Bailey Unicorn Vigo IV Charging Problems

[Mix1962]

Hi all, I have a 2018 Bailey Unicorn Vigo and have been having a couple of electrical problems - it has a solar panel. The 1st symptom was the motor moving not having enough uumph to move the caravan - I disengaged the motor mover and tried operating it without 'load' and the mover gear rotated freely. The battery voltage was only just 12V, although it didn't go over 12.4V during charge and dropped to below 12V after a few hours, so I replaced the battery - it was 7 years old, so not an unreasonable life - I have had the battery on an Optimate charger in the garage and it confirms the battery has met its maker.
A couple of weeks later I checked the caravan and noticed that the voltage dropped from 13.4V to 12.7V within about 20 seconds of switching the control on (the switch just inside the door). Nothing else was switched on at all. I've checked the voltage at the battery and it is definitely 12.7V, as per the display by the switch..
I think it's likely to be the battery charger (PS276-1), which is in the small locker under the fridge.
Does anyone have experience of anything that may lead to another diagnosis? Many thanks, Mick

 

[Mr Grumpy]

12.7 volts is the average floating charge for a fully charged lead acid battery.
13.4 volts would tend to indicate it's receiving a charge.