[Hpsheff]

I recently installed a Rockford Fosgate Punch P300-10 powered subwoofer in my 2011 Ford Escape hybrid limited by tapping into the OEM sync head unit. The stereo works fine and the subwoofer sounds good for about 30 minutes of driving highway/city. After around 30 minutes the speakers volume is reduced and distorted along with much less if any at all bass from the sub. This continues until I park the vehicle for at least an hour. From the research I have done I’m thinking it may be a 12v power supply issue. The 12v battery is still under 3 years old and all vehicle electronics seem to work fine whenever I first turn on the vehicle. It is only after driving a bit where I notice any issues except for some glitching in the clock/stereo when the car has been sitting in cold weather over night. Any thoughts or suggestions would be greatly appreciated.

 

[zero_cool09]

This off the bat sounds like the amperage your demanding from the subwoofers amplifier is too great for the alternator to handle.
Of course I would suggest using a multimeter to check with the amplifier running, what type of current/amperage draw your making and then what level of current you have with the sub/amp off.
The reason for the delay in 30 minutes may be from the battery being able to supplement the demanded current, until it starts to run low itself.
Do your headlights flicker at all during usage of the sub?