Step 1 – Check the battery really is dead.
Before you rip you battery pack apart it’s a good idea to confirm that it really is the battery pack at fault. To do this remove the battery pack and measure the voltage across the + and - terminals with a voltmeter. As there are eight cells in the pack and the nominal voltage of a NiCad is 1.2V there should be 8 x 1.2V = 9.6V across the terminals. The minimum voltage a NiCad should go down to is 1V so the minimum voltage should be 8V. If its significantly lower than this you probably have a duff battery pack.
Step 2 – Assemble the bits and pieces you’ll need.
To perform this salvage you’re going to need to break open the battery pack , replace the NiCad cells and glue it back together again. For this you’ll need:A replacement set of 8 sub-C cells. Available from www.cpc.co.uk part no BT01300 (or click here for the whole page)·A craft knife (Stanley knife)·
Long-nosed pliers
A good soldering iron
Plastic glue
..And about 1-2 hours of your life.
Step 3 – Open the case.
Using the craft knife carefully cut open the plastic case as indicated.
Step 4 - Remove the battery pack.
Carefully withdraw the battery pack. Be careful not to damage the thermistor connected to the third terminal and taped against a cell. At this stage it’s a good idea to make a note of the battery polarities in the pack and their orientation.If your drill is not the same as this model you can establish the battery type by using the table below.
Step 5 - Confirm the failure mode
You might want to check the individual cell voltages since it may be that only one or two cells have failed, and so you only need to buy the cells you need.It may even be the case (as happened with my brother's drill) that the cells were OK and it was simply a broken connection.
Step 6 – Remove the cell interconnects.
The cell pack is interconnected with welded –on metal strips. By carefully removing this using long-nosed pliers they can be re-used.