I found it educative. Also explains why multi 18650 "explodes" if you read the document properly. Simplified a 3x 18650 cell configuation and 1 of those bad can easily overcharge the bad one with 2 other pushing 8+V and overcharge the defective one. Kaboom guaranteed by defective cell venting and airtight flashlight.
Have a good time reading:
http://www.stensat.org/Docs/battery_test_results.pdf