Tired of Dead Batteries in Your Cordless Tools? Me Too! So Let's Hack Away!!





Introduction: Tired of Dead Batteries in Your Cordless Tools? Me Too! So Let's Hack Away!!

ok this is my 1st instructable so please be kind.
Are you like me when it comes to cordless tools? I get so frustrated with half finished projects and hours of wait time while those "convenient" cordless tools charge. so, i wanted to add wall power to them but, the key for me was to achieve this and not make a permanent mod to the tool itself,. now the real question is.. HOW result do i get that result? surprisingly it's really simple, minimal soldering required and again not a permanent modification to the tool. the best part is that i can change from tool to tool for flexibility, i can still use battery packs when an outlet isn't available and it cost me no money.  OH and it only took about 30 minutes. OK let's get hacking!!

Step 1: Tools and Supplies

1) cordless tool(s).  I had a 24v firestorm drill/ jig saw/ reciprocating saw combo i had rescued from someones curbside trash (YaY free!!)
2) suitable voltage converter w/ power cord (IE laptop charger or such), works best if it also is small enough to fit inside the old battery pack (this one was in with a bunch of electronics i rescued from a dumpster (YaY free again!! sensing a theme yet?) You could build your own if you have that skill, or a wall wart will work fine too, i didn't have a wall wart capable of the 24v needed for these tools.
3) 22-24 AWG wire 
4) soldering iron w/solder
5)   shrink tubes, sandpaper or small files, pliers, screwdrivers, a dremel is very handy, hot glue gun and glue (or if you're like me and don't have one...improvise) 
6) and MOST IMPORTANT....a little common sense

Step 2: Dismantle Battery Pack

simple, easy and we should all have the basic idea how and what to do here...if not, STOP now!! check the photos for a couple tips though,

Step 3: Dispose Of/ Recycle Old Battery Cells

i felt this was imptortant enough to be addressed as an actual step. NiCD batteries must be disposed of properly, preferably taken to the recycle plant. black & decker were kind enough to provide a 1-800 number for this purpose.

Step 4: Prepping for Assembly

i really like the work to go smooth so i prefer to lay out everything orderly, strip wire ends, prep surfaces for solder, etc. this is also the perfect opportunity to determine how to fit the converter into the original battery pack box (this is why i opened up the battery 1st then did lay out), how much wire will be needed and placement of the through hole for power cord. i find it also helps in ensuring i have all the tools/ supplies i need. more than once i've laid out everything only to find i was missing that one crucial tool to complete the task at hand better now than halfway through the project.

Step 5: Connecting Everything

1st you should already identified + and - inputs on battery pack and outputs on converter.

I choose to solder the leads from the battery pack 1st, whether thats the best approach or not is a matter of opinion i think. though i will say that it's best to remove (one at a time) the metal connection points from the pack before soldering as that will keep you from melting the plastic housing and mounting spots rending that pack case unusable as the contact points will not line up correctly.

next up is soldering the + and - wires to the converter. mine worked out perfect as it was surface mounted rather than trying to solder wires together or fit into some tight space on the board.

Step 6: Pack It in and Close It Up

place the converter into the bottom of the battery packs case, line up the plug with the hole cut during layout. add spacers as needed to secure the converter in place. close it up, ensuring to put the spring and latch in place or it won't lock into the tool properly.

Step 7: And We Are Done! Time to Enjoy

last thing to do is test it out. so, plug in the pack to the tool then plug into an outlet and voila! we have a working tool again...no more dead batteries either. now i have a circular saw, jig saw, sawzall, and drill all capable of both battery and wall outlet power, one mod, 4 tools....
final note; while it is possible and maybe even perfectly safe, i still do NOT recommend plugging into wall outlet before connecting the battery pack case to the drill, saw, or whatever tool chosen. 2 seconds of safety VS possible electric shock or death...your choice! either way i am not liable or responsible for any damage, injury, death, fried electronics, or burned down houses.  you undertake this instructible at  your own risk and peril 

hope everybody enjoys this 'ible. thoughts and questions are welcome.

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    I have to say for those a little bit electronic component wavy is way better to build your own power supply for a toollike this. Unlike the tools sold as AC wall powered which actually run fine with 48 v of DC power from car batteries, the tools
    Sold as D.C. Will not happily accept AC power because they are in fact DC motors, so you can't just plu g them in the wal and have them work.

    Here are the stages of power supply convertor you must make for this to work right. First the AC mains power must enter into a step Down transformer which will ratio the voltage down and the current up by the same factor so if it's a 2:1 step down your wall power changes from 120VAC to 60VAc. And the available current steps up to that times more current that it would produce beforeThat is too high to work with so I know your transformer will more likely be a 6:1 step down transformer so that the voltage come so out ~20V AC on the other end. Then you only need to run the lower voltage AC throuh a bridge rectifier (a set of four diodes typically all connected to each other at one of their ends (look up diagram for this) and lastly add a couple large capacitors in parallel with the output to smooth out the AC humps or "ripple" noise and make the power stable and cleaner which also drops the voltage down by a factor of about 30% putting you in the sweet spot for a D.C. Unit voltage to the drill.

    I wonder how well this is going to work. A while back, I investigated what was needed to do a mod like this. The big problem was that power tools require a TON of amps, which power supplies cannot provide. The alternative was to build a massive (meaning, *heavy* and *expensive*) power supply, or use something like an external battery (car battery would work, but 12v vs 18v is a nono).

    can you share what power converter you used, make and model number.

    i've collected a few battery powered tools over the years and some don't have the charger anymore...this is a great way to restore them! thanks

    What do you do if you don't have the batterie pack?

    Good plan! I have a question, though... I tried the same trick using a laptop power supply (19.5 V) to my 18 V Ryobi One tools. Alas, when the tool starts the current required is too high and then the power supply simply shuts down. I measured (using the batteries) currents well above 15 A when tools start and I do not know of any compact and inexpensive power supply capable of that. What was your experience?

    1 reply

    I had the same experience with Ryobis. Not entierly sure what the issue was.

    Thanks I'm going to do this for my ryobi set the saw just eats up the 18v battery's

    1 reply

    I tried this with Ryobi and didn't have good results. Did you get it to work?

    I tried this with a set of Ryobis and it resulted in a super slow low power tool. Do you have any suggestions?

    You're a genius

    Hey, I have that same tool combo, my dad gave it to me when he upgraded his set, and my batteries are ancient and don't hold a charge for long. Can you point me to a suitable voltage converter with power cord?

    1 reply

    Do you think this would work?


    so if I use this? http://www.amazon.com/Adapter-Kawasaki-SH-DC240400-690074-Supply-Charger/dp/B00CM0VM12 i can do this with my craftsman 19.2v drill?

    thanks to everyone for your kind comments' I had some issues signing in lately so if I have missed sending a response to any questions I will try to get caught up. just to clear some stuff up: the batteries were removed and replaced with a converter, amps were checked and double checked then I had a friend check a 3rd time, same goes for watts and volts, a multimeter is your friend here. also for positive and negative pay close attention to how the batteries are connected before removing them, this one actually had it marked pretty clear but I did check with the multimeter as well just to be safe. oh and an update...I finally got the glue sticks for my glue gun, no more messy improv stuff there.

    is there a way to determine which one is the positive and which one is the negative ?

    Thx for this project - exactly what I needed :)

    1 reply

    best way to tell is to look on the battery, use a Multi/Volt Meter or a Test light


    P.S. , Goodwill always has awsome adapters and electronic parts for cheep. I'm sure I can find exactly what I need ther.


    I was so excited to finally see this project being done! I have an expensive drill and three dead batteries. Replacements were over 40 dollars each! I will post progress of the completed project when it is done'

    This is very helpful. I had never thought this through. Thank you!