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Sandy,

I agree with Ed's comments.  If it happens that a battery is shorted and 
heats up it should be part of the learning process.  I remember the 
first (and last) time I put a 9 volt battery in my pocket with some 
coins.  Make a great hand warmer!

Take a look at this video, titled "5 dangerous things you should let 
your kids do".
http://www.ted.com/index.php/talks/view/id/202

He says he is writing a book with 100 dangerous things.  I think adding 
putting a 9 volt battery in your pocket with coins might be a good addition.

I taught a class on electrical circuits to some 5th graders.  One thing 
was lighting an LED.  LEDs require a resistor in series to limit the 
current in a simple circuit.  If they connect the power supply (battery 
or otherwise) directly to the LED it will burn it out almost instantly.  
I had explained this to them and it was bound to happen.  This too is 
part of curiosity and the learning process.  I wasn't worried because I 
had anticipated it and was prepared with some extras.  However, in one 
class a kid hooked it up directly and I heard a pop and then a small 
piece bounce off the wall.  That was the first and last time I have ever 
seen one sort of blow up!  Lesson learned; with kids anything can happen 
and probably will.  This should be explained to the parents beforehand 
and "reasonable" precautions should be taken.  Like wearing eye 
protectors even when messing around with LEDs.

 -Mark-

 * Mark Fowle, Partner
 * SIGNAL-INNOVA
 * 2841 East 19th Street
 * Signal Hill, CA 90755
 * Email: mailto:markfowle@signal-innova.com
 * http://www.SIGNAL-INNOVA.com/
 * Phone: (800) 417-9060
 * Fax: (800) 773-7694

Ed Sobey wrote:
> ISEN-ASTC-L is a service of the Association of Science-Technology Centers
> Incorporated, a worldwide network of science museums and related institutions.
> *****************************************************************************
>
> Sandy-
>
> All batteries will get hot when short circuited, not just re-chargable ones. You could find some power supplies that have circuit breakers or just live with the possibility of having kids ruin batteries from time to time. I doubt that the kids will hurt themselves - they feel the battery and drop it long before any injury occurs.
>
> Ed
>
>
>   
>> From: Sandy Eix <[log in to unmask]>
>> Date: 2008/03/06 Thu PM 07:31:52 CST
>> To: [log in to unmask]
>> Subject: rechargeable batteries
>>     
>
>   
>> ISEN-ASTC-L is a service of the Association of Science-Technology Centers
>> Incorporated, a worldwide network of science museums and related institutions.
>> *****************************************************************************
>>
>> Hello colleagues,
>>
>> I have been told that rechargeable batteries are not suitable for "build a circuit" activities with kids because they can  get hot when short circuited and/or dump their entire charge at once.
>>
>> But I'd love to get away from using disposable batteries in our school programming, where we have kids building "dexterity testers" (in the style of the game Operation).
>>
>> Any suggestions or experience with this?
>>
>> thanks
>>
>> sandy
>>
>> Sandra Eix, Ph.D.
>> Exhibit and Program Developer
>> Science World
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>
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