You're mixing up two different types of caps and batteries. There are cap and batteries which use electrolyte fluids and ones that don't. Your amplifier internal caps contain fluid and can dry out, same with your conventional cheap batteries. Your big caps you use next to your amps do not contain electrolyte fluid, and nor does the deep cycle battery, hence the term "dry".

If your battery dies within 10 mins, cap has nothing to do with it. Your battery is damaged due to the abuse of leaving equipment running while the engine is off whether it is an accident, bad install, or intentional. By design non deep cycle batteries will slowly but surely become damaged everytime the capacity goes up and down and everytime the battery is near drain the quicker it will die as it won't be able to charge 100% ever again, and the percentage will keep going down, until the battery is only able to upcharge only enough to last you 10 mins like in your case. Your battery is damaged and may only be working at 10%, soon you will only have enough charge to turn over your engine even without using it with engine off on any equipment. You can either buy a new cheap battery and stop listening to your system with engine off entirely cause you will have the same outcome, or get a deep cycle dual purpose battery like a Yellow Top, and do what you want, cause by design it can take all the drains and chargings coastride. You can experiment if you want to satisfy yourself, so why not take the cap out and keep doing what you're doing with a new cheap battery and I guarantee you will have the same problem, so what are you going to blame next? Just save yourself some trouble and get yourself proper gear.

I am sure there are places that sell them. Other batteries can be used like Purple Haze deep cycle which sells at Canadian Tire.

 

I hardly ever have my system on when the vehicle is turned off and it just weird how i had the cap connected and the line was drawing 500mA but when i took out the cap it the line was drawing 450 micro amps

 

.5amp drain is pretty small.. thats smaller than one dome light working.. like even smaller.. your deck pulls around 1amp just to keep the time.. and your onboard computer drains maybe 1amp just to keep it alive.. i wouldnt worry about it and im sure thats not even what killed ur battery..

BTW when the car is on and system is bumping how much voltage drop to u have? cause if it drops low enough it will start to drain the battery and thats prob where it got damaged..

or even just the starting of the car drains the battery. sometimes when u have trouble starting the car and u lay on the key for 30sec it kills the battery too... everything will kill a battery. and system or not a battery dies man.. its just the nature of the battery.. we dont ask questions y the battery in the remote dies it just does cause we use it. same applys to the car....

get a new battery.. save up for a deep cycle since u have a system. u will thank urself one day.. lol sorry for the long post :P

 

when the car is running and pumping hard its around 13.2V and battery is fairly new got it April 2007 looking at a deep cycle but havnt been able to find a yellow top yet still looking

 

thats 500 milli amps (.5 amps) and 450 micro amps (.00045 amps) right?

First and foremost was that .5 amps with the stereo system off? If so that IS a lot with the engine off certainly enough to kill the battery if left on for a night or weekend.

Was that a cap with a digital display and if so was the display on? how much with the display off?

this almost makes me wonder if something isnt turning off

 

Yes the current readings are correct. Yes there is a digital meter on the cap and I believe it was turned off couldnt tell as i was under my hood with the meter and the cap is in my trunk. This was also with the car off and stereo off. From past experiances when i turned off my car the cap digital meter would shut off within 20 seconds. So when i take the cap out, i am reading .000450 Amps but with it in its .5A so i agree with you on something in the cap is not turning off and it may be the digital meter.