My findings are different.
The 15 min. charger will charge a mix of AA and AAA. The channels and the associated sensors are completely separate.
The charger is very well done... the uP checks separately each battery for various dynamic parameters to decide if the battery is charged or not.
This methodology, I believe, has left -delta V in the dust.
One single LED for all batteries is a pity thing. Also, there are wrong information in the user manual, like the indication of removing the batteries at the end of the charge cycle without saying why, or turning off and back on the charger when putting in batteries.
I noted that putting NiMH cells at their end-of-life in the charger can cause erratic behavior.
Also, if you remove and reinsert a battery as the LED has turned green, the charger will not recognize it and will start charging again, with a risk of explosion of the battery. This doesn't happen if you allow the charged battery to cool down.
The most annoying aspect of the charger is the fact that it doesn't provide trickle charge. Leaving the battery in the charger, after a week, they read 1.3 Volts.
Anthony