How to Fix a Broken Cordless Drill Charger

This Instructable assumes that you identify that the problem is the charger itself.  In my case, a 15v power supply to charge 12v batteries was pumping out 3v.  Get a simple multimeter and measure the voltage at the terminals of the charger.   If the voltage is less than the rated voltage, then this Instructable might be for you!

Since my 15v power supply is pumping out 3v, I need something else that has similar power ratings.

The original:
15v, 200mA

The new supply
15v, 800mA

Well, the replacement is a bit overpowered, so there is a little danger here.  If possible, find one that is a closer match than this one.

I cut the wires to the original power supply, and tested the performance of using the new power supply before making it more permanent.

It worked as it should - actually, much faster than it should.   I need to be careful not to overcharge.

I soldered the wires to the original connection points and even made a pull-stop so pulling the cord wouldn't yank the wires out of the circuit board.

Simple, put the thing back together

Oops, it looks like I need to test my batteries with the multimeter every time I charge for more than 5 minutes now, because the new charger is a bit overpowered...  Once again finding a more closely matched power supply would have helped.

There you go, the light comes on and charging commences.  It looks like this project is complete.

Again, I put more details on my blog post , but the steps are the same.