Is our new caravan battery faulty?

We have just purchased a new Abbey Vogue 2 caravan and using it for the first time.Our new leisure battery shows it is ok (on the battery pack itself), however it seems to be charging up to about 10.5 volts but losing the charge almost instantly, even when nothing is being used. The caravan system stops charging the battery as soon as it drops below 10 volts, so we were wondering if it is more likely to be a faulty battery or a problem with the van electrics? Any help would be greatly appreciated. Thanks!