Burn your finger hot

This unit did not maintain my battery. Last year after many jump starts I elected to wire direct.

The bottom picture shows direct wire from house batteries. The red cover on top is a breaker. The yellow/silver component located on the battery box is a one way diode to prevent back feed from car to RV. It was working as intended until today. Upon arriving Hondo, Texas the car battery was dead. The battery was cool to touch. Not the breaker, not the battery case. They each were hot enough to burn. I will check this out while in Del Rio.