I did destroy a battery by overcharging

my problem is overcharging, which can also irreversibly damage a battery. I learned this the hard way because initially I did not think the overcharging was a big deal. I found out my overcharging caused the voltage to drop to 8V, making the battery in fact even harder to save. Compare this to the sulfation which only caused the voltage to drop to 11V. Even bad sulfation can be partially reversed. Although the battery may still be too weak to start the engine, nonetheless it can still make a cranking sound.