Originally Posted by bobw100ton
in spite of the claims, it stands to reason that since these are valve regulated batteries in a marine environment
and that Hydrogen gas rises....Something else is going on internally than the passive movement of all gasses to the "top" of the battery to reach the valve catalyst. It may last the warranty period but it's certainly counter intuitive that they are performing in the same fashion on their side. We get a lot of AGM batteries in that have failed for a variety of reasons but I have seen some 8D recently that failed that were on their side with case swelling evident on the upside of the battery.
Of course one anecdote does not a trend make, but here's our experience:
We have three AGM "banks" in our boat: 4 6V-200Ah AGM batteries for the 800Ah house bank - L16-types laying on their sides
, main engine
starter battery - single
4D 12V-200Ah, and another 4D 12V-200Ah battery for the windlass
. Both 12V AGM batteries are mounted normally - tops up
After 7 years (5 years full-time cruising, almost 4 years on the hook), the house bank and the engine
start battery are still working great. The windlass
battery failed (probably an internal short which overwhelmed the valve and breached the case).
So, in our case, it was one of the two normally-mounted batteries which failed. The house bank is still running great, but I wonder if re-installing with each battery flipped
would help redistribute any settled electrolyte and extend the useful life? I'll have to check and see where the valve ports
are (it would be funny
if they're currently near the bottom rather than the top).
│ + │ -------> │ - │
│ │ │ │
│ - │ │ + │
Granted, the main engine start battery gets very little use - our Westerbeke
T120-4A Century series engine starts up extremely quickly...