How to Make a Cordless Tool Corded




About: bicycles, gardening, and other important stuff
First, your burning question: why would anyone want to do this?!
Well, for me there were a couple of reasons:
1. Dead batteries suck! And, when you're running a circular saw, saw-zall, or pretty much anything else constantly, dead batteries happen very frequently.
2. Batteries are not cheap, and they don't charge fast. Even with 5 batteries and 3 chargers, a good-sized project + my questionable competence at most things one can do with power tools often leads to waiting for dead batteries to recharge.
3. More power:) You've overclocked your computer, so why not overclock your power tools?
4. I *think* this'll be a bit more energy-efficient than recharging and discharging batteries... certainly more earth-friendly if you take into account impact of metal used in extra batteries you won't have to buy...

As usual, this is not the safest or most professional of projects. Please don't hurt yourself any more than you'd like to:-)

Here's a video:

Step 1: Gather Your Supplies

You'll need:
-cordless tool(s) to make work corded, complete with charger. I used these.
-an old ac power cord that you don't mind ruining
-an extension cord to run between charger and tool
-foam or something else that's nonconductive, flexible, and easy to work with. i used a dried-out piece of the nastiness that is known as great stuff.
-your favorite roll of duct tape
-aluminum foil or other conductive, flexible material

And, it'd make life easier to have:
-something to make the corded adaptor easy to remove from the tool. I used these, and they worked well.
-wire strippers
-pocket knife, leatherman, or other way of cutting and turning screws
-a pack of spare batteries, like these.

I'm sure you can do this with other tools; I happened to have a set of the cheap-but-usable Ryobi stuff, so that's what I went with.

Step 2: Modify (or Build) the Battery Connector

If your tool set has a carrying accessory that snaps into the battery connector like mine did, this step's easy: just cut a hole through the carrying accessory that's slightly bigger than the cord you want to run through here. If this doesn't exist for your tool, create one out of your favorite nonconductive substance or (carefully) take apart a battery and just use the shell.

I got annoyed by the nylon carrying loop thing, so I cut that off too.

Step 3: Attach the Cord

Next, you'll need to run the end of your AC cord through the hole you just cut in the accessory connector:
1. Push, pull and otherwise force the wire through, with the AC prongs facing the bottom (you'll connect these to the extension cord when you want to run power to the tool). Needlenose pliers were helpful for me on this step.
2. Attach thin strips of duct tape around the cord, right by where the cord enters the accessory connector.
3. Strip the ends of the extension cord's wire.

Step 4: Carve the Connecting Thingie

The tool's leads to connect to the battery are not at the base of the battery connector: they're on the sides, near the top. So, you need something to get your wires up into the tool and touching the tool's battery leads.

I used a dried chunk of Great Stuff, the spray foam that is a pain to remove from pretty much any surface:
1. carve foam chunk such that, when it rests on the accessory connector, it's approximately the same size as the battery pack's lead
2. carve an 'arch' through which the 2 wires can lead to the terminals
3. if the carved foam is too tall, drim down to approximately same height as battery pack
4. run one wire to each side of the arch
5. attach aluminum foil to each wire and wrap the whole thing in duct tape. be sure you leave foil exposed, so that the tools leads can contact the foil on both sides. if (when) the connector won't slide onto your tool, trim off all the extra duct tape you used:)

Step 5: Modify (or Build) the Charger

You'll need something for the other end of the DC-carrying extension cord to attach to, and this something will be an AC outlet connected to the charger.

Easy way to do this: run some aluminum foil or a wire to the point of connection between battery leads and charger. On most modern chargers, you'll need to put a discharged battery in the charger before you can provide any current to the tool. I tried this, and my corded adaptor would stop working whenever the battery became fully charged.

The way I did this: connect to the battery charging terminals, but from inside the charger. This lets me use the charger to recharge a battery while also powering a tool via the corded adaptor, and I don't have anything interfering with the charger connection to the battery. I meaured >10 amps output when a battery was not inserted using this method, so be careful: hooking a tool up to this might turn it / the charger / you into a charred chunk

Yes, both of the aforementioned methods probably increase the likelihood of battery or tool explosions or other nastiness occurring.

Smartest way to do this: measure the current and voltage provided by your battery and create an ac-dc adaptor that'll output this.

Step 6: Rock And/or Roll, Without Recharging!

Check the voltage/amperage output with your multimeter to make sure it's within a range of the intended input to the tool for you to feel safe (note: for me this required keeping a batter recharging while using the corded adaptor. if the battery finishes recharging while i have this connected, that *might* be a problem...), connect an extension cord between dc-carrying ac outlet attached to charger, and plug the other end into your corded cordless adaptor. turn your newly-corded tool on, and rock and roll! if it doesn't work, i'd bet you w/ 10 to 1 odds that your aluminum foil attached to the carved connector thingie isn't making contact with the leads on the tool. Duct tape and foil away until you've got it right, and happy tooling:)



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    37 Discussions


    1 year ago

    first step is smoke or inject at least .25g methamphetamine, if your going to eat it, gonna have to wait another 10 minutes before you can get started..

    step two take your shirt off

    step three is this video..

    1 reply

    Reply 1 year ago

    LOL. The first thing entering the back of my mind when I saw the first photo was this. Your comment topped it off.


    3 years ago

    Just a thought for people that upgraded to li-po batteries, you could pull the tranformer out of the charger and put it in one of the old ni-cad batteries and use that

    There are cordless power tools that charge quickly enough for one to not need 5 batteries. My Makita tools recharge in 30 minutes and I get by just fine using two batteries.


    4 years ago on Introduction

    how did dewalt get a 24 V 350 watt supply in that 24 v battery case? was their a brick on floor to run the dummy battery case ive a rigid max HC nimh battery its like 5x3x2.3 can i get a supply in it?


    5 years ago on Introduction

    Maybe you'll need a voltmeter to figure out what each of the different leads are. I wouldn't use a larger voltage battery, you might get away with 12V without burning it out instantly, but you'll definitely shorten the life. Have you thought about re-celling the battery? Hollow out the battery more


    8 years ago on Introduction

    I watched the first five minutes of your video...figured I had the overall point . Made my own yea..don't plug this directly into the wall....after the smoke had cleared , I watched the rest of your video.


    Seriously, next time cannibalize an old battery or even get a ghetto cheap generic replacement to cannibalize.

    I know it doesn't take long for those batteries to go bad in the first place. On another note, seriously, tin foil, great stuff and duct tape? Dude, you're going to wind up with the ultimate multi-tool: all-in-one flame thrower, arc welder, power saw.

    Overall though, very awesome you rigged that up. I just hope you own a fire extinguisher ^_^


    9 years ago on Introduction

     Talk about living on the edge...well at least he is trying stuff a lot of us have been wondering if it is possible. Thanks for the instructable man!


    9 years ago on Introduction

    I think he's cute, and if wants to do something dangerous shirtless without tatoos and paunch, I'll certainly watch. However, I hestitate to speculate on the pants situation....


    10 years ago on Introduction

    First, Get a shirt. Second, just you wait til someone comes along to use your tool and they plug it into a real wall outlet. that will make your day. And you should really cover up those electrical connections and use a proper outlet box. I also agree with 12V and say, replace the batteries with higher capacity ones. Also, need better pictures, I think my ole camera would outdo that cellphone camera.


    10 years ago on Introduction

    1) Use a thicker cable, btw. Those cords are meant to carry prolly no more than 4 amps. At 120AC, 4 amps is a lot. At 12V or w/e ur running, 4A is nothing. Oh, and throw away the tinfoil crap and start over. 2) Stick a battery in the charger while using your saw. Sure, we all say your saw running just peachy for 3/4 of a second under no load. But have you tried to actually cut anything, yet? I have a feeling your saw will stall and the motor and/or charger will go up in smoke. Peak current output of a NiMh battery is higher than what even a large power supply can provide. So make sure you keep a charged battery in the charger while you're doing this. The battery will be there to prevent a problem when the peak load exceeds the charger's output.

    1 reply

    Reply 10 years ago on Introduction

    if you change the cells in the battery to 3800mah ni-mh sub-c cells it will last up to 4 times longer! battery voltage no.cells neded 7.2 6 9.6 8 12 10 14.4 12 18 15 24 20 30 25 why not change the old 1200s for 3000+? the table shows how many cells to buy to replace the 1200s


    10 years ago on Introduction

    That looks dangerous, and you can fry your charger by overloading it with the saw. BTW: I converted my cordless drill in a more safer manner by gutting a dead battery pack, and wiring a car plug to it's terminals (lot more versatile for power supplies for any use).

    this seems like a good idea and dewalt did have a 24volt version of this (minus the duct tape ,fire/death trap and just plain stupidity)but OH MY GOD WHAT THE HELL ARE YOU PLAYING AT YOU FOOL? duct tape? alu foil? is this a kids program making a space suit? you're not going to open that charger while it's still conected are you? OH YES YOUR ARE! why didn't you just use the top of one of the batteries?


    10 years ago on Introduction

    keep in mind you probably arent insured if you mess with the power supply of tools @ work


    11 years ago on Introduction

    There is a reason why cordless power tools are not manufactured for corded and cordless use. Cordless power tools and corded power tools use different types of motors. The reason they don't make a corded attachments for current cordless tools is because the transformers required must handle a lot of current and are very expensive, most times more expensive than buying an entirely new tool. Lets give an example, if you had cordless power tool a that was 12V, lets say it sank 2 amps... well then the tool would use 24 watts(V*I) of electrical power. Now lets say we design a different tool using a 120V ac motor and we want the same power, well now we only need (W/V) 0.2 amps. A lot less current, which means a lot less heat in the transformer. Now I can't say I design power tools but I have done a bit of research when trying to build my own version of this project in the past. A few safety recommendations. Don't use duct tape on electrical work, use electrical tape, its not expensive it is meant for that purpose. Duct tape isn't even used on ducts, so it gives you an impression to how reliable it really is. Don't use a wimpy 2 prong cord to handle 24 amps, they barely handle 2 amps without blowing up. Also add a fuse and a shirt. :-P