Car Stereos: 2 seperate batterys, heavy gauge, ford expedition

Question
I have 2 monster 18s in the back of my ford expedition and a monster Persision Power mono block amp to power them. I have 2 brand new optima blue tops in the back with everything hooked up together. And an 8g wire going from my front battery to the back. But the two batterys in the back are dying, idk what it is but i can fix it if someone could tell me what the problem is. Please and thank you.

Answer
Hi Dillon,

The first thing I'd do is upgrade the power wire going two the batteries.  8g isn't nearly enough to be connecting optima blue tops to the car's system.

Then, make sure you have a good heavy gauge ground for these batteries and it's a short, clean ground point, with a clean connection to the chassis, and a secondary connection to the ground on the battery.

Justin