Ever since I installed my mini battery, my headunit hasn't been able to read SD cards, USB drives, or even CDs for that matter. I just use auxilary for now.

Any one else have that problem?

Or have any ideas on how to fix the problem?

 

Try putting the old battery back in and see if your head unit still acts up then take it from there. Whether it's a battery or a headunit related issue.

 

No headunit problems but at idle,cranking the stereo/sub will kill the car ! This is a PC680 battery,BTW.

 

Mini batteries and large stereos don't mix well. OP, try post #2, something doesn't add up here, that doesn't make any sense.

It doesn't work with the car running either?

 

First rule of troubleshooting, work your way backwards.lol If it still doesn't work, try just leaving the radio disconnected for a few minutes. That should reset it. (You can bypass this is the radio has a reset button on it. Usually behind the faceplate)

 

Try resetting the headunit, often times there will be a small reset hole behind the faceplate that you can stick a pin into.