alternator or something else?

[cfan10]

Okay got a jump Tuesday because when I turned the key all I heard was click. Had my mom to go and start it Wednesday everything was OK. So, today I went over to take it out and no start didn't even give a click this time. It has two cheapo batteries connected now. I'm guessing because it has a cb radio installed/radar detector/too many speakers and those strip lights everywhere.
Had auto zone check the alternator when I bought it said it was OK, checked batteries too and the aux batt needed a charge, didn't do it. That was the beginning of last month.
Sometimes when I start it if the CD player or radar detector is on it will kill, turn it off and it starts right back up with no issues.
Does it sound like it needs an alternator? As always thanks in advance.

90 suburban 350tbi dual battery