Mechanical charging base modification.
Automatic chargers don't last forever. The internal circuitry eventually burns out. The Craftsman charger that I have was discontinued many years ago. Sometimes they appear on EBay, but you have to get lucky to find a good one. Two of them were defective, but are useful for spare parts. This thread shows a modification on how to convert an automatic charger into a mechanical charger. It has one advantage over the automatic charger. The automatic charger requires that the battery still has a partial charge in order to recharge it. There is nothing electronic in the mechanical charger, so it's capable of taking a battery in any condition.
Note: I don't take any responsibility for battery or property damage. Do this mod at your own risk, and never supply more current than the battery is capable of accepting.
Here is the original charger:
The charger will require a mechanical timer:
This timer has a maximum setting of 60 minutes which is similar to the original automatic charger. The two metal mounting tabs are easy to remove since they are connected with two screws. This is a bottom view of the modified circuit board:
This photo shows how the timer connects to the case:
The case is lower in the front which makes a perfect fit for the shape of the timer. The charger originally had three indicator LEDs in the front which were removed along with the other electronic components. The spacing on the case was the exact size for the spacing of the wires coming out of the timer. Here's a banana plug kit for the charger:
The banana plugs are unscrewed from the plastic insulator:
Here's a close up view of the banana plug:
The original plug was cut off, and the banana plugs were soldered on:
I have an old bench top power supply with banana jacks. A customer of mine had it sitting in his basement for many years, and thought that it was garbage. The switch was broken, but was easy to replace with a spare that I had on hand.
Here's the whole thing with a battery charging: