I have a faulty ni-cd power tool battery charger. Would it be ok to swap the circuit board out for a ni-mh one of the same output voltage and obviously swap the battery cells as well.

Many thanks for any advice

 

They each have different charge characteristics and should not usually be operated one for the other, when charging.

 

Replacing nicad cells AND THE NICAD CHARGER with Ni-mh cells AND Ni-mh CHARGER could work, but probably the form factors will be different. My impression is that battery powered tools are very intentionally made difficult to service or modify, and every possible effort is made to assure that no parts are interchangeable with other products.

 

What they are saying is that you should use a charger (or charger IC) designed for the type of cell that you are charging. The current limits should be constant with the size of the Cell.

 

Think of it this way, what are you preserving by starting with the broken NiCad charger? How is it different from starting from scratch.

Also, you cannot, in general, replace NiCad with NiMH of the same form factor. The NiCads have a significantly larger current capacity. I tried this with a drill / driver. Same voltage, same size, but it would not run on the NiMh batteries.

 

The TS DID state that the goal would INDEED be to REPLACE BOTH the Cells AND THE CHARGER. BOB mentions that the power density is quite different. THAT may be a serious problem.