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Old 02-22-2004, 02:32 PM   #16
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Originally posted by SS LS1
Post away! Love to hear the theory on the process of battery zapping (maintenance zapping not initial high current zapping the matchers use) for both Nicad and NiMih cells.

And of course since you let the cat out of the bag how about the custom engineered solution? Theory on that would be nice to hear. Will you be offering these to the public (assuming it is related to GP3300 maintenance)?
Most information about Ni-MH cells and battery zapping is common knowledge amongst people who design these cells. With that said, let me put forth some information that was created by others which may help you guys understand the theory behind zapping and Ni-MH cells. Please keep in mind that at this point no one is absolutely certain why zapping works. At this time the majority of theories are based upon a bunch of conjecture, which seems to make some sort of sense.

First lets have a lesson in Ni-MH battery chemistry - The Ni/H2 cell was an adaptation of the NiCd cell that used the NiOOH electrode coupled to a H2 fuel-cell electrode in a pressurized, sealed battery. In a NiMH cell, the anode is a metal hydride electrode that serves as a solid source of reduced hydrogen that can be oxidized to form protons. The anodic half-reaction is:

MH + OH- = M + H2O + e-

thus the overall cell reaction becomes:

NiOOH + MH = Ni(OH)2 + M

The anodes are comprised of hydrogen storage metals: classic examples of these include Pd and LaNi5, but these are not used in NiMH cells for a variety of reasons (for example the cost of Pd). The anodes used in these cells are complex alloys containing many metals, such as an alloy of V, Ti, Zr, Ni, Cr, Co, and (!) Fe. The underlying chemistry of these alloys and reasons for superior performance are not clearly understood, and the compositions are determined by empirical testing methods.

The NiMH batteries retain many of the advantages of NiCd, including long cycle life, and are signifcantly superior to NiCd's in energy and power density.

The exact mechanism by which zapping works is unknown. What is know, however, is that cells build up crystalline formations, as they are manufactured and later as they are cycled. These crystals cause tiny bridges to form between the plates inside the cell. The more crystal formations the harder it becomes for the cell to absorb and release energy effectively. This is refereed to as IR or Internal Resistance. A "Zapper" pretty much explains it's self. It's basically a transformer and huge capacitors that store up a very large charge and then releases it through the cell in a couple microseconds. This tends to shatter the crystals breaking down the IR in the cell and making it more efficient. Commercial zappers are very expensive and can pass as much as 30,000kva through a cell. There are less expensive "maintenance" zappers that put up to 90volts at up to 1kva through a cell to help keep crystals from building up.

What you need to remember is that zapping does not make a bad cell good. It makes a good cell better.

Oh and by the way.. Our zapper is for sale on ebay in case any of you want to buy it - http://cgi.ebay.com/ws/eBayISAPI.dll...tem=3177533194


Last edited by ghuber; 02-22-2004 at 03:04 PM.
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