Fixing Good Thrift-store Powertools on the Cheap




About: I'm a DIY ideas man. I constantly strive to create my own products including tools. I'm actually a master of misusing/reusing things and getting better results. I love new ideas and manifesting them into rea...

Power tools can be expensive... The thrift store can be cheap... With a bit of DIY magic and effort we can get the best of both worlds.

First thing you will need to do is make a Sealed battery box 12v/24v with a switch. This instructable uses that battery for power. If you want to review this to get ideas for your mod then feel free to skip that but if you do everything in all the steps you will need the battery or one with similar plugs.

Materials needed for this (Tools not included in list):

  • Plugs... male & female connectors. (Find/Buy it here)
  • Standard compute power cord (Pcord 18/3 - These are everywhere you'll find one for sure)
  • Zip tie
  • Some spare electrical tape

Now that you have all the supplies let's begin.

Step 1: It's Usually the Battery, Let's Crack It Open.

It usually is just the batteries. Be careful! Even though these crappy batteries can't turn a drill they may still have enough power to shock you!

This battery has T-10 screws. Take them out and the battery housing comes apart in 2 pieces. Inside you find the battery bank and the copper connectors resting on top. The connector has little plastic legs that fit snug between the batteries keeping them in place. Because of this we're going to end up keeping 4 of the batteries in there to make things easy. We are not going to be connecting these batteries to power they're just part of the structure now.

Step 2: Gutting the Battery

Inspection reveals that 2 of the 3 copper leads are spot welded to the battery ends. No problem, we can cut the copper since we only need it to reside on the plastic. I also recommend using pliers to remove the copper welded to the batteries after you cut. If you don't have a dremmel then you can use a good pair of wire cutters. Cheap ones just aren't good enough.

After that you will need to remove all but the 4 batteries holding up the plastic and copper connector. I recommend putting a few wraps of electrical tape around them to prevent accidental shock. Once taped up the little legs that keep the plastic piece in place can just be pushed through the tape for a sung fit.

Step 3: Prepare the Cable

Grab your average power cord and cut both ends off it. We're not going to be using them. Strip the wire ends on both ends. There are 3 in this one but we only need 2. It's your choice on which ones you want to use just make sure you remember which is positive and which is negative. I prefer the old standard of Black (-) and White (+). The pins in this instructable can be crimped or soldered or both. I prefer solder and crimp but it's really up to you.

Step 4: Apply Power Cord to Empty Battery Housing

Next we need to make a hold for the other end of the power cord to fit through. Use a single zip tie to keep the cable from wanting to come all the way our and stress the soldered wires. For this battery the copper pins were labeled positive and negative so it required no testing with the volt meter. Other batteries may require more testing if they're not labeled like this one.

Figure out the best way to solder and place the cable. This plastic piece came with some great grooves under it that fit these wires perfectly.

Step 5: Seal It Back Up and Good to Go!

After this you can close the battery housing and apply the screws in the proper place. That pretty much covers it. You can see that it fits the 12v/24v battery perfectly. This set was originally 18v so taking it up to 24v is no porblem for it and it gives it great speed. Write in the comments if you have any questions or suggestions. Thanks for reading!



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    10 Discussions


    4 years ago on Introduction

    Since you do not need the battieres...could you just remove them and fill the void with something lighter?

    3 replies

    Reply 4 years ago on Introduction

    Most of these tools are designed to have the weight of the battery pack below your hand to ballance the weight of the motor above. If you remove the batteries you make the tool very hard to handle.

    It could but I find that a good firm grip on the tool will keep it from jumping out of your hands. The only one that would be an issue is the drill and holding on to it really well does the trick.

    Certainly could although empty space is lighter than anything I could fill the void with. I could have fabricated something to fit in place of the 4 batteries I kept but that would just add extra steps and 4 batteries in there is not a heavy load. I did this to another drill battery and because of the design I was able to remove all the batteries and use epoxy to keep everything together. It really all depends on how much work you want to put into it and the design of the battery pack.


    4 years ago on Introduction

    Yeah that is why folks get rid of cordless tools. The batteries go, and they figure it isn't worth replacing them. So they ditch the old tools, and take that money they might have spent on batteries and just upgrade to better tools. I can't say I blame them. There are some sweet cordless tools out today.

    1 reply

    I'm partial to DeWalt power tools. I like their designs and quality. This powertool set cost a total of $45 when you round up to donate to the Good Will. Can't get good DeWalt tools for that cheap.


    4 years ago

    You can use rechargeable cells designed for rc cars to rebuild battery packs. Just don't mix battery types.

    1 reply

    I could have rebuilt the pack with RC batteries maybe a good kind like NiMh or LiFePo. I would have to go buy new cells to put into there and make sure their dimensions are right. I already had this battery box so it makes sense to use it. In the ible for the battery box I showed it using my SLA battreies but I have a couple different sets that I can put into the box in minutes so it's an advantage for me to use it. Never mix battery types like LiFePo & SLA and the other thing to watch out for is combining batteries rated at different Ah even if they are the same chemistry. Actually, mixing batteries of different chemical makeup, voltage and amperage is never a good idea. It doesn't always end up in bad results but I don't think it's worth risking a battery exploding near you.