connecting batteries in parallel or series, myth and theory

snipped-for-privacy@ipal.net wrote:

Ever wonder why the cells in a car battery are separated? If it didn't matter, they wouldn't do it. The electrolyte is conductive, but it's rectification qualities are nil.

No. The protruding pieces of plate probably get eroded faster as the cell is used.

Don't confuse the plates, which are in series, to the current flow in the electrolyte, which may have millions or billions (biwwions, for you Carl Sagan fans) of parallel paths between the plates.
The electrolyte provides parallel paths. How the area of one plate is arranged is immaterial, outside of structural constraints.

I don't know if that is important or not. Off hand, I would think that there is very little difference between sandwiched plates and two large ones of the same total area. I can't say for sure. I don't know.

I think not. At that point it's a chemical state. I can't see that 'migrating' across the surface. The most chemically active portions would be the ones to see most of the current flow to the other plate, however, until physical erosion teaches them a lesson.

Sure. Electrolytes can get gassed off at different rates. The distance between the plates, surface condition of plates and the sediment at the bottom of each cell also count. Not all cells are created equal. The weak ones put more of a load on the good ones. The gassing rate changes because of unequal current flow in a parallel setup. The specific gravity varies with charge and how much water has been forced out or mutated into hydrogen. Unequal current flow is where all the problems start.
These guys can explain it in a better fashion than I've been able to do:
http://www.ece.osu.edu/~fasiha/thesis/Fasih_Modeling%20and%20Fault%20Diagnosis%20of%20Automotive%20Lead-Acid%20Batteries%20 (final).pdf
or: http://tinyurl.com/57pp26
mike
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m II wrote:

Here is another way to look at it. Series strings have enough problems of their own. No two series strings can be 100 percent identical. When we parallel two or more strings, the chance for problems is multiplied.
He's a bit repetitious, but it's readable.
http://www.battcon.com/PapersFinal2004/SymonsPaper2004.pdf
mike
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On 7 Aug 2008 18:43:07 GMT, snipped-for-privacy@ipal.net wrote:

ALL Batteriea are series connected cells. A "flashlight battery" is not a battery - it is a single cell. A 9 volt battery IS a battery, as is a 6 volt camera battery, or a lantern battery. Car batteries are too.

Definitely an advantage using one big cell over 2 smaller parallel connected cells. I'm no scientist so I cannot explain why - but they will last a LOT longer.
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