Solar trickle charger for caravan battery?

That looks cheap to me - maybe you get what you pay for?

I’d suggest buying from a reputable solar specialist like Photonic Universe to get a quality, reliable product. If you want to trickle charge in storage, I guess you’re looking for something you can securely mount on the roof? You can choose between a rigid or flexible panel depending on the location for the panel. A 10W solar panel will output a little under 1A or 20W a little over 1A. I’d recommend the latter to keep a leisure battery charged which is subject to some battery drain e.g. alarm.

Mounting kits are available to screw or bond the panel to the roof. Cable can be directed through window gap or waterproof fittings are available for a small hole cut through roof or side panel. A 5A controller will be needed together with a 5A fuse fitted close to the battery terminal.

 If you can park the van facing south a good suitcase one in the front window should do the job. 

 Yes it would do the job, but you would be better putting the kit together yourself.

Panel is important and the best ones I have found are the flexible ones designed for boats, very robust. Something like https://www.ebay.co.uk/itm/High-Efficiency-30W-12V-Flexible-Solar-Panel-for-Camper-Caravan-RV-Boat-SALE/264438934983?hash=item3d91c9edc7:g:o~gAAOSwYSlXhn54

Monocrystalline cells are best balance for efficiency to price.

You need a decent charge regulator and some cable go for 2.00mm2 size to minimize volt drop.

Dont use croc clips onto the battery bolt it properly.

If you are not mounting to roof then get one an inch smaller than the window you are putting it in and just sit it on the sill inside the window catch handles. You need the whole panel to be in sunlight to get efficient output so it has to be smaller than the window.

Anything 30W or above will keep your battery topped up and healthy.

Not so sure about that, getting the right angle for the sun in winter and loss of solar efficiency through glass/perspex in low light conditions renders them fairly useless in my experience.

They seem to work in the front window for Dan ..... https://www.google.com/search?q=trudgians+solar+panels&oq=trdgians+solar&aqs=chrome.1.69i57j0.10523j0j7&client=tablet-android-samsung&sourceid=chrome-mobile&ie=UTF-8

I’m sure it does, but a 100w panel just to trickle charge a battery is a bit OTT. Two 50W panels = big, expensive and 50% of the output is used simply to offset the loss of efficiency due to location behind tinted, plastic window. Looks like Dan has a nice sunny location, not everyone is that fortunate. Buyers choice. 

Currently, I remove the battery at the storage site, and trickle charge it at home. Back issues, mean I now want to leave it in the caravan. Seeing the roofs of all the caravans become dirty very quickly I have discounted roof mounting. I bought an 18watt small panel and placed in the non tinted window facing south and it was useless. I am just at the point of buying a solar panel to charge my battery whilst in storage with the alarm on. 

So now I am considering a 100 watt foldable suitcase one, with a good 20 watt controller, just like Dan Trudgian has done. However, on Ebay there are a number for sale, but all sort of prices. How do you decide which price point to go for?

one of the storage pitch users near us in the compound (retired BT engineer and  and owner of one of Rosas dogie friends has a portable Aldi as we have been useing for our car solar panel that he just puts on the roof of his caravan connected to the batt and says he has never had a problem with it keeping batt alive for the alarm in the three years he has had it ,just have to remember to remove it before settiing off