Making batteries from fruits and vegetables

[gizzer]

We are doing a science project off of this webside called Making batteries from fruits and vegetables. We can come up with 5 volts using a 8 potatoes, but we can't make it power a 1.5 to 3 volt buzzer. Can you give us any idea what we are doing wrong?

[davidkallman]

Hi gizzer,

I assume you're doing the project at:
https://www.sciencebuddies.org/science- ... p029.shtml

Two thoughts:

The paragraph containing "If a battery or a voltaic cell doesn't provide enough current, you can connect a number of batteries or cells together in parallel (see Figure 2 below)" suggests constructing multiple batteries and connecting them in parallel.

The second thought is to change to a citrus fruit for the battery:
http://wiki.answers.com/Q/Which_fruits_ ... ty_and_why

[Craig_Bridge]

The amount of current each cell can produce is affected by surface area of the electrodes. The more surface each electrode has, the more current the cell can produce. You may want to try bigger electrodes before you try parallel cells.

A buzzer I looked up takes 35 mA and has a resistance of about 47 ohms which is quite a bit of current for these kinds of batteries unless you use large electrodes.