Noob Battery Question
 

I know this is a very n00b battery question. But why do most airsoft packs use the 2/3 or sub C type battery? Why cant i just use AA batteries or other type of batteries in a custom pack instead?

i think its because those kinds of batteries are designed for one time use, or their not designed for long sustained uses

What if i get rechargable ones?

Packs made of sub-C cells actually make up a very small percentage of the airsoft pack market.

They're popular due to their performance benefit ratio. The smaller and thinner a cell gets, the higher the internal resistance.

By all means, go ahead and use AA, but there are better solutions available. There are a lot of packs made from full size "A" cells. AA is smaller. 2/3A (mini) is even smaller and has the highest internal resistance for any cell used for airsoft, but because the diameter is thicker than AA, it has less internal resistance.

The effect of internal resistance has been explained and described many times here over the years. But to put it in a nutshell, you want as little internal resistance as possible. The lower the resistance, the higher the current output capability, faster response times and higher ROF... without any voltage adjustment required.

If we could run car batteries, we'd all do it due to the huge performance benefits provided by it. But of course, the size is unwieldy and you'd sure as hell wouldn't strap it to your gun. We do our best to work within our limitations.

Kinda repeating most of what Illusion said but....

If your thinking of using those miracle energizer/duracell AA's that hold something like 2250mah, believe me most of them don't hold more than 1600mah in most applications.
The reason most airsoft batteries are bigger than AA's is simply because you want the biggest possible battery you can to fill up your battery compartment.
The physically larger cells are better to use because they are able to supply more amperage.
LiPo batteries are popular because they offer a significantly higher energy density than NiMH or NiCd, meaning more amperage and more voltage in the same size of battery.

blah blah blah

there's a few threads of batteries if you want to look them up, and if your thinking about looking at LiPo batteries, check out the newbie tank sticky thread that "m102404" posted :)