Science Buddies: "Ask an Expert"

My potato battery is reading 1.5v-1.6v but I can't get an LED or 1.5v flashlight bulb to light up. I used 1/2 galv pipe and 1/2 copper pipe pieces stuck in two halves of a large potato. I figured they are hooked up correctly since my volt meter is ready 1.5-1.6v on the DC setting. I am guessing from what I have read the voltage is there but not enough amps to light the bulb? Is there another device I could use to show it works or am I missing something to get a light to light up? Thanks!

Ok, it works, just that the LED is VERY dim, we put a black box around it with a peep hole so you can see it lit. Guess there is not enough amps to light it brightly.

ccf955 - The veggie and fruit batteries provide for an interesting series of experiments, however, as you discovered the typical output is very low, on the order of 1 volt and a perhaps up to a few milliamps per cell, even given a reasonable surface area of the electrodes. You might find that you can improve the LED output by creating a two cell battery wired in series creating a doubled voltage. You might be operating near the forward conductance threshold of the LED and that might make a big difference. Red LED's have a lower threshold than other colors, so that might effect your choice as well. The flashlight bulb may require 10's or 100's of milliamps to produce an output, so is never a good option for veggie battery applications. Same goes for electromagnetic buzzers and motors.

Rick Marz