Battery

Sound like its over charging, Can you check the voltage going into the Battery. 

When is the boiling happening? 

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Probably not actually boiling, as in emitting steam, but gassing due to overcharge.  Gases when mixed can be explosive so lots of ventilation and NO FLAMES or SPARKS.  

Thanks for all your help have disconnected it can't understand why it's over charged plugged into bollard on site

I guess the charger in the caravan is faulty or the battery is beyond usefull life and it will gas wherever you connect.  Try borrowing a battery from someone and you will see which it is.  

Sounds like the battery fluid is low and a new battery is required.

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The power supply feeding the van is club site bollard if it is this do I have a claim

See DD's post above.

The problem is with your battery and/or charger.

I trust you have disconnected the battery in the interests of safety.

With due respect free2419 your energy supply isn’t your issue, as has been mentioned it is your issue as the C/Van & Battery is your responsibility. Site power supplies have inbuilt systems for surges🤷🏻‍♂️