Ok i have a 1 frag cap in my car and i had work done to the car the other day and not thinking about it they removed my batt and restored it without charging the cap back up...how can i tell if the cap is still good and i also heard that when you install a cap you should not share the ground for the cap and the amp...if i take the ground off do i have to charge the amp again.....and since they never charged my amp at the shop and just hooked it back to the batterey should i still try to charge it or did it already charge itself

 

It didn't hurt it. You only really have to charge it that way the first time it's installed IIRC. I've had my battery unhooked plenty of times and reconnected it without using the charge resistor the cap came with. I just charges really fast without the resistor and you get some pretty good sized sparks when you hook the battery back up.

Sharing gounds is fine. My cap and both amps are wired to a distibution block and all grounded together.