Introduction: How to Fix a Broken Cordless Drill Charger

By ProjectJourneyman
About: I am a journeyman of projects - when I see something that I want to accomplish it, I do so with attention to detail and quality. I have a background in software and hardware, but also excel in DIY home improv…


Step 1: Verify What the Problem Is

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!

Step 2: Find a Donor Power Supply

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.

Step 3: Swap Power Supplies

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.

Step 4: Make the Wiring More Permanent

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.


Step 5: Reassemble

Simple, put the thing back together

Step 6: Results

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.

Step 7: Final Test

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.