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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?

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    \$\begingroup\$ Simply put, connecting three resistances in parallel reduces the resistance; increasing the available current. Connecting potatoes in parallel is probably safe, but connecting batteries in parallel is not usually recommended, and with some batteries, can result in destructive currents flowing from one battery to another. \$\endgroup\$ – Brian Drummond May 5 '13 at 20:09
  • \$\begingroup\$ The load determines what the solution is. If the load needs voltage of a certain value and hardly any current go with the these weak batteries in series. However if the load needs a certain minimum current you have to parallel them up. As all have mentioned using normal batteries this is not a good idea. The internal resistance of these batteries prevents large currents... and if the current needs to be larger and the voltage higher you have the parallel and series them.. This is a get you out of trouble, last ditched attempt to save your life solution... your in trouble then... \$\endgroup\$ – Spoon May 5 '13 at 23:14
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"Real" batteries are capable of maintaining their voltage while delivering significant current.

However, the potato batteries are not capable of delivering much current - they have a relatively high internal resistance, so the voltage will drop significantly when they are delivering current. Putting the potatoes in parallel doubles the available current.

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