Voltage Drop (no light flicker ever)

[UnderLoK]

I'm running dual 270 alts and see my back battery bank drop to mid 12 immediately and then it winds up in the high 11's low 12 with a quickness after that (see 1v drop from battery resting in maybe 30 seconds full tilt). Looking for opinions on potential problems. Below is my setup...

**All wire is OFC Kicker or KNU

**All copper is 1"x.5"

**I do not clip, I'm normally 3 ticks down on the deck from even distortion at 12.9 so plenty of head room

2 270a alts

5 front frame grounds to a copper bus (all less than 4' 2 of them are 2')

4 grounds, 2 from each alt to the same copper bus which are 1'-2'

1 power run per alt, they are only a foot long so drop for 220-270a should be next to nothing

4 rear frame grounds at around 5' max

48" copper bus in the rear

4 power runs front to back (more than enough for 2 270a alts IMO)

1 S3400 up front

5 D3400 in back - batts are always charged after heavy use and sit on trickle at least 3 times a week

Now I expect some drop with 2 SAZ4500s at .7 each or the one at .35 like it is now, but I would expect to stay above 12v (the 4500s seem to heat up way faster on anything below 12.2 so I'm trying to keep them up there)... I'm going to double check my volt meter isn't forked again today, but figured I would reach out for other ideas. Also note I just redid ALL of my grounds, by that I mean removed them, cleaned/sanded them all, remounted them, and repainted them.

While I think I could have a dead alt, even with a dead one I would expect better voltage out of 6 G34 batteries, but maybe I'm expecting too much. Prolly just need a couple 350 alts, but I'll opt to try all the free things first then think about dropping more $$$$ on some 350s... lol