Smart way to go about doing this is buy one battery at a time and see if you need more.

I have (4) D3100, (1) D3400, and (1) DC 320amp with (2) SAZ-3500s.

On full tilt i'm 13.5+

NIIIIICE!!! Thank you!

Smart way to go about doing this is buy one battery at a time and see if you need more.

I have (4) D3100, (1) D3400, and (1) DC 320amp with (2) SAZ-3500s.

On full tilt i'm 13.5+

NIIIIICE!!! Thank you!

You still getting a SMD?

I would try to simply replace your current yellow top, and see where your voltage sits. It would be the easiest and cheapest route. Also, how are you wiring your batteries? That also has a big impact.

yea that would be the most sensible thing to do. I have dual runs of 1/0 positive ran to the trunk. from there, i run both runs of positive to the 1st battery. Also have two runs of 1/0 negative ran to the 1st battery from the side wall in the trunk using (2) dual ground foots. from the first battery, parallel + and - to the second battery, and paralell + and - to the third battery. All battery wiring done with 1/0. Wiring in between batteries is less than a foot each.

Any scheimatics (pics)

I would try to simply replace your current yellow top, and see where your voltage sits. It would be the easiest and cheapest route. Also, how are you wiring your batteries? That also has a big impact.

yea that would be the most sensible thing to do. I have dual runs of 1/0 positive ran to the trunk. from there, i run both runs of positive to the 1st battery. Also have two runs of 1/0 negative ran to the 1st battery from the side wall in the trunk using (2) dual ground foots. from the first battery, parallel + and - to the second battery, and paralell + and - to the third battery. All battery wiring done with 1/0. Wiring in between batteries is less than a foot each.

Any scheimatics (pics)

I believe it would look something along the lines of this:

I forgot to draw in additional grounds to the batteries at the end. (never hurts to have too many grounds

Yes grounds grounds grounds. I actually have more grounds than batts (not that you have to have it that way) but again I like overkill. Grounding to the body is a no no though. Get your grounds to your frame. If you ground to the body then it can only transfer through the connecting points which is bolts and that only leaves the contact point in the threads which is not sufficient. Get the grounds on the frame and if you want to do it up then run a ground from the rear batt / batts to the block.