- 1 broken drill
- 1 matching wall wart
- Lineman pliers in lieu of a crimp tool
- Wire connectors
- Spare wire
- Pocket knife
IMPORTANT: This is a DC circuit. DO NOT CROSS THE LEADS. If you're not sure what you're doing, get someone experienced in DC circuitry to help you.
Step 1: Taking Apart the Drill
Once you get the drill apart, you can see it's an elegantly simple device: a motor, a relay and transistor to control it, a power source and a switch. The power plug is wired directly into the connector for the battery.
Step 2: Wiring
If you're unlucky like me, start by removing the connector, making sure to leave enough wire on the connector to hook the multimeter lead to. Set your multimeter to continuity mode, then clip one end to one of the wires coming off the connector. take the other end and touch it to the outer barrel of the connector, then the inner sleeve to determine which is the contact point for that wire. Turns out on my drill, the wire with the stripe was the positive lead... good thing I checked!
Next, check the wires connecting to the plug on the drill - on mine, the red wire running to the center pin was the positive lead, and the barrel was the negative. So, for me that means the wire on the adapter with the stripe needed to connect to the red wire in the drill.
I wanted to make sure I could charge and use the drill safely, so I wanted to A) use covered connectors, and B) make sure it was impossible to cross them, just in case someone other than myself needed to charge it. I used a red barrel connector for the positive lead, and the blue spade connector for the negative.
There wasn't enough wire in the drill assembly to be able to have the connectors fit, so I used a bit of spare wire and a couple crimp connectors to extend the plugs outside the drill casing.
Step 3: Reassembly and Final Thoughts
Some things I learned through this project:
- Make sure the connectors you use are good quality and the right size for your project. Also, invest in a quality crimp tool if you haven't already.
- Use shielded connectors to minimize the risk of a short circuit. Since the connectors I used are only shielded on the drill side, I have to make sure I unplug the wall wart before disconnecting it from the drill. Small price to pay for not zapping my wrist every time I go to build something.