Muddydogs wrote:
Chuck_thehammer wrote:
Batteries by there nature "Self Discharge" even disconnected...
purchase a battery tender/ smart charger... or leave trailer powered up to 120 full time.
or remove battery and attach battery tender at your home.
Batteries do self discharge but not enough to worry about between trips or even for a few months as long as there is no draw on them.
Case in point. I have 2 group 27 deep cycle batteries that are at least 7 years old and one group 24 cranking battery about the same age that run my boats. I used the 2 deep cycle batteries last fall for extra AMP hours on my trailer while hunting for 2 weeks in cool weather. When done hunting I charged up all 3 batteries which then set until last week (8 months)not hooked up to anything. All 3 batteries had a voltage from 12.2 to 12.4 before being recharged and are now setting at 12.6ish after 3 days of setting idle.
Not sure why people feel the need to keep batteries hooked up and charging all the time but its not needed. A couple of my batteries have been left in the boat hooked up all winter long and have still showed 12.2 volts in the spring.
Muddy, I know your observations and measurements are spot on as I've seen similar results with different batteries left in storage. Most of mine recovered after a charge and seemed to operate correctly.
The truth is, though, that a battery left to discharge for a long time undergoes sulfation on the plates and loss of electrolyte density. Both of these reduce battery capacity. If a user wants to get the most longevity out of a battery, a float voltage charge should be applied and loads removed during storage. For most RV's that means disconnecting from the 12V distribution and using a battery tender while in storage.
