Was in the battery compartment of an 05 yesterday and found yet another electrical drain issue due to physical config of batteries &/or cables. Since I see this a lot, thought it was worth a thread.
For those having 12V issues, check the overall layout of cables, & battery caps vs. the metal frame parts of the battery compartment, in addition to cleanliness & degree of corrosion present. It is not uncommon for a cable or cap to have been placed very close to frame metal or a metal holddown, and then some settling of contents occurs during travel. Once there is contact w/metal, any battery acid that is on the battery tops can migrate to the metal, cause corrosion thru the paint, and it is then an electrical leak from the positive post across the battery top in the acid to the source of ground.
We were at Jackson Rancheria w/NorCal and one of the Alpiner's had rapidly blinking lights on his inverter panel. He thought it was the inverter going bad, as another rig had just experienced the same symptom from a shot inverter. Instead his problem was a cable (still fully insulated so no direct short) touching frame metal at the rear of the battery box, wet from battery acid bubbling, rusted area on the frame. Took a volt meter reading between negative battery post & the bare frame at the rust spot: 4.5 volts!!!
Problem identified. Yesterday's experience: previous owner had placed some plywood under the batteries, elevating them and pressing a battery fill cap against the frame- same rusted spot & voltage leak. The wood raised the batteries about 1.5", so the owner is replacing wood w/a trimmed mudflap (about $10 at a local truck supply place, 24"x30" is the usual size and fits nicely as a pad under batteries).
There are various threads on adding mineral oil
to lead acid batteries to minimize boil-off of water & the concomitant acid splash. Its worth considering. But the direct contact issues will always be a potential still, and need a periodic check & adjustment when problems present.