lime battery

https://www.youtube.com/watch?v=GhbuhT1GDpIwe wanted to see how a battery worked we put a zinc nail and a piece of copper into a lime and connected it to a volt meter.
1 lime=0.95v
2 limes=1.96v
3 limes=2.9v and lit up a LED

questions and wonderings
-does it depend on the size of the lime? (no)
-what if I put more nails and copper in? (it wont work)
-can I use different metals? (no)

the way that it works is the zinc and metal in the nail runs through the lemon. so, in conclusion, you can use anything that has enough fluid for the metals to flow through.

we also found out that a single banana holds(1v) which is .5 more volts than the lime