Milwaukee M18 Battery Reverse Engineering

Summary

Coming soon... Milwaukee M18 Battery Dissection and Reverse Engineering... 2023-01-01: This project has been ongoing for a while... now its time to post some of this info and see what comes of it. I have access to several junk Milwaukee M18 batteries. Age varies a little. I thought it would be 'fun' to reverse engineer a battery just to see how it functions... That is until I actually opened the first one up and saw all the 0402 resistors and capacitors. Then it seemed like a 'fun-bad' idea. So here is the start of the first battery; Enjoy! (Reminder - Click on an image to get a larger version!) And here is our first candidate for reverse engineering: a Milwaukee M18 48-11-1828 18VDC 54Wh / 3 Ah Battery Pack. (Hey its the first one I picked up... I was aiming for a 5Ah and missed somehow... Didn't actually look very close at what I grabbed until the PCB was already removed.) Serial: B41MD 028567. This particular battery doesn't seem to hold its charge properly (indicator lights go up to full when charging, but put it on a drill and spin it for a second, and the indicator now reads two bars.) Battery voltages appear nominal though. Wasn't really interested in the cells themselves, so left this area of investigation go for the time being. After removing 4 tamper-proof torx screws and popping the top off the battery top casing off, we're left with a simple circuit board connected to 5 pins and 10 batteries (5 sets of 2 cells). Did I say simple? (I might regret that later...) I put this PCB under a decent camera (Sony A6300 with the FE 2.8/50 Macro lens) after removing the circuit board and de-soldering the connectors. And back side of the PCB... Sorry, I really shouldn't have used that 300W Weller soldering iron on these... I don't have the proper tip for the wide terminals on my Hakko... [Another reminder to get this at some point.] I really need to get the coating off these boards. After a soak in some solvents and a quick scrub with a brass bristled brush, we're lef...