something that can be the most intimidating part of the process.

You cannot learn everything about batteries in 9 minutes, but watching this should get you from zero to the important 80% of the way there. Even if your project does not give you the specs you need to begin buying, [Afroman] tells you what to measure and how to shop for it. In particular, the information he gives is framed in the context you care about, hopefully ensuring you are not waylaid by all the details that were safe to ignore. If this is not enough, [Afroman]’s prequel video on battery terminology has more detail.

Much like your high school English teacher told you, you need to know the rules before you can choose to break them. Many of battery absolute Dos or Don’ts are written for the manufacturer, who provides for the consumer, not the hacker. Hackaday has published hundreds of battery articles over the years; search our archives when you are ready for more.

Continue reading “Battery Basics – Choosing a Battery for Your Project”

Camping light retrofitted as a solar recharging station

With grand plans of tenting out for several days at a music festival [Josh] needed a way recharge his portable devices. In the past he’s lugged around a 12V battery with him, but this year he wanted to make things easier. He ended retrofitting a camping light to do the job with the help of the summer sun.

The first step of the project was to source some rechargeable batteries. He toyed with the idea of Li-Ion cells but ended up going with NiMH because the charging is more forgiving and he got them at a great price. Because of the lower operating voltage (1.2V versus Alkaline’s 1.5V) he needed to squeeze two more into the lamp housing. Here you can see that he just managed to get them to fit in the wire-run area down the middle of the case.

Next comes the recharging circuit. He based his design around an ATmega44, using a voltage divider and the ADC to detect when the batteries are topped off. During the day this is connected to an external solar panel and it’s ready to charge his phone when he gets back at night.

Steerable bristlebot via IR control

Looking at the size of this bristlebot the first thing we wondered is where’s the battery? All we know is that it’s a rechargeable NiMH and it must be hiding under that tiny circuit board. But [Naghi Sotoudeh] didn’t just build a mindless device that jiggles its way across a table. This vibrating robot is controllable with an infrared remote control. It uses an ATtiny45 microcontroller to monitor an IR receiver for user input. An RC5 compatible television remote control lets you send commands, driving the tiny form factor in more ways than we thought possible. Check out the video after the break to see how well the two vibrating motors work at propelling the device. They’re driven using a PWM signal with makes for better control, but it doesn’t look like there’s any protection circuitry which raises concern for the longevity of the uC.

This build was featured in a larger post over at Hizook which details the history of vibrating robots. It’s not technically a bristlebot since it doesn’t ride on top of a brush, but the concept is the same. You could give your miniature fabrication skills a try in order to replicate this, or you can build a much larger version that is also steerable.

Continue reading “Steerable bristlebot via IR control”

Fixing motorized window shutter battery problems

rolling_shutter_battery_fix

Living in a brushfire-prone area, [Erich] had a set of roller shutters installed to protect his home. Mains power can be spotty in emergencies, so the shutters are powered by NiMH batteries which are housed inside the shutters’ remote control units. After encountering a good handful of dead batteries, he decided it was time to search around for a better means of powering the shutters rather than pay another $80 AUD for batteries that he knew would fail in short order.

After disassembling the shutters and the remotes, he found a litany of problems. The remotes are ATMega-based, so he assumed the programming was robust, but he found that the charging algorithm was quite poorly implemented. The batteries were allowed to get extremely hot while charging, a result of the fact that charging was done for a set period of time rather than monitoring battery voltage. Additionally, the shutter motors required a 4 amp instantaneous current when activated, something that seemed to contribute to the quick draining of the 1500 mAH battery packs.

To remedy his issues, he upgraded to a much larger sealed lead acid battery pack, which he mounted in a wall cavity. The remotes were tweaked to add a modular power plug, enabling him to easily connect and disconnect the remotes as needed. Not only did he save a ton of money on constantly replacing batteries, he’s got a nice 12v power supply in the wall that he can tap into at will.