Don't forget! Even "float" charging Standard Lead-Acid batteries should be 13.8 volts. SO, your 150 watts divided by 13.8 volts is only 10.87 watts. Also, direct 90 degrees facing the sun on a good clear day is the only time you may see close to that. 150/12=12.5 amps, so there's a little question on your math there. Unless your batteries are already at 12v, there in need of charging anyway, and should draw the higher amp figure.
But, like the others have said, if it's easily done, check each panel by itself first
!