That method is called the "nuclear charge" as I've seen it. Yeah, basically the wire is to provide some small amt of resistance so its not quite a dead short. Like a CV charge w/ barely limited current. I saw a wattmeter graph of it, and some of the initial charging was like 40-50A+
but obviously tapered off towards completetion. The idea is you try to match the # of cells to the lead batt, ie for 10S you would hook up to a 3S lead batt, then cutoff before it overvolts. Some people were charging M1s in like 5min depending on current limiting.