ok im running a kicker l7 15 and 6 speakers off of 3 amps. (L7),(front 4 speaker) and (back 2 speakers). i have extra batt in my trunk with a 1gage wire running to the front. ok heres the prob. when i turn it up and the 15 hits the low voltage light comes on on the amp running my front 4 speakers and they trun off till i turn it back down. how do i fix this? do i need a 3rd batt?