I was watching this video about potato batteries: http://www.youtube.com/watch?v=FITxr6bJmd8
He ends up connecting them in 3 pairs (parallel) of two (in series). This way, by connecting them in parallel, the voltage is not increased but the current is.
This confuses me. V=IR, so the resistance is what determines the current, given a constant voltage. So wouldn't it be more beneficial to connect them all in series, to get the voltage as high as possible?