The discharger is basically in parallel with the charger output wires going directly through the fuse to the pack.
The splice in this case was made inside the connector strain relief, which is tricky to do well.
The light aluminum enclosure got to a max of 170F, which could burn your skin, but because of the stand and rubber handle, it is safe to use as long as the ambient temperatures are not too high.
The pulser 50% dutycycle mode is for determining internal resistance.This measurement of the very low internal resistances of the subpacks needs to be made right on the battery terminals to eliminate any voltage drops through fuses or connectors.
This approach to the discharger is Rugged, can work with all batteries in the 100-220 V range, encloses the hot bulbs where they are safe from damage and has a case designed to dissipate the heat that is generated. The Power mosfet is also protected and in a cool place in the wiring box, and it has a nice output cable that can tie directly into the discharger adapter cable.