I would test the converter out put first to see if it is working or you just have a bad battery. What is the voltage reading across the pos and neg terminals of the battery when it is plugged in? What is the reading when the TT is unplugged taken the next day? In your photo take a reading from the large red wire to ground to ground while TT is plugged in. If you report back with these voltage readings you can help you determine if there is something wrong with your converter or your battery. The old Magnatec converters are very simple constant chargers and last a long time.