I'd have to agree with connections. I did, however hear of an internally corroded battery cable. I once had a corroded bulkhead connector do it.

In one case the paint shop didn;t tighten the battery cable. Could I prove it? NO!

Between the bulkhead connector and the alternator where the rotot solder joint just broke, I don't know what was more difficult. The corrosion was harder to find. The broken rotor connection gave no indication, whatsoever. The car just stopped.