Converter burning up batteries

[stowaways]

We arrived at the workshop to find another battery which appears to have "burned" up. Battery is only a yer at old (full of water)... And converter is only a year old. Is this reasonable amount of time to expect from converter? Airstream is '69...

Thanks in advance for any suggestions you might have. Previously we were plugged into 110v at campground. At workshop, power cord from trailer is plugged into adapter for 100. Pulling very little electricity besides a small fan and few lights. 12 volt only running few small
Overhead lights.

No tvs etc

[TG Twinkie]

What type of battery and what brand of converter? When you say the battery is burnt up. Does that mean there is no output voltage?
Depending on the type of inverter, you can power the trailers DC equipment with just the converter. As long as you are connected to shore power.
What are the symptoms?
Do you have DC power?
If the battery has an internal short, it may be causing the converter to "crowbar". Whereby the output will shut down.
Try disconnecting the negative lead on the battery, make sure it is not touching any part of the metal on the trailer.
Then check to see if you have DC power in the trailer.
Also check the large (30 or 50 amp fuses or DC circuit breakers.
Let us know what happens.

[stowaways]

The battery is a Interstate battery deep cycle. The converter is a Inteli Power 9100.