I took my packs apart today.
Is it me, or do the BMS's STINK? I mean SMELL, really, really bad? The 28s3p had a (2) BMS, one on each end (dated 2010), and all three 7s3p had a single BMS (dated 2009). All but one of the 2009 BMS looked thicker and lighter, tacky to the touch, and I had to take them outside because they were stinking up the garage. I wanted to disconnect them anyhow because I didn't know if they were draining current.
The good news is that all of the cells on my 19v pack are the same voltage - bad that they are all low, but good that none are dead. Every cell of every pack has every voltage!
All the the cells were in balance relative to their respective pack. Wonder if it helped that I was a good customer.
I like that the same screws are used to mount the covers and secure the BMS on both types of modules.
I believe that the painted metal seperators are a soft metal cooling fin, so having one side of each cell is enough. The endcaps have nice, big, metal-lined holes through them, providing an excellent mounting points. The 7s have horizontal holes, and the 28s has vertical holes, but I think you can remove the liner and use either set of holes.