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Battery Puzzled, Something is wrong here.

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Romodoc
#1
Aug21-13, 01:06 PM
P: 3
Ok, this may be a very stupid question but I just can't find a right explanation.

I was reading about how a battery works (i.e. car or AA battery etc) and I found several videos giving the following explanation. (e-) are concentrated on one pole and a positively charged material is in the other pole with an insulation in between. Plug a light bulb and (e-) will rush from one pole to the other passing trough the spring, heating it up, photos are released etc etc, you get light! perfect. The explanation works here.

However, most electronics connect this batteries in series, and in this case, the basic explanation above doesn't make sense. If I have 3 batteries in series (A, B and C) in a device someting like this:

device} [-/A/+] [-/B/+] [-/C/+] → {device

I can see how electrons go from C to A passing trough the device powering it. but how about electrons from A and B, how do they reach the device if there is an insulation.
Also according to this explanation, if put + of one battery next to - of another battery, it would drain one battery and leave the other with 2 negatively charged poles separated by the insulation in the middle. I know this is not the case, so I asume that explanation is a simplification of an obviously different process. Anyone could enlighten me?
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mfb
#2
Aug21-13, 05:19 PM
Mentor
P: 12,037
There is no insulation, the batteries are connected with wires (or by a direct contact). If more electrons flow into the positive side of C, more electrons can leave the negative side of C.
There are more than enough electrons in the battery material ;).
nsaspook
#3
Aug21-13, 09:32 PM
P: 663
There is a seperator (permeable membrane) in a some types of batteries to keep the plates from touching (shorting) and a electrolyte that conducts the ions that cross from one plate to the other and normally stop most electron flow. (that would cause self-discharge)

Lead Acid Battery: http://ecee.colorado.edu/~ecen4517/m...ls/Battery.pdf

meBigGuy
#4
Aug21-13, 10:58 PM
P: 1,084
Battery Puzzled, Something is wrong here.

If you think about it, there is no difference between a single battery powering a load (current out = current in) and the middle battery in the stack you drew (current out = current in). The same internal chemical processes are at work in the battery to keep a "constant" voltage across the battery terminals. The battery doesn't know the difference between electrons from a load and electrons from another battery. Either way it has to conduct I and maintain a constant voltage.

A perfect voltage source has 0 ohms resistance since it maintains the same voltage regardless of current.

As for the internal details, I really liked the lead acid battery link from nsaspook.


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