I recently joined a 9 volt cell and two 1.5 volt cells to get an output voltage of nearly 6 volt. For 15 minutes or so, the battery worked perfectly. It did not even show any sign of heating and in the next 2 minutes the 2 1.5 volt batteries hiss out and leave a lot of smoke. I am not even sure if its called an explosion. All the batteries were general purpose walmart batteries.
The batteries were connected in the following way:
My guess is that these particular cells were faulty/defective from the very beginning. Can there be any more possible and realistic reason for this kind of explosion?
PS: All the values in the circuit have been measured using a DMM and rounded of to nearest integer or 10th of an integer.