Hi fudgey,
"I wouldn't use more than 2*AA or 3.2 V without actually knowing the hardware well enough." Agree Guess no one has tried higher Volts.
Hi waterwingz,
"Depending on how your battery pack is constructed, you might be able to convert it so that it connects in parrallel two sets of batteries connected in series...." Thanks, have you ever done this?
Ken