Jmai22

i need help fast. today when i went out to go to school my sound system didn't work. so first thing i thought was oh crap my shiet got stolen so i ran to the trunk and opened it up and everything was all there. whew. but for the first time it my life i saw my capacitor reading at 7.4v and slowly dropping .1v every 5-10sec. i thought this was really wierd to i got in the car and turned off the headunit so everything would shut off. after driving around for 5 min tried turning everything back on again and still no sound. why is my capacitor reading such low voltage. did my car battery just eat shiet. if it did how come my car is still starting up fine. i thought it took 9.6v to start a car when i only have around 7v. HELP ME FAST