Originally Posted by
Inor
Absolutely, it is worth a try!
On the Milwaukee tools, specifically, I would bet the tools are just fine. Most of the time, even when the tool quits working, the motor is fine; it is the battery that goes bad. The batteries can be expensive to replace so it is often as cheap to just buy a whole new tool than replace the battery.
If you can find a box of battery packs for them (even if the battery packs do not hold a charge)...
Cordless tool batteries are usually pretty easy to revive. Getting the plastic case open is the hardest part. Some of the newer ones just snap together, but older ones cannot be opened without damaging the plastic. - No worries. Use a cutting wheel on a Dremel to cut it open along the seams in the plastic. Try to keep the cut as narrow as possible so you can glue it back together again with SuperGlue when you get it fixed.
Once you get inside the battery pack, almost all of the manufacturers use exactly the same battery calls. The cells are called 18650's and they are an industry standard for everything rechargeable. Even Tesla car batteries are just several thousand 18650s wired together with a bunch of other crap for cooling, etc. They look like an oversized AA battery, but they are 3.6 volts. (Some of the newer ones may be marked 3.7 volts, but they are the same). If a battery pack cannot be charged or does not hold a charge, most of the time it is due to one cell being bad. Just use a VOM to measure each cell; the one that has significantly lower voltage than the rest is the bad one. Replace it and you are good to go!
I was buying 1-2 battery packs per year for my cordless shop tools. Since I figured out how to repair them, I have not bought a single new battery pack! That was over 5 years ago. I even watch yard sales and buy old battery packs and laptop batteries that do not work usually for pennies. I take them apart and the good cells become the replacements for my cordless tools when they need it.