Franken-Saw (a.k.a. How to Use a DeWalt Battery With a Bosch Reciprocating Saw)

I discovered a Bosch 18v reciprocating saw sitting on top of someones trash can. It didn't have a battery, but that didn't deter me. I have several DeWalt 18v batteries for my drills and I knew there had to be a way to use them. So I brought it into my workshop and began playing.

I disassembled the saw and traced the wiring to figure out which terminal was positive and which was negative. Once I determined which was which, I ran some wire from the DeWalt battery to the saw terminals to make sure that it operated. It did. Now to make it usable.

Step 1: Materials

Bosch 18v reciprocating saw, drill, or other tool
DeWalt 18v Battery
4 - female disconnect crimp-on connectors (16 AWG)
1 - 5 inch length electrical wire (16 AWG)
1 - zip-tie

Step 2: Tools

Bench vise
Long-nose pliers
Wire strippers
Crimp tool
Small flat-blade screwdriver
Ruler
Electrical tape

Step 3: Modify Terminal Connectors

The female disconnect terminal connectors must be modified to fit the saw and the battery. The terminals for the saw need to be flattened, and the terminals for the battery must be opened up.

I flattened the 2 terminals for the saw using a bench vise. Just put the connector in the vise and tighten until it's flattened.

The other 2 terminals were opened up using a small flat-blade screwdriver.They must be opened up just enough for a snug fit on the DeWalt battery terminal. If you open it up too much, use your pliers to adjust it to the right size.

Step 4: Prepare Cable

Cut your power cord to about 5 inches long. It doesn't have to be exact, you just want it long enough to easily connect the terminals and fold the excess into the battery compartment.

Separate the ends of the cable and strip back about 1/4".

Place the crimp-on connectors on the cable. Put the 2 flattened connectors on one end, and the opened connectors on the opposite end.

place the zip-tie about 1" down from the base of the flat blade connectors to keep tha cable from splitting.

Step 5: Bring It to Life!

Now that the cable is made, let's put it all together and see if we can bring the saw to life.

The flattened terminals will slide into the battery terminals on the saw. It may take a few tries and maybe long nose pliers can help with this step. Now fold some excess wire into the void and grab the battery.

Now take the negative wire and connect it to the negative terminal on the battery. Do the same with the positive terminal.

Feed the rest of the wire into the void and press the battery into place. Get some electrical tape and wrap it around the battery as shown.

Have fun cutting things with your new Franken-saw!