pdgage
Posts: 1
Joined: Sun Jan 17, 2016 10:29 am

### Battery that makes sense/cents

Can you help me alter the project using a flashlight light bulb? I know that a meter allows quantification, but for a child new to science projects, intensity of the light bulb will provide a feedback that is 'fun'... Thank you!

HowardE
Posts: 496
Joined: Thu Nov 20, 2014 1:35 pm
Occupation: Science Buddies content developer

### Re: Battery that makes sense/cents

It would probably help to know how much power it takes to light a flashlight bulb. The standard low intensity bulb in a 2-cell flashlight wants about 2.38V at between 0.25A and 0.6A. When you make one of these voltaic stack batteries out of pennies and nickels, what kind of voltage do you get and what did you measure as a maximum current output? If you look on the web you'll see that an LED (red, yellow or orange) needs a stack of 5 pairs of coins to light. An LED uses a lot less power than a flashlight bulb. Rather than spoil the fun of letting you do the research, I'll ask you a couple of questions that may give you the answer.

1) If 5 pairs of coins can put out enough voltage to light an LED that needs 1.7V, how many does it take to light a flashlight bulb that needs 2.38V?

2) If one stack has enough current to light an LED at about 5mA, how many stacks will it take to provide the minimum 250mA current to light a small flashlight bulb?

Fortunuately it's not expensive to experiment with pennies and nickels. Would it suit your purposes to light an LED instead?

Howard

LTN
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Joined: Mon Feb 15, 2016 1:38 am
Occupation: Parent

### Re: Battery that makes sense/cents

We did the "Battery that makes sense/cents" project and found that voltage was increasing when adding more coins, which seemed normal. However, current (in Ampere) decreased when we added more coins. We also found that the measurements of cureent were not stable (numbers decreasing quickly during the measurement). Is there anything wrong in the principle or measurement ? Thank you for your help.

Sci3nc3Stuff
Posts: 2
Joined: Sat Mar 26, 2016 1:56 pm
Occupation: Student

### Re: Battery that makes sense/cents

I don't think so because I also got the same thing three times. At first, I thought i did it wrong but after I did three trials of it and got the same results, I think it was part of the experiment which was the trend that was supposed to been seen after you performed the experiment. I hope this helped.