Converter starts/runs for a few seconds then stops

So I put my smart charger on them to bring them back up.
Plus thetrailer has been plugged for a couple weeks.

Thanks for the reply Roger.
I checked for voltage at the batteries and they tested 11.5. So it would seem it’s not charging.

Is it the converter that starts and stops or the cooling fan in the converter? The cooling fan is supposed to start and stop as needed to cool the converter. On cold days it will run very little as compared to when it is really working to keep the converter cool.