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
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
Small flat-blade screwdriver
Step 3: Modify Terminal Connectors
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
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!
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!