Like Chris stated..converter issue......loss of 12V DC power
Converter supplies DC when AC power is available and maintains battery.
If converter is NOT working then battery supplies all of the DC until battery goes dead.
Could be converter has failed.
Could be AC to converter has been tripped.....either a AC circuit breaker for converter has tripped OR if converter plugs into an outlet that outlet may be feed from a GFCI Outlet (Kitchen/bathroom) that has tripped
As suggested......get a battery charger and hook it up to your TT battery to recharge it
Converter DC output S/B 13.2V DC MINIMUM