MartG
The current shows around 0.2 amps with just the radio going, and 3.5 when the fridge kicks in.From Andrew Bazeley -
The control panel takes 0.2A when on so your radio may not be registering - I think it uses about 1A.
... the other is 11 years old!
It's done well - I've found 'car' batteries usually decline after about 6 years.
On balance, I think I'll take it in and get the whole thing checked over.
Good idea, having two batteries in parallel, with one 11 years and one 3 is not good as the older one may pull the newer one down in use.
Finally, just use them, and keep them above 11V, give them a mains charge once a month for 24 hours...