Dewalt 18V NiCad to Lithium


I've rebuilt several of these batteries with NiCad cells and I'm not really happy with the time/cost of doing a rebuild. Add a broken solder from time to time etc… PITA.

My batteries tend to last about 2-3 years and I really dislike batteries that are near dead from sitting just when I need a tool to run. Drives me nuts to throw a pack on the charger so that an hour later the work can be done. NiCads are great if you keep them discharged and charge them only before use. 

New Dewalt's Lithium packs are over $100. Way more than I want to invest so I measured the inside of the case and found a pre made pack that had specs indicating it should fit. Ordered 3 packs and a charger for way under the price of a single Dewalt option.

Cut the protrusions from inside the battery case.

Then made sure the battery fit nicely

Pulled the power connector off a bad pack (wiggle it gently)

No need to pull it apart like the following picture … because nothing else is needed but the contact tip. The thermister is not needed so poping the solder off right there is much easier.

The new battery connectors should be pulled one at a time and soldered to the salvaged pack contacts.  

It fit snug in the top so a few dabs of glue should keep it in place.

What to do with the individual cell monitor/balance connector? Since I'm right handed I cut a hole on the right side of the pack for the cell level connector. It was a bit of a choice to wrap the wires and leave them loose or glue the connector to the side of the pack and where to put it. Changing the connector could provide better options for placement. 

Next was cutting parts from a charger to use… This will help ensure connections always right. 

The charge socket has stand-offs to position the contacts appropriately I guess. There was plenty of room to solder charge wires to the backside of the PCB cut-out. I used a piece of angled plastic I had sitting on my counter from a previous project to hold the PCB against the stand-off's via light pressure and a couple screws. 


I should note that the contact board is not screwed down and it is sort of floating but held snug by the plastic cover. It can't move much but does have enough play to keep it from binding when connecting to a pack.


OK… not real pretty but it is functional and should help prevent a LiPo mistake … :)

Now to test it!