Simple caravan charger question!

slightlymad

Ok then. I replaced my Ace Globetrotter's power supply around March with all being well. Off to Grin Low tomorrow so checked all Ok with the van. The leisure battery is dead, purchased same time (March). Simple question - should the charger output it's DC
supply at al times. I ask as it only does so when the caravan battery button is pressed, otherwise no output. The charger gets very hot and is buzzing so does not sound happy. Really, what I need to know is do you have to press the control panel to charge
the battery, or does it just trickle charge all of the time. 

Hope this makes sense.