if you don't leave the trailer plugged into shore power or have a battery disconnect switch, the parasitic power drains in the trailer, will drain a single battery down in just a few days.
you may have done permanent damage to the battery if it has been drained numerous times, below a certain amount of charge
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC