Thanks for the help guys, fitting another battery seems to have worked, but need to give it a few days to make sure that it is being charged.

26 minutes ago, Kevin Taylor said:

Thanks for the help guys, fitting another battery seems to have worked, but need to give it a few days to make sure that it is being charged.

How will you be able to tell after a few days?

Presumably the battery voltage will start to drop.

Not after a few days it wont, you need to test it under load ideally with a load test meter, failing that you can current test the panel. The only way to test without a meter is to remove the mains for a few hours and see how long the panel stays live for, once the bell starts ringing put the mains back on for 24 hours, then remove it again. If the sounder sounds immediately the charging circuit is fooked.