The Lime Battery

we wanted to see how a battery works. we put a zinc nail and a piece of copper into a lime and connected to a voltmeter.

one lime =0.95 volts two limes =1.96 volts three limes = 2.9 volt and lit up a l.e.d. 

Does it depend on the size of the lime? - No

What if I put in more nails and copper? yes, you can. 
https://www.youtube.com/watch?v=GhbuhT1GDpI

Can I use different metals - Yes

We (10A) also used a banana battery - it creates 1 volt more than the lime battery.