Battery dies fast.

[diyanich]

Hi Guys,
My battery is dying once every 2 days or so,
I keep it charging every day,so I have a sure start at work,shopping mall parking etc.
FSR changed recently...battery is new form the dealer
if I get a weary crank,which happens often I just let the X idling for 5 min and it restarts like charm,so I assume the alternator is kind'a charging the battery.
I bought a battery/alternator tester that goes to the cig.lighter and it's showing no alternator LEDs when coming to stop or some equipment is turned on and they come on in about a second,so that shows that the voltage is dropping below 13.4 V or so.
So far I was lucky to start every time I had to go to work,but this problem is getting worse,so any advise is welcome.
Thankx.