This Instructable will show you how to assemble an adapter to use a Bosch 18V Lithium Ion battery on a Porter Cable power tool.
I have two Porter Cable power tools, a drill and an impact driver. When the original 18 volt NiCad battery packs fizzled out, I decided to look for Lithium batteries to replace them. The Porter Cable batteries are ridiculously expensive compared to the Bosch batteries. I could get two Bosch 18V Lithium 1.5 amp hour batteries for less ($60 delivered) than the cost of just one Porter Cable ($80). I ordered up two Bosch batteries, thinking I would simply adapt the cells into the original PC battery pack housing. When I looked at the interface differences between the two battery types, it seemed like a good little design/build project for CAD and 3D printing. The adapter was designed in Autodesk 123D Design. I'm going to work on redesigning in Fusion 360 when I have time. STL files area available for download.
Step 1: Start With the Original Battery Pack
You'll need to start by opening up the original battery pack to retrieve the plug interface (assembly) from the pack.
Step 2: This Is What You'll Need From the Original Pack
Once you have opened up the housing, clip the wires from the plug interface for use later on.
Step 3: The 3D Printed Parts
The parts must be printed out of ABS because they will be glued together later on. The lower section fits the Bosch battery. It has a 1mm recessed section that outlines where the upper section will be glued in place after soldering in the plug interface and electrical contacts for the Bosch battery. The latch is designed to be actuated by the spring loaded Bosch latch, through the upper section with the assistance of a light weight ball point pen spring to release the latch on the upper section where it interfaces with the Porter Cable tool.
Step 4: Preparing the Plug Assembly
The plug assembly is fitted in place as shown. Relieve the areas where the wires will need to be connected with a Dremel tool. View additional steps if this doesn't make sense.
Step 5: Battery Contacts - Solder and Assembly
Use standard spade connectors (14ga) and solder wire leads to the connectors. Thread the wires through the hols and use needle nose pliers to install the spade connectors as shown. The printed part should hole them securely enough to interface with the Bosch battery easily.
Step 6: Soldering the Plug Assembly in Place
Place the plug assembly in position to measure where to trim the wires to be soldered in the following steps. Remove the casing from the wires and bend them down so they are just above the lower section as shown in the second image. Tin/solder both the wires and the plug in the areas where the wires will be soldered.
The solder connections should allow the plug assembly to sit down flush on the lower section, once complete.
Step 7: Installing the Latch and Preparing for ABS Glue
Find a cheap ball point pen to steal the spring from it for use in the latch release mechanism. You may need to chase the hole first before installing the spring.
Step 8: Glue and Clamp
Use a small brush to wet the areas that will be fused together between the upper and lower sections. Use caution around the area of the latch to make sure you don't slop any glue into the channel where the latch will need to be free to move.
Drying time for ABS glue is pretty quick. You should be able to use the adapter as soon as an hour after gluing if kept at room temperature to dry. The glue is acetone based so keep in a well ventilated area for drying.
Enjoy your new adapter and inexpensive lithium battery pack!