140 amp alt , 2 air zenith comp , 1 battery

[unclewatts]

As has been mentioned before on this board, the battery does not run the accessories when you are driving, the alternator does. However, I would think that a 140 amp alternator would be plenty strong enough to run the stuff you mentioned. Remember that your stereo is not a constant load (Like your compressors are) but a dynamic load. Some car stereo guys put in 1 Farad capacitors in parallel with the 12 volt supply to their amps for just that reason. If you are still concerned, buy a real heavy duty Group 24F battery in the 700 to 1,000 CCA range but I really don't think IMHO that you need to go through all the hassle that installing a second battery entails. BTW, 1 wire alternators have the problem of not charging very well at low RPMs. I hope that doesn't cause you any problems down the road.