I had a phone conversation with a Forest River service manager this week about this issue pertaining to my Silverback 29RE. His comment was that the Cedar Creek units are designed for 4 six volt batteries in a series/parallel arrangement to provide 12 volts, and the battery compartment is sized accordingly.
The Silverback units are designed for 2 or 3 twelve volt batteries in parallel.
Remember that the inverters do not have a 12 volt charger built in. They are designed for pass through operation when shore power is connected, and to provide 120 vac when shore power is disconnected.
In both the CC units and the Silverback, all of the 12 volt DC systems are tied together at the batteries.
My dealer installed them incorrectly, and I could measure that the inverter battery was slowly discharging even with shorepower connected while the main battery was holding at 13.6 volts DC.
I went ahead and purchased another battery,....same brand...same size as the originals, and tied all three batteries in parallel. Everything in my coach is now working as it was designed and the batteries are holding at 13.6.
It took awhile for me to reach a good understanding of how it was designed, but once I understood and corrected the wiring, everything is good.
2016 Ford F-350 Lariat CC, 4x4 SRW. B&W turnover with extender. 2015 CC Silverback 29RE, fitted with Reese Goose Box. Amateur Extra Class K5TS, 2016 nights camped 16