batteries with different potential in parallel

n9352527

Joined Oct 14, 2005
1,198
The outputs are most probably heat, smoke and electrolyte, in that order :D

Seriously, it depends on the internal resistances of both of them (or the current capabilities). The one that has the largest current capability will win. And please don't verify this with an experiment :p
 

beenthere

Joined Apr 20, 2004
15,819
Hi,

The only application is to make an IR source for a reference to aid in night firing of mortars. They use two 9 volt batteries snapped together for the heat source.
 

Thread Starter

sinlikenkuri

Joined Jul 31, 2006
7
The outputs are most probably heat, smoke and electrolyte, in that order :D

Seriously, it depends on the internal resistances of both of them (or the current capabilities). The one that has the largest current capability will win. And please don't verify this with an experiment :p
i asked this question because i'm stucked in circuit analysis during an interview. although i know a very large current will flow and may cause heat, the interviewer want to see any computations using every circuit analysis i learned from college. so what i did was to assume internal resistance values but there i am stucked again with the two diff potentials in parallel. anyways, thanks for all the inputs ;-)
 

thingmaker3

Joined May 16, 2005
5,084
Its not so much that doing so isn't allowed - its just that no good comes from doing so when the potentials don't match.

For equations:
1) try picking a wire size and length, or a trace size and length - calculate resistance therefrom
2) Using internal battery resitances and the conductor resistance, calculate current flow and the temperature rise per unit time - compare to heat dissapation rate
3) impress the interviewer with your ability to gage not only the time required for the copper to melt, but the ammount of light (if any) produced
4) further impress the interviewer by calculating battery temperatures after the wire pops - also calculate amp-hours remaining in each battery

I would have failed this interview. My people skills end when questions like this begin. :rolleyes:
 
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