Dewalt tools are “guaranteed tough,” according to the Dewalt company motto. Nevertheless, the battery pack on any cordless tool is bound to eventually lose its ability to hold a charge. The only way to repair an old battery pack is to replace the old battery cells, which is less expensive than purchasing a new Dewalt DW9094 battery pack. Your Dewalt tool will be running strong again with not much time or expense invested, and you will have the added satisfaction of having fixed the battery pack yourself.
Remove the Dewalt DW9094 battery pack from your Dewalt tool. Unscrew the screws holding the battery pack together. Pry apart the two pieces that make up the battery pack, cutting any labels or stickers that hold it together with a razor blade.
Remove the battery cluster from the plastic pack and set it in front of you. Remove the wires or metal strips that are connected to the battery cell terminals by melting the solder with a soldering iron.
As each old cell is removed, solder on a new battery cell, taking care to orient the positive and negative terminals the same as the old terminals. Continue until all old cells are replaced with new ones.
Inspect all your solder joints visually, making sure that the wires cannot be wiggled loose with your fingers. Insert the cell cluster into the two halves of the battery pack. Replace the screws holding the pack together. Insert the battery pack into your Dewalt tool.
Give your Dewalt tool model number and DW9094 battery voltage to the supplier when you purchase new batteries, so that they can provide you with the correct replacement battery cells.
You can ruin a battery cell by heating it too much with a soldering gun. Only touch the iron to the Dewalt DW9094 drill battery long enough to melt the solder onto it.