Battery charger
 

What is your perfered battery charger?

battery charger
 

Get a 5 watt solar panel and leave it connected to the battery when not camping or disconnected from an AC source. Keep terminals clean at all times. Check the cables to ensure that they are tight connections.

I have a 33watt 2amp solar mounted on the roof but it doesn't work to well when I have the trailer covered. May need a aux panel (no budget for that right now) I use a 2amp charger for a couple of days before I head out to top off the batteries.

I use a trickle charger. I bought a handful of them at Harbor Freight for $4.99. You can keep it plugged in and not have to worry about overcharging your battery.

Take a look at Battery Tender, the Jr. model should be all you need to maintain your battery.
Battery Tender - Home of the Battery Tender Jr. - Batterytender.com

Solar panel
 

My 15 watt solar panel maintains the battery well! Usually abt 12.3 Volt.
My factory installed panel was originally wired incorrectly at the charge controller (my charge controller was accessable at the refrigerator panel cover outside). My original panel quit on me and I bought another, which went bad within the warranty period due to moisture problems. Before installing the replacement panel I sealed it with a high grade silicon at every possible visible entry place. I spliced the wire inside the flexible wire cable cover (in our bathroom) so there would not be any wire splices exposed on the roof area.
My motto is fix it if it is broke, so I worked on the original panel and found a simple solder job in the end of the panel restored it. I now carry the extra panel for boondocking and attach it, with a charge controller, direct to the battery. I also carry a spare charge controller (made in China), as a precaution.

2004 27T
2004 Expedition