The following links provide a basic understanding a battery systems.
ASC Presentations on Battery Packs:
Battery Basics: http://americansolarchallenge.org/ASC/wp-content/uploads/2015/04/2015-Solar-Car-Conference-Battery-Electrical.pdf
How to Build a Pack: http://americansolarchallenge.org/ASC/wp-content/uploads/2019/02/190202_How-to-Build-a-Pack.pdf
Building Batteries with Li-ion Cells: http://americansolarchallenge.org/ASC/wp-content/uploads/2013/01/high_cell_count.pdf
Other Pages:
Lots of info here: http://liionbms.com/php/white_papers.php
Tons of detail can be found on this page and the links therein: https://www.mpoweruk.com/testing.htm#impedance
Dissipative vs Non-Dissipative Balancing (Active vs Passive): http://liionbms.com/php/wp_passive_active_balancing.php
NASA Battery Design Presentations:
https://www.nasa.gov/sites/default/files/atoms/files/darcy_-_nasa_batt_workshop_2015.pdf
http://cii-resource.com/cet/FBC-05-04/Presentations/BMGT/Darcy_Eric.pdf
Cell Balance: https://www.nasa.gov/sites/default/files/atoms/files/cap_bal_dur_li-ion_cell_life_testing_sklaus.pdf
Contains cell screening report: https://www.energytech.org/wp-content/uploads/ET2016Presentations/ET16-4G2DevelopmentofDistributedLithiumIonBatteryforSpaceSuitMiller.pdf
Masters Thesis on Battery Internal Resistance: https://dc.uwm.edu/cgi/viewcontent.cgi?article=1246&context=etd