How many other items do you run off the house battery when you are sitting? I run 2000 watts on 2 27 batteries for hours with no problems. I then have 2 other 27's for start up or reserve power. If you have a high power deck and you are running speakers off of it, the factory powerquest wiring is not big enough. Make sure you have speakers wired correct and not too many ohms going to your system.

heres the perko diagram for 3 batteries

Speedreeder, Stereo Only , 2 - 4 channel amps 70 watts per, 6 -6 1/2" speakers and 1- 10" sub. I really think it's the way I am positioning the battery switches for starting and running, I'm hung up on trying to run each engine on it's own battery instead of the switches in the "All" position