Will a Dead Battery Kill an Alternator?

I believe that in general a battery does not necessarily kill an alternator. If a battery is low on charge, the higher voltage output (around 14v) will charge the 12.6 volts your battery is supposed to have. Therefore, an uncharged battery is nothing more than an additional load on the alternator when below 12.6 volts.

Can a dead battery damage an alternator?

Charging a dead battery with an alternator will result in premature alternator failure. When an alternator tries to charge a dead battery it must work at 100% capacity, but an alternator is designed to work at 100% for only short periods of time due to the heat it produces.

What will destroy an alternator?

Driving a vehicle through water that is deep enough to splash or flood the alternator can damage the alternator shaft bearings and possibly the brushes and electronics inside the unit as well. Water can also cause corrosion that over time will damage the wiring and bearings inside the alternator.