Just purchased a Duracell 15 minute charger.
I have run it through several sets of cells (Duracell, Energizer and Digital??) and it works very well. The fan makes a little noise, but the airflow is pretty good. The fan runs for a while after the charge light goes out - it cools down the batteries very nicely. I can feel the airflow when I hold my hand over teh batteries.
The charger lists the current to be 8.3Amps for AA and 3.5A for AAA cells. The power supply lists the output to be 16V at 4A.
I took it apart to check inside because I am the curious type. On quick inspection, it has two PCBs, one for power filtering and one with the charging components. There is an insulating sheet over the charger PCB that I did not remove. The film has an opening over the MOSFETs, presumably to let them get some of the fan's cooling airflow.
Back cover. Note large holes for airflow. There is an nice arch in the back to allow for air to get under the charger.
Under the back cover.
PCB lifted a bit.
A view of the MOSFETs. Note hole in the insulating film.