Help me understand battery chargers.

[belomeclone]

So I had a Battery Charger a while ago, some kind of 15 minute Energizer battery. I did not like the batteries, so I switched to a Radio Shack brand, and I threw out the batteries and the charger.



I am going to switch to Eneloops soon. But I can get a charger that will charge both the Eneloops AND the Radio Shack batteries? How does this aspect of batteries work exactly?