The following comes from Warren:

To check condition of any moderate-to-high current leads/connections, I like the measure-voltage-drop method. Eg: at battery terminal[s], put one vm lead on battery terminal itself & other lead on wire or connecting [crimped?] lug; do this while heavy charge/current is flowing.  Any more than maybe 0.1 volt = time to fix/clean/tighten.

Can do same type of test over entire cable as long as you can rig a long [thin ok] voltmeter lead to charger, but you’d need to check allowable drop [maybe 3%?] to know what is acceptable.