18V 10-Cell 21700 Battery Replacement Case for Milwaukee M18 48-11-1865 - DIY Repair Kit for 6.0Ah and 8.0Ah Batteries (Battery Not Included)

Fits perfect, functional as original. No problems.

We used this and some 21700 cells to craft a fully operational Milwaukee Tools 18V M8 battery. We tested it and it worked well and charged fine for routine work with a pole chainsaw and a leaf blower. The instructions were minimal, but if you are willing to do your own spot welds, the wiring diagram is probably enough for you. Some soldering is needed to attach the battery contacts to the BMS. The only challenge we had is that the terminal metal contacts were too thick to weld to one another with the small handheld portable spot welder we bought for purpose. The metal is pretty thick and Im not sure it is even nickel. We had to buy a more powerful spot welder to get that to work. At highest power, fully charged, it did the job. Spotwelding the batteries to the contacts was easier. We were new to this task. My son picked up the unit assembled with batteries but without the welds in place. One of the battery contacts shifted over and developed a short with the one next to it, quickly burning my son's hand. After a week he had recovered so we decided to spot weld the thing once piece at a time more methodically with some tape to hold lose bits in place and things went well. This was a fun and painful learning experience for my son. I'm sure he'd do it again. T'was but a flesh wound.

Works

I purchased two of these along with brand new 21700 batteries to build 8ah Milwaukee batteries. I did like the fit of the pieces and the build overall. I have not fully used these yet (future edit) but I do have a couple gripes. First off there are not enough screws to secure the backing to the red locking tabs. I only received three of the four. Secondly, while the fuel gauge pushbutton worked before final assembly, it didn't work after final assembly. Both exact issues happened to both items I purchased. Not good.

Was a perfect replacement for the 8ah battery. If there are no issues with the battery pack case itself, you can grind out the ribs in the bottom of the case and it will work perfectly.