Emergency Power Based On Cordless Drill Batteries

[Don Eduardo] took matters into his own hands after experiencing a days-long power outage at his house. And like most of us have done at least one, he managed to burn his fingers on a regulator in the process. That’s because he prototyped a way to use power tool batteries as an emergency source — basing his circuit on a 7812 linear regulator which got piping hot in no time flat.

His next autodidactic undertaking carried him into the realm of switch-mode buck converters (learn a bit about these if unfamiliar). The device steps down the ~18V output to 12V regulated for devices meant for automotive or marine. We really like see the different solutions he came up with for interfacing with the batteries which have a U-shaped prong with contacts on opposite sides.

The final iteration, which is pictured above, builds a house of cards on top of the buck converter. After regulating down to 12V he feeds the output into a “cigarette-lighter” style inverter to boost back to 110V AC. The hardware is housed inside of a scrapped charger for the batteries, with the appropriate 3-prong socket hanging out the back. We think it’s a nice touch to include LED feedback for the battery level.

We would like to hear your thoughts on this technique. Is there a better way that’s as easy and adaptive (you don’t have to alter the devices you’re powering) as this one?


56 thoughts on “Emergency Power Based On Cordless Drill Batteries

    1. Exactly. This is getting annoying.

      We get it already, grab a battery and an LM7805 or LM7812 and you can have 5v USB or 12v “Car” power. This is practically identical to the lame ass one HaD posted recently and many times before.

      And yes, we still know that switch mode converters are more efficient and cooler than linear.

      “I love to make things do what they were not designed to do” – You’re using an off the shelf battery and off the shelf voltage converter / regulator. You couldn’t get much closer to what these things were designed to do!

      I’m not discrediting what this guy has done. I’m just saying we don’t need the same “hack” published each week.

      1. So you make your own voltage converters? I’d love to see how you grow your wafer crystals. EVERY electrical component is off the shelf.

        It’s elements combined or altered to provide functionality not originally provided. That’s the literal definition of a hack.

        You’re just being a dick.

    2. Not much of a hack, I agree, but what about the two glaring typos? -done at least one -We really like see? 16 comments and I’m the only one bothered by this? It wouldn’t be so bad but I found as many typos yesterday in this same authors posts and more in other posts, I don’t have time to single out each one, but come on, how hard is it to read what you have done at least once before posting?

      1. The authors seem to think it is ‘cool’ to skip the proof-reading stage… from what I can gather, they think that because this is a blog, they are exonerated from normal journalistic standards and, besides, they are far too busy. You’d think they could afford the services of a copy editor by now…

        1. (Generously) presuming you’re not trolling…

          What makes you think writers consider it cool to skip proof-reading?

          I’m a writer for Hackaday. I try my best to proof-read but after re-reading my own article 10 times as I write and tweak it I know I miss stuff sometimes. There’s all kinds of gimmicks one can try to put themselves into the “first time I’m reading this” editing mindset, but it’s a hack, fact is I did write it and my brain just glosses over sometimes. Effort-for-effort, it’s more efficient to have fresh eyes and a copy editor.

          Probably 50% of the time I make a typo (usually just forgot a word) my editors (Mike or Brian) catch it before it’s scheduled to post.

          Why you would think that any writer thinks it’s cool to release sub-standard articles is beyond me. When it happens to me I cringe and am embarrassed and try to pay attention to how it happened so I can try to prevent it in the future.

          The quality of writing on Hackaday is generally quite (relatively) poor. Generally anyone who writes for a living had some original talent for it, went to school specifically to refine it, and gets enough practice with it that their quality is high. They are writers first and foremost. Hackaday writers are not.

          The amount of technical knowledge on Hackaday is generally quite (relatively) high. The writers are geeks who are passionate about the material who also happen to be able to write about it. They’re paid what is affordable and they’re very much part time so improvement is slow.

          Readers will complain about it both ways. We’re neither technical nor journalistic enough for everyone. I would certainly hope that in a community this size that on any given article I write there are people here who have a better technical grasp of the material. You can’t be a specialized generalist. Better writers out there on average? Absolutely. Go try to find someone from a newspaper that gets paid what we get paid, and then have them herp derp about technical stuff. You’ve all seen what happens when they try, the bungle it and make fools of themselves.

          Think of it like dating, or, perhaps just pretend you date. If you want a girl who is attractive, that’s not too difficult. If you want a girl with a great and compatible personality, that’s also not too difficult. If you want a girl with both, you’re going to struggle to find one. Keep adding criteria and watch that task get more difficult. And when you do find her, what are the chances that an attractive girl with a great personality wants anything to do with what you can offer? There are some great technical journalists out there, I’m sure Hackaday would love to be able to afford to hire them.

          Instead you get us. Technically competent on a broad range of subjects, decent but not great writers, willing to work for what Hackaday pays. Sorry dude.

          Not to excuse your criticism, it’s all valid. Typos are embarrassing and bad. But saying that any of us are so arrogant as to consider ourselves above proofreading is rather off-base.

          1. I agree, no reason to get snarky and I do sympathise with the fact that you are not a “professional” writer by trade, neither am I (thanks, by the way for adding spell check to your blog moderation, I used to compose my responses in a word processing program before pasting them here to avoid ugly errors in the past) That said I am simply expressing my disappointment at the general lack of respect for language in our world today. I also frequent the BBC’s world news website and their writers are (almost) as likely to commit language errors as the HaD crew!

          2. Miles – I agree with your criticism. It really shouldn’t happen, we have copy editors for a reason and if Hackaday wants to be taken seriously (which I think it does) I think it should act seriously. While most readers can see where we’re coming from on how errors slip through, explaining it doesn’t excuse it.

            My post was directed at eccentricelectron, who bizarrely claimed that Hackaday writers think it’s “cool” to litter their posts with errors and leave them there, or, think they’re above proofreading or whatever his point was.

            I can’t speak for other contributors but, despite not being a writer by trade, it’s not an excuse for me to communicate poorly. I spend a lot of time soliciting criticism and feedback from my readers to try to catch up to where I think I should be. Just because it’s a blog doesn’t mean it’s an excuse to half-ass it. The actual typos are just going to be a thing that happens and there should be a part of the process that catches those so I don’t worry about those that much. I worry more about making sure I say the most interesting things to the readers, cover the most interesting projects, deliver the right amount of context, etc. Things that are less concrete and harder to improve on.

          3. I read the article and the comments. I have to say that I thoroughly enjoyed the article, and wasn’t at all distracted by, or concerned with any typos. In my opinion, worrying about typos and grammar mistakes, then going so far as to point it out when it clearly in no way takes away from the article makes you an arrogant jackass.

        1. Did you mean “same author[‘]s post?” … the question mark should be inside the quotes.

          It’s the curse of the grammarnazi. It’s impossible to correct someone else without making further errors yourself. As I’m sure I have now perpetuated.

          Actually this is a stupid rule, I find in context, a quote should be a quote and the sentence’s punctuation should lie outside of it. I deliberately disobey it, being a wolf of language and not a sheep.

    3. Terrible, didn’t even smelt his own copper for the wires, what a prick!

      Everyone is at different stages of understanding, this is a good one for the novices.
      Shouldn’t hate on people like that.

  1. I’ve used Black & Decker “12V” (or close to it) lithium cordless drill batteries for this. The contacts are simply flat spring-loaded slots, you can stick a normal 1/4″ spade terminal directly into the sockets. However, this is definitely just an emergency option…you can come up with a much cheaper setup using RC packs or 18650 cells.

  2. Lol NOT A HACK. This is something a simpleton could do, not to mention they make a light that the batteries plug into.

    Video in a nutshell, Hurr durr i plugged a battery to da buck then to da bulb hurr durr den i plug battery into buk into inverter into light and uhh hurr durr

    1. Wow, you people are a bunch of elitist jerks. I am not as smart as you, so I found this useful. Pull your head out of your butt, and look at the world through other people’s eyes.

      1. I agree, Robert. These “geniuses” should take a step back and listen to themselves(or in this case read what they’ve wrote). I’ve found that the comment section has pretty much been taken over by this type of negative-thinking. Just watch their response to what I’ve said, they will prove my point. Hackaday and its user-base have changed, and not for the better.

        1. It’s true.. This is a fine “hack” that one would feel especially good about next time you are sitting there without power. It’s really easy to sit behind your keyboard and declare “that’s not a hack” — build something and submit it already.

          1. Agreed. This is something that would make you a hero for a day in a remote town that loses power. One of our neighbors had her land line freeze a couple of years ago rendering her already slow internet to nothing. Although it is not a hack, she was the happiest person ever to learn about tethering through her smartphone. Might seem simple to me, but then again I cannot grow heirloom tomatoes in these temps like she can so maybe I am the dumb one. We all have to work together on this big blue marble and pool our different talents to keep it spinning. I hope everyone continues to explore the world around them and find fun ways to make life easier.

        2. Its not negative thinking dweeb, watch the comments and see how much praise I give for genuinely clever things. This video was me in 5th grade, for Odin’s sake, quit being such a knob slobber. I can build a house out of legos with an LED porch lite, post it and I am sure idiots like you would be ready to praise it.

          As I continue to prove your point yes I am making something truly amazing and as soon as the hackaday prize is up for this year I will post. Sorry, I don’t agree with your namby mindset that everyone should get a good job trophy for every little piddly shit thing they do.

          This is a stupid, absence of hack. You can buy the flashlight that these batteries plug into for less than buying all this stuff and cobbling together a pile of shit. He didn’t do this during the outage he did it weeks later so no, not cool or useful in the least.

  3. I’ve lost more batteries to disuse, than use. Because they’re designed to fit a certain tool or tool set, and nothing else. Sometimes they get laid up a while, self-discharge, and are ruined. Or slowly cook to death on poorly designed trickle chargers. Or for lithium ions, just plain get old. Very few I’d say I got my money’s worth from. Not even close.

    [magegr] said, “you can come up with a much cheaper setup using RC packs or 18650 cells.” And this is true. But personally, I don’t need more battery packs; especially an emergency one that will see even less use – perhaps none at all before the battery dies.

    And not long ago, there was featured a hand-cranked generator for charging a cell phone in an emergency. That’s useful and was well received, but how often are you in an emergency that really requires it? Though AC power may be gone, you’re usually still surrounded by power sources. Given a 12V charger, you can charge your cell phone from a car, your UPS (direct battery connection), that pile of D cells you bought years ago on sale that went unused and are about to expire and leak, etc. (I have done all of these.)

    Yes, this is obvious, off-the-shelf, “something a simpleton could do”… Yet I see a lot of more complex solutions, while the simple seems to go overlooked. Maybe an occasional reminder is useful after all.

    1. And I think this is the crux of the argument. “A good engineer will solve a problem with a solution so complex many wouldn’t understand it. A great engineer will solve a problem with a solution so simple, you’d be kicking yourself for not thinking of it first.” – Jay Leno. Go figure.

        1. He threw something together, with parts on hand, during a power outage, and inspired to improve on it some later. It’s a hack, because he used parts he had on hand. The light, was just an example, showed it worked. You could plug in other things, though from my personal similar experience, those little inverters to power much. I sometimes need to discharge my quadcopter batteries to storage charge level, takes hours on my charger. I use a 300 watt inverter, to light a 75w incandescent bulb. Takes 30-40 minutes, and close enough to storage charge.

          Hacking isn’t about the best solution, or producing commercial products for troll to steal. Some people build things, just as proof of concept, often proves the concept wasn’t worth pursuing, or better to take a different direction. Still interesting reading, and saves others from making the same discoveries.

          I don’t know why there is so much criticism and negativity in the comments. Is anyone paying HAD to read the content? It’s free, accept the gift, for what it is, and appreciate all that is offered. Or start your own website, and make just as perfect, as you can. I’d likely stick to HAD though, I’m not perfect, and wouldn’t want to be ridiculed and shamed for my many grammatical mistakes, or silly hacks…

  4. If you get lucky and have 12 v li ion pack. You can run a 12 v inverter directly if the pack isn’t fully charged ( over volt alarm) or a fully charged pack if its large constant load to pull down the packs voltage. The only draw backs are the low battery alarm will go off when the pack is 50% and you have to watch it to make sure it doesn’t over discharge the pack.

  5. I really like this. He’s a layman, and this is his journey. I still often over engineer stuff. I have a pile of ryobi batteries lying around and was looking for a way of using them. I 3d printed holders. These older chargers are available for about $10.

    1. They have to, because car power is only nominally 12 Volts, and actually goes to 15-16 volts when the engine is running, and any device connected should be hardened to deal with up to 50-60 Volt spikes.

  6. Ok done but whole device does not make much practical sense. In first stage buck converter outputs no more than 50W (12V, max 3A, limit of switching IC). Then boost converter steps up to 110V, probably less then 40W maximum output. So you can power 110V light bulbs or phone chargers because you don’t have enough power for anything else.
    If you remove step-up circuit and leave only step-down 12V converter then you can power your bulbs & chargers from 12V and have more efficient and less dangerous system.

  7. This discussion thread reminds me of the other saying that went around the intertubes: “a technician is the one solving all the problems that the engineers created”

    This is a very hateful passive-agressive one. a GOOD technician is one that solves the problems of BAD engineers. further simplified: a GOOD problem solver solves problems created by the BAD problem solver.

    people are problem solvers: testers, engineers, technicians, artists, doctors, could we please come to terms that we are all good at some things and bad at others?

    i am sure the person who did this got te thrills everyone gets when he gets an idea that has been available fo years and years in the back of his mind, and put it in the real world. Sure, it has some possible applications, and it DOES serve as a reminder that there is more than one way to skin a cat, or to light a lightbulb. I’ve done it myself: i hooked a 14 v lipo to an automotive socket and a auto phone charger to recharge all my devices while i was on a 3 day bus trip and here is the catch: i’ve done this and plugged an inverter into it and my laptop charger into that, because that is what i had around the house. i MIGHT have bought a proper buck-boost to plug the external battery directly into the laptop but it worked well enough for the job as i did it, and it was only supposed to be a short-lived solution. guess what: the lipo failed after a while, no surprises there, for a myriad of reasons, not the least poor wire management on my behalf that might have shorted it out for a couple hundreds milliseconds.

    nevertheless, i still appreciate this type of thinking because thats how one nurtures creativity within oneself. this is how you train the brain to think outside the box, inside the box, or, for that matter, withot respect for the bounds of the box.

    but based on the comments already posted, i must say, i and a part of the readership here possibly agrees, did not come to hackaday to get help and inspiration with this type of “projects”. i already know you can solder a wire directly to a lightbulb, and plug it into the main socket, and while that is a great thing to do if you must, one would really have to know WHY you shouldn’t.

    to the editors: the way the trend is going on this website, we will soon find “hacks” like bending a paperclip into a nifty way to organize cables on your desk, or 500 ways you can use your lathe jaws to make a makeshift rotissery for your weekend barbecue. you can spend hours and hours arguing about the legitimacy of posting about this and that. nobody argues with that. but be coscious that whatever you post about will both alienate some people from your website, and make you a whole new batch of fans. it is your responsibility to choose which kind of readership you want to foster.

    now for me, hacking is about critical thinking: at the moment all articles seem to be like “this is the situation, this is the problem and this is the solution. kudos.” how about adding something along the lines of “however, if you find yourself in a different situation, you might not want to solve that problem like that, because [insert constructive criticism here]”

    getting your “hack” posted on hackaday will only be an honor as long as not everyone gets it, just the same way as it is not really a medal, if everyone participating got one. you have the responsibility to be truthful, and that includes unpleasant remarks. It’d be a shame if you just put people down for their bad designs, without pointing out the clever bits, but it is just as sad to only ever say good things about everything.

      1. I disagree that critics should be required to do better. One can competently criticize something without having the knowledge or ability to do better. There is value in honest criticism in itself. I don’t know anything about brain surgery but if I see a surgeon show up drunk and see him coughing into the brain and not able to hold the bonesaw steady… a reasonable response to me saying “Who the hell is this guy? Get him out of there.” would not be “Oh, so suddenly you’re a brain surgeon? Let’s see you try it then.”

        The expectation that “someone should” do better is the attitude which should stop. You are a someone, be at least as critical of yourself as you are of others.

        I looked through your website, a little bit. The navigation is awful and tedious. I didn’t find anything worth writing about, but I didn’t try that hard because I see better stuff than that every day on the tips line.

        When you create something you think is good enough for us to cover, do you submit it to the Hackaday tips line? Proof of the pudding is in the eating.

        Once upon a time an angry reader submitted a tip just to show us there was better stuff to cover. The article he linked was pretty good so I wrote about it. It’s not rocket science.

        It’s not like we read through the tips that are submitted each day and then say “Well, this is the best story, but screw that, I’ll just pick one at random.” Err… I shouldn’t say “we”, I don’t know how other authors select their stories. I’m pretty picky and go through them all, choosing the best ones I feel I have good enough grasp of to cover.

  8. Keep in mind one practical aspect of this gadget. People who work in construction or who’re doing a major home remodel often have older batteries that aren’t useful for their original purpose. Tools demand a lot of a battery. One that’s down to half capacity become a nuisance, running out of power too quickly.

    This device lets your repurpose those batteries for less demanding applications. You get maybe two years use out of a battery for construction and perhaps another two for ‘dark and stormy night’ lighting backup. I do the same with AA and AAA batteries. When they’re no longer useful in high-demand devices such as flashlights, I move them into low-demand devices such as LCD clock/temperature/humidity displays.

    Alas, this Hack-a-day project falls short where many others do. The idea is a good one, but many of those who’d benefit from it lack the time or skills to hack up one for themselves. Some business-savvy entrepreneur needs to commercialize the product or perhaps even persuade companies such as Ryoai to sell them as part of their product line alongside chargers. Running power cords all over can be a hassle. Workers on construction sites might like an 18-volt tool battery to 12-volt or 110v. AC converter to power their radios or cell-phone chargers.

  9. So I have multiple comments about this post. I’ll post the useful one first so if you don’t want to read the rest you don’t have too. I’m building a titanium anodizer, which for those of you who do not know what it really is, it’s a beefed up boost converter. Instead of go the route in which this guy did, I am building mine from scratch. (Which really isn’t a hack and someone will probably give a dumb remark about that, or maybe not because I’m calling you out on it) but I just used two power MOSFETs with PWM from our friend the atmega328p and have it going to a comparator to step-up the voltage to the MOSFET. Then I have a feedback to an ADC on the 328p which I can use the to regulate the PWM. The reason I’m saying this is because you can do this same setup with relative ease and have more functionality to it. (I have an LCD display for actual voltage and desired voltage and safety functions programmed in…I’m building it for my schools art department). I do have to say that this guys doing is more of a hack then mine is…same concept, but his is probably, by far, a lot easier design. So for you who find his too basic build one that is more like mine and for those who find his to be a welcoming challenge, then do his. So a suggestion to hackaday is to place a rating on your posts on the level of difficulty, so you don’t have these a-holes complaining.( you’d probably still have them complain. Complainers are just going to do that). I do agree with the editing issue, though. If you are going to get paid to do a job then you should do it well….anyway good hack for this guy…the important thing is that he learned stuff.

    1. Just FYI – If you have the option, build it so you can get like, 200V. Since you can’t “unanodize” without chemically etching the oxide layer off, if you slip and pass the target color, you can hit it on the next pass (the color band repeats itself at a higher voltage level).

      1. Thanks for the tip. I have it set to go up to 150v at the moment. I’ll have to discuss that with my prof. He may not want to do that. He thinks I’m already go a little overboard on the design I already have.

          1. Yeah, that was the origional plan that he wanted to do. But for the sake of just building something cooler I got the prof. to go along with a switching power supply. It also cuts down on the weight as well and provides isolation from the 120/60.`

          2. Oh, by all means build the cooler supply you want. But just to discover the voltage range you need, temporarily set up a variac or other existing power supply and mess around with it.

          3. Yeah, that is exactly what we were planning on doing to determine the color ranges. We also wanted to do that to determine the resistance of the titanium/color bath, beginning and finished. The only thing that I’m somewhat worried about is the current drawn from the load in the beginning which we will have to get a better step-up xfmr or have to ramp the voltage up over time until it reaches final voltage.

          4. A limiting resistor should be fine. You probably woudln’t even need a power resistor. Unless you’re dipping parts that are the size of your torso, the anodizing process is complete in a quarter second. There’s a current spike but, a moderate electrolytic to help with the kick and you’re fine.

            Basically, until the titanium/niobium/tantalum/zirconium oxide layer is formed, the metal you’re dipping into the bath (TSP or baking soda + tap water, amounts not even slightly critical) is a dead short. But, like I said, in under a second the process is complete.

            Aluminum anodizing, done with dyes, is completely different and hogs lots of current.

  10. i like the idea. wondering if the inverter wouldn’t take 18v directly. Probably try this myself in a pinch. Maybe I’ll put a Ryobi battery socket on the boiler. Get a few hours of heat per battery.

  11. I have been working on projects like this on and off for years now specifically related to Ryobi’s 18V batteries. They make a great emergency source for power (if used efficiently) and because they also remain in service to power my tools,most are in good condition and usually fully charged. In the event of an extended outage, and I realize I don’t have any charged battery banks around the house, I just need to grab a Ryobi pack and I’m back in business. The 72wh Lithium packs are 6ah @ 12v and makes a decent replacement for sealed-lead acid batteries in some circumstances. I have used the 18v packs to power my TDK 513 sound cube (direct 18v) while outside working in the yard and it’ll run all day. I am honestly surprised Ryobi has not come out with an official 5v charging station employing their batteries considering the 72wh should provide around 14,000mAh at 5v. Somebody want to Kickstart that idea?

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