Suzuki: Car A/c and battery problem, maruti zen, defective alternator

Question
I have a Maruti zen LX 2000 Model.My car's slows down and pick up dries up when I on A/C and the the battery discharges very fast.
Could you please tell me how A/C draws its electric power and is it works through battery and why pick up slowa down when I put on A/C.

Answer
Sorry, I have no idea what a Maruti is.  I live in the mountains of Colorado in the U.S., and am not at all familiar with any of the Suzuki vehicles past 1995 in the world market.  The only Suzukis I know well are the U.S. Samurai and the Sidekick, and the twin to it, the Geo Tracker.
Generally, on most cars, the alternator output goes to the fuse block, and then to the battery.  from your description, it sounds like either a loose alternator drive belt, or a defective alternator.  Don't forget to check the connections at the battery.  If they're fuzzy with white or bluish deposits, clean them with either a commercial battery cleaner, or baking soda in hot water.  I'm not at all certain what the a/c issue is.  Most smaller cars don't have much excess power, and sometimes when the a/c is on, it's necessary to shift to a lower gear or turn the a/c off to get significant acceleration.
scotty