Hello Ann,
Most LCD screens are designed to work with thier own plug in power supply. These seem to be 12V dc, but because the power supplies are usually switch mode devices they produce a quite accurate 12V with a typical range of 11.5 to 12.5V or better.
In caravans, the battery charger will typically give out 13.8V dc, and when no mains is available most caravan applinces will operate down to 10.5Vdc. This is a much wider swing that the LCD panel would normally expect. In a car the situation can be worse, as the alternator in some models will give out up to 14.5V dc
As a consequence, and depending on the individual design of the LCD panel, some may work quite well in a caravan but others may not tollerate the wide swing in supply voltage.
My advice is to specifically ask (do it in in writing and get a written reply) if the panel will work in a caravan with a supply voltage swing of between 10.5 to 13.8V.
If you find your panel does not work, the you have written evidence that the product is not fit for purpose and you will be able to get your money back.