Quote:
Originally Posted by CT Jack
Joe K, you seem to be very knowledgeable about electrolytic activity, corrosion, conductivity & resistivity and I was wondering wouldn't filling the battery cells too high also add to the post corrosion problem?
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Anything above the plates is electrolytic inert. No purpose to battery charging, capacity or discharge.
That said, batteries (particularly in the Model A regulated or unregulated) can "hydrolyze" the water in them (over charging causes the water to disassociate and create hydrogen and oxygen which is why battery caps have "breather holes" - to let the pressure out) with a consequent lowering of electrolyte level.
So you either want to carry your level low and check level frequently lest it go below the plates (this is not fatal to a battery but it does cut into its capacity) or keep a modest surplus and check less frequently.
How much surplus is a good question. How often do you check?
As to level being high causing corrosion - corrosion is caused by the electrolyte being "thrown" as a mist by those hydrogen/oxygen bubbles on overcharging. Don't overcharge - no bubbles - or very few anyway.
A greater space above the water line gives the mist some "residence time" to drift back down and recombine with the water level - a "liberation zone" certainly. So to answer the question - keeping the level down SHOULD reduce the mist which escapes from those vent holes. And yes, a high level will tend to move mist outside the battery case causing corrosion.
Many battery vendors now include "recombining" caps with some sort of chemical to grab and re-associate the hydrogen and oxygen and limit discharge to outside. This is a spin-off of the AGM/Gel technology which attempts to limit how much gas/mist a battery creates. These technically should help with corrosion. I think these caps can be bought separately - although I have never used them.
I hope this helps. I'm not a fan of AGM/Gel batteries. Its nice to actually see and appreciate and be able to test with a hydrometer what exactly is going on in your battery - which "Maintenance Free" batteries true to their name are designed to prevent.
Joe K