I was able to find a free old battery powered drill and a free laptop battery.

Please see the drill in action in the video.

I needed another battery drill so I was able to use the Lithium Ion cells from the laptop battery to give the drill new life. Now it lasts way longer and is more powerful then when the drill was brand new. This new drill can run for about one hour under heavy load.

There are so many drills with broken batteries that are easy to find for free or very cheap. Also laptop batteries with only one bad cell are very easy to find.

Step 1: Testing the Batteries With the Drill

First remove the old batteries from the drill.

Then remove the wires and check which ones make the drill turn. You may need to solder extra wire so they are long enough.

Now make a battery back with the laptop cells. Please see my instructable on making a battery pack at the link below.

https://www.instructables.com/id/Free-lithium-Ion-B...

For drills that use around 7 volts you want to use battery packs with 2 cells in series (full 8 volts, empty 6 volts). For drills that are closer 10.5 volts 3 cells should be used in series (full 12 volts, empty 9 volts). Three sets should be used in parallel so the current is less than 2C when the drill is under heavy load. I used cells that are 2200mah. So at 1C each cell would supply 2.2 amps. For 3 sets in parallel 1C is 6.6 amps and 2C is 13.2 amps.

Before putting the drill together I connected the battery packs to the drill with an amp meter. I measured about 6 amps under load and 9 amps stale load. This confirmed that three packs in parallel was a good choice.

For longer drill run time more packs can be added in parallel.

Step 2: Attaching the Batteries

So to make this simple I just taped the batteries to the drill. There are many other more permanent ways to attach the batteries. For now I will use it like this.

I connected all the positive wires from the batteries packs together and then all the negative wire together. I soldered all the negative wires to the negative wire from the drill. I then soldered all the positive wires to the drill positive.

I taped over all the packs to make sure they are secure.

Step 3: Using the Drill

The drill works really well to drill holes or drive in screws. It works in both directions.

My drill works better to drive screws as it is slower and has lots of torque.

Step 4: Charging the Batteries

Charging the batteries is very easy but can be dangerous.

I just connect my transformer (12V 1A) to the wires on the drill. My transform has a high voltage and lower amperage limit then was needed. I needed to connect 6 small alligator clips together to provide resistant to lower the amperage. When charging the batteries the amperage was at about .8 amps.

It is important to find the right transformer to charge the batteries. Also set an alarm and keep checking the battery voltage. It should not go over 4V or maximum 4.2V per cell.

Then using the drill it is important to check the voltage often to ensure it doesn't go below 3V per cell. For my drill as the pack voltage goes below 6 volts (3 volts per cell) the power will show a noticeable drop.

Also with this open design it is easy to check each cell to ensure that the voltages are all the same.