Automatic battery disconnect???

I did check in battery compartment when I got home and I don't see any loose connections or a battery disconnect. It has a 90W solar charger on it and it appears to be functional based on the led's. It has dual batteries that are less than 2 months old. The monitoring panel shows the batteries at 2/3 full when I looked at that after I got home. I can't believe after a 20 minute drive home, the truck could have charged the batteries to 2/3 full if they were completely dead. I deal with lots of batteries as my bass boat has 4, my golf cart has 6, my race car has a couple so I have lots of experience with them but this one has me stumped. Well I have them both on the charger tonight and I'll see what happens.

Sounds like adding a battery disconnect would be a good idea. Since the two 12v batteries are wired in parallel,where would be the best place to wire in the disconnect?