Rechargable cells : What are Matched / Zapped cells.

[PoFF]

I've recently decided that I was tired of medium quality battery packs and I now aim to build one, ultimate pack.

My search for cells lead me to many RC car competition websites and altough I understand pretty much the concepts, those sites never quite defined what are Matched and Zapped cells.

I figure that matched cells must be cell with the exact same specifications (such as voltage, capacity and such), but how this is achieved and what big advantage does it gives to the user, since those cells are quite more expensive than the same unmatched ones.

As for Zapped cells, I've got no clue what it actually is, but my guess is that they send a high-current into those cells for short moment to do (no idea)?

Could anyone enlighten me?

Thanks in advance

[Blackthorne]

"NiCd batteries, when not used regularly, tend to develop dendrites (thin, conductive crystals), causing internal short circuits and premature battery failure, long before the 800-1000 charge/discharge cycles claimed by most vendors. Sometimes, these dendrites can be cleared by applying a brief, high-current charging pulse to individual cells, but once dendrites have begun to form, they will typically recur soon thereafter."

AND

"In the old days (ie. 80's, 90's) when NiCADs were more common, it wasn't uncommon for a cell to fail prematurely due to the electrolyte deforming enough to allow the anode and cathode to make direct contact. Especially common as the cell got older or if it was abused during charged / discharge. This would cause a dead short, the cell would go to 0V and never accept a charge. "Zapping" meant taking a higher-voltage source capable of a large amount of current like a car battery and for an instant placing that voltage across the terminals of the failed NiCAD. If you were lucky, the bridge between the anode and cathode would melt or vaporize and the cell could be charged and used again. If you were unlucky, the cell would become incredibly hot, vent, catch fire, something like that. I remember bringing back a 12V, 7000mAH NiCAD that had failed this way, by locating the failed cell and zapping it with 12V.

When people talk about zapping, they're talking about the same type of thing, only done to perfectly good batteries in an attempt to increase the actual voltage. Abusing the cells like that only shortens the life of the cells. Unless the cells are poorly manufactured to begin with and have bridges or near-bridges across the electrolyte, or some kind of impurities, it won't really help."

I'd have to agree with you on the "matched" . I would guess the battereis are tested and those detailed recorded, and then their characteristics are compared and matched for uniformity.

[thorvald]

Matched cells have been charged and discharged with their respective runtimes/capacity/internal resistance etc recorded. Then they are grouped together with other cells that have the exact same properties (or nearly exact...depends on how much you want to spend $$$$$).

This results in a pack that has a more consistant runtime and discharge rate. Was super important back in the day with RC racing when we had only 1200 mah packs (and smaller!) and 4-5 min races. You needed every ounce of current when running a hot motor/gearing and still make the full 4 mins.

For airsoft, don't even worry about it. Just buy the biggest mah pack you can afford and enjoy, discharge curves/run rates and internal resistance just isn't a big deal for the average AEG skirmish.

In other words, for the price of one matched pack, buy two large capacity packs :-)