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second thoughts on battery rebuilds

July 12, 2007

A long while back I was pondering rebuilding a cordless drill battery pack to revive the powerless, yet otherwise entirely functional, tool. I took one pack in to The Source to inquire about their price to rebuild the battery, to which they replied $80 for a single 12V battery pack. That is equivalent to purchasing a new one, and I know that there is plenty of profit built in to that figure. So I figured I’d give rebuilding the battery a crack at it myself. To that end, I’ve even acquired another drill with dead batteries for twice the fun.

Tonight, however, it dawned on me that I am once again just being more sustainable; even if I rebuild the battery packs myself instead of purchasing entirely new batteries (or an entirely new drill for that matter), I’m still going to be using batteries which will eventually die. Yes, I’m reducing the amount of garbage I’m producing, but could I do better? I think I can.

Why are drills cordless? Or any power tool for that matter? Convenience. It’s simply easier to bring a tool places where it doesn’t need a cord – at least, until the battery runs low. What are the trade-offs? Instead of hoisting just a drill plus its cord, you get to hoist the drill plus its battery, arguably much heavier than what a cord would burden you with. You get a limited amount of run time, depending on how charged the battery is, and at what stage it is in its charge life cycle. Are these tradeoffs worthwhile? If you consider the battery a consumable – which is what it is, as it has a finite life – and compare that to a corded drill, the benefits become more dubious. So now I’m wondering if I really do want to rebuild my battery packs. I think I may cord my drills instead.

Instead of having a battery, I picture tethering these formerly-cordless tools to a power cord and an AC/DC converter. You can plug in to household current, the converter will supply you with your needed 12V (or 14.4V, or 18V, or whatever your tool needs), and as long as you have a long enough extension cord to reach a plug, you’ve got a tool that will work as long as you can. I think the idea has merit.

At this point the only big question is the AC/DC converter; how do I find one with the correct input and output voltages? How do I integrate it with the drill? Could I even put it in the spot where the batteries would have gone, or does it need to be separate? This is what I will be researching next.

As much as rebuilding a battery pack is a good idea (over replacing the battery pack or the entire tool), I think a better solution will come. Stay tuned.

If anyone has any information about AC/DC converters in the 120VAC to 12-18VDC range, please contact me.

11 Comments leave one →
  1. Jerry permalink
    July 13, 2007 12:16 am

    Uhhhh, wouldn’t it be easier to sell the cordless drills and buy corded ones instead? (8-) Sure, you’ll take a hit between your sale price and the price of a new drill, but, it’ll still be cheaper than buying the equipment to convert the cordless ones.

    Of course, this is discounting the ‘fun factor’ of taking power tools apart. (8-)


  2. July 13, 2007 7:59 am

    Another question: What if you need to build something where there *is* no electricity, and your budget doesn’t allow for a generator (ie: because the project is too small, or it’s a big project, but the budget didn’t allow for a generator)

    Also, it’s arguably safer to use cordless tools in some situations, as the cords might introduce a work hazard to the site.

    I prefer having a corded *and* a cordless drill because the cordless ones typically come with a clutch, and corded ones not.

    I think the most sustainable strategy is simply to use tools that require no electricity, rather than hack power tools to use alternate forms of electricity. Or do what Jerry said and just buy yourself a corded drill already. 🙂

  3. July 13, 2007 7:36 pm

    The point of the exercise is to NOT default into consumer mode, “I can buy my way out of my problems”. It also misses the point, in that I have a prefectly functional drill, all it requires is power to work. The question I am trying to answer is how can I make my drill work again using the least amount of resources possible? I believe cording them is the answer (so far).

    I’m not saying there isn’t a place for cordless drills, but I am saying I likely do not need the convenience. If you’re heading to where there is no electricity, just ask your local Mennonite for a hand drill.

    By converting my cordless drills to having a cord, I get to keep the clutch and multi-speed features that corded drills do not.

    Yes, you’re correct – manually-powered tools are the most sustainable. I don’t think that people are ready to give up that much convenience yet… they may be willing to put a cord on their cordless, but probably aren’t willing to put a deck together with a screwdriver just yet. 😉

  4. Jerry permalink
    July 14, 2007 12:26 am

    The question I am trying to answer is how can I make my drill work again using the least amount of resources possible?

    *nod* Just don’t forget that time is also a resource. (8-)

    Good luck!


  5. Kyle permalink
    July 19, 2007 12:42 pm

    I am also trying to develop this idea. I have found the same problem; just when the job is about done the battery runs out…..

    The problem I am having is finding a transformer with a big enough amperage to power the tool.

    Any more luck for yourself?

  6. August 15, 2007 9:26 am

    Thanks for the link, Das. However, if you read through that carefully (I had already seen it, as it turns out) the set-up being described isn’t truly a batteryless operation. It would be better described as “continual charging during use”. It still relies on the battery, but it’s being charged all the time.

    Kyle, I’ve had no such luck yet. I’m still waiting to have the time to dismantle my drill and try to figure out how much current it will need.

  7. Joe permalink
    March 12, 2008 2:19 pm

    For years I’ve wished the coordless power tool companies would make a corded AC adaptor pack that would fit in place of the battery. that way you could save battery life for when you need a cordless drill, and use it corded when you don’t or battery packs won’t last long enough.

  8. Philip permalink
    July 1, 2010 12:30 pm

    Check this out… I have the craftsman ultimate cordless tool set with 18 different tools that run on 19.2 volt batteries. Anyhow, you could see the advantage of having the option of a cord or cordless. That would be ideal for my situation. On set of tools, corded or cordless. So, here is a guy who made one out of discarded junk. I plan to do the same.

    Tell me if it works for you.

  9. Dave permalink
    September 10, 2010 8:43 am

    Does anyone know much about transformers? Has anyone here tried this same solution to the AC to DC power tool conversion? Cleghorn (above post) uses a microwave transformer and a bridge rectifier, but I don’t know much about these products. Is the microwave transformer the right input (120V) and output (18V) and if not, is there a way to change those? Anyone know of a good website that explains these things more? Thanks for any help and feedback from anyone who’s tried this.

  10. October 22, 2011 1:31 am

    I’m sure you’ve already solved this, but I’ve been converting cordless drills to cordless for years. Essentially you just dump the drill battery, solder a length of flexible cable to the terminals inside the drill, and attach either alligator clips or a cigarette lighter plug to the other end. My conversion of choice is the early 1990s vintage Ryobi 7.2v, because it has a trouble-free keyed chuck and a strong gearbox (made with actual metal gears). Old 7.2v or 9.6v Makita drills will work too.

    No, I haven’t yet had a 7.2V drill catch fire while being run on 12V.

    For the people who pooh-pooh the idea, it’s a very useful tool if you’re living off-grid, or if you don’t want to haul a generator into range of a distant job. Car batteries that won’t supply enough current to crank a vehicle will usually still power one of these drills just as well as the “factory” NiCd or NiMh battery, and also self-discharge at a much lower rate.

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