Several years ago, I received a Craftsman 19.2v cordless drill set as a gift. It came with 2 batteries and, over the years, the drill and the batteries have served me quite well. About a year ago after a particularly harsh winter, I tried to charge the batteries but the charger showed them as defective. Turns out that if the battery goes completely dead, the charger believes that it is defective and will not charge them.
Thanks to the power of the Internet, I was able to "jump start" my dead batteries to where the charger would not see them as defective and charge them. I should note that the idea was not my own but came from the user FongBar via this post.
Since I believed that both of my batteries were beyond repair, I had already purchased a new battery that was fully functional. Having a fully functional and charged battery is important because this is how we will "jump start" the old battery.
To start, I went to Harbor Freight and bought these CEN-TECH 18" Low Voltage Multi-Colored Test Leads.These will be used to transfer the charge from one battery to the other.
Once you have the leads, the charged battery, and the defective battery, you are ready to hook up the two to start transferring the charge.
When you set both batteries down, you will see the terminals are setup in a cross shape. The two batteries will be connected in parallel, meaning that using the leads, you will connect the top terminal on the good battery to the top terminal on the bad battery. The same goes for the left, right and bottom terminals.
Once the batteries are hooked together, let them sit from 20 - 30 minutes. Once the time has passed, I put the old, defective battery on the charger and it started charging again. This procedure only has to be done once and your battery should charge normally from this point forward.
Disclaimer: This tutorial is without guarantee and all liability rest solely with the reader.