Mounting AGM batteries on their side

[sully75]

Just wanted to triple check, I have two west marine 79ah AGM batteries. I'm looking to relocate them. It would be easiest if I mounted them on their side, vertically. It appears there's no problem doing this? It does say not upside down.

Since I'll be glueing my battery box in I wanted to double check. No hits in performance or safety if I do this?


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[Sandero]

any position works.. secure batteries for a roll(over)!

[sailinglegend]

You don't need battery boxes!

My RedFlash starter AGM has been on its side in the bilges for 11 years.

[smac999]

I've only put AGM batteries on their side twice. both times the batteries failed within 6 months. (with the boat at sea, lost house power) I'll never do it again.

[HopCar]

My AGM batteries have been on their sides for many years without problem. Putting them on their side allowed me to move them to a space that wasn't otherwise usable.

[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.

[Beausoleil]

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...