cap draining battery?

Hey guys/girls.. I have been having a ton of stereo problems as of late and just got A system (emphasis on A..not that system as its messed up) working.. Well before on my old system i had a cap, monoblock amp and my sub (as well as another amp running my 6.5s in the front).. so i was an electronics engineering student and know quite a bit about caps.. well heres my question.. is there any way to stop the cap from draining a battery without breaking the cicuit.. my guess is no.. heres what happend.. i didn't drive my car for about 3 of 4 days.. i go out to start and nothing.. test battery.. nothing.. try to charge.. nothing.. so i buy a new battery (canadian tire motormaster battery).. now the way caps work is they charge up to peak and slowly discharge (the whole point).. but seems my 2farad (or is it 4) cap must have a lot of leakage because after 4 days it had complety drained a fully charged battery.. Any ideas besides a different type of battery?

The battery went dead again? Well first thing I would do is do a current test at the battery to see how many milli amps are being drawn with and without the cap. If you see no change then it's not your cap, it will be something else causing the drain.2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

it is the cap.. I remember checking when i had my trunk open one day.. and i could see the voltage dropping across it and stuff.. im thinking about possibly doing this tho.. someone let me know if this would work.. Somehow running a switch to select wether the cap is engauged or to send the power directly to the amp.. i believe i would just need to put some kind of big switch in there and then put it in with the power cable and on the other side of the switch run another power wire to the amp.. but then i would still need to have the cap always hooked up to the amp.. Is there any way i can get something like this? or have the amp shutoff until it charges to 12.5-13 volts (after the car is running)??

Additionally, EVERY time you disconnect that power lead, if the cap is actually defective, then you will have a instantanous inrush of (potentially) thousands of amps, every time you reconnect the cap, by turning the switch on. I really have a hard time believing that your cap is actually bad. HOW, exactly, did you check its function to determine that it is bad? EXACTLY. And I am not asking about the "fluctuating voltage", that's perfectly NORMAL.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."