I was in dire need for a Dewalt battery for powered drill, but my good one was at my local Makerspace and I could not be bothered to drive over there at 0100 in the morning.
I remembered that I had bought one some 15 years ago in a supermarket. After I dug up my basement looking for it, I found it in the store-room with a dead battery.
I will show now what I did to reanimate it, for fun and… fun.
Step 1: Take Apart the Battery
The battery pack was held together with 4 screws. After loosening them, it fell apart into three pieces:
Old batteries (dump)
Top cover with contacts (need new wires to go to the new battery)
Llower case (needs holes for battery wires to go through)
Step 2: New Energy
I decided to use a lipo battery pack as my new power source. My drill originally had a 12V power source, so I needed a 3 cell LiPo pack.
I had an old cordless drill battery for Panasonic with a broken cell sitting on my desk for ages, and took the occasion to finally rip it apart to build a new battery out of it.
This is quite easy, but I found no instructable detailing how its done.
Step 3: Build Top Case Connector
Easy step, find a matching battery cable, solder it to the contacts in the top case.
Maybe your drill is old enough that it doesn’t matter, but watch out for polarity anyways!
I want to have the battery connector outside of the plastic case, thats why I left the cables that long.
Step 4: Lower Case
Now I had a problem. I needed to drill holes to get a working battery for my drill. The Hitachi cordless drill battery was empty (after sitting on my desk for month).
Adjustable desk power supply to the rescue!
I put 2x two holes next to each other, broke out and filed of the middle to have two long holes.
Step 5: Assembly
The battery fits nicely. The reason why I wanted to put the wiring on the outside is:
I need a easy way to access the balancing port for charging and use of a lipo warner (recommended)
I want to be able to disconnect the lipo from the contacts