Clicking battery

warrant1145

I have just had my van out for the first time this year. I have noticed that when connected to my car, there is a clicking noise coming from my battery box. When I first connected it, I couldn't get my fridge to work from the 12V system. On arrival at the
site, everything was working fine (12V and 240V). On returning from site, I connected up to my 12V system and found out that my fridge was now working but there is still a clicking coming from the battery box. The clicking carries on for up to 30secs after
I turn the car of. The battery is relatively new and was fully charged before my outing and I have checked to ensure that the battery connectors are in good order. Any help on this matter would be much appreciated.

Regards

Bill Turk