First, where is the Optima at?

Secondly, Did you meal #2/0 battery cable or #2 wire?

30 amps is not much because you're drawing something like 100 amps (2/3rds of 1500 amps @ 10-12 VDC).
I'd make sure your engine has 'excited' the alternator and has enough RPM's -- say about 1800.