There are several low wattage SOLAR PANEL just designed for topping off the batteries when in storage. My JEEP had one laying inside the dash area and plugged into an active 12V socket. This did pretty good but was only a 10WATT model...
I would rather have a 20WATT or more small panel for that one battery... AMAZON has a several listed on their site...
If you expecting this to charge your battery in a three hour time frame this won't do that. This is just for leaving connected to you battery sitting in the high sun for longer storage time. It would be even better if you had a battery disconnect switch with only the small solar panel connected to the battery terminals.
I have multiple batteries in my battery bank and I switch them completely out while they are sitting on my trailer tongue. Then I will throw them on the trailer charger unit once a month for a few hours... When connected to shore power or a generator my trailer will re-charge these batteries to their 90% charge state in around three hours run time. Then I will totally disconnect them again...
The beauty of having your trailer parked at home...
Roy Ken
My Posts are IMHO based on my experiences - Words in CAPS does not mean I am shouting
Roy - Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
K9PHT (Since 1957) 146.52M
2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS