Here's a copy / paste of something I posted previously:
The old converter / chargers often have a steady 13.8v DC output. And, on the alternator side of things, there's often a voltage drop caused by the isolator and or the gauge of the wiring.
Typically, in a rig with an older converter / charger and an isolator and small-ish wiring, the battery never gets fully charged (14.4v dc). That chronic undercharging and partial state of charge cycling shortens the calendar life of the battery.
From the Centurion manuals I've seen, the max voltage output was limited to 13.5 to 13.6 volts.
It's not good enough to care for expensive batteries by itself. You'd need to supplement it at least occasionally with a charging source that will fully charge the batteries.
If you like the RV and don't mind spending a bit on some upgrades then replacing the Centurion is the way to go. Here's an option: Centurion CS 3000 Replacement
I think your Centurion was the power center for both the 120 volt AC and 12 volt DC loads in the RV. If so, it would be easiest to replace it with a similar sized all-in-one unit such as the one recommend by Best Converter.
This Centurion owner manual could be for newer units but the basic wiring layout might be similar.
CS OWNERS MANUAL .pdf