Originally Posted by btrayfors
6. In my personal experience and testing, flooded golf-cart batteries which are kept fully charged (14.8V absorption level) but not often deep-cycled will begin to show significant (more than 20%) reduction in storage
capacity after about five years. The deterioration in capacity begins much earlier. At six years you may have a battery
with about 70% capacity remaining. These are very rough ball-park figures. Note that for many sailors, a battery
with 70% remaining capacity is still "good". Therefore, I'd treat with extreme caution statements like, "my batteries lasted 8 years and are still good".
So, from this statement, if we have used our batteries constantly for 3 years, sometimes, but not every week, bringing them back up to 100% full charge, that's not too bad considering. I would say our batteries are on average about 75-80% full as a rough estimate. I would have liked to hope and get more like 5 years from a battery under heavy use, but I realize full time cruising is a heavy demand on batteries. We use a lot, but rarely bring them back up to full charge. Full time cruisers for the most part are not interested in running their engine
1-2 hours per day to do this, so we make do until we are at about 50% (maybe 4-5 days), and then run the engine
. During those 4-5 days, the voltage increases a bit, and decreases a bit based on load and alternative energy sources, but at not time is if ever back to 100%, no way.
Your test is at optimal performance, basically 0 discharge. Although, it would seem one would want to keep the batteries at a float level (13.3V or so), not 14.8 for extremely long periods of times. By doing this, did you actually harm the batteries, or just fill them with water
We charge our batteries up to about 14.7V when charging
by engine and solar
rarely gets up that high because of loads). I figured 14.7 (before temp compensation) is high enough, but is certainly from from the recommendation of the manufacturer. I hate it when the manufacturer tells you something that seems out of whack with the general consensus, and what seems like common sense.