12V battery/batteries question

[cgtech]

Perhaps someone "restored" those batteries by pouring in some new acid. In theory (under perfect conditions) the battery should never lose any acid, nor ever need any acid added, only some distilled water. Its original "acid package" should be there for the life of the battery. A acid addition later in the batteries life would show some nice SG readings, but it's a fools errand. Higher than normal acid content will enhance (boost) battery performance, but with the trade-off of shortened lifespan. I believe you might have "rebuilt" batteries. That's only one of the reasons i don't love US batteries, they run higher acid content when new (higher charge voltage, higher SG readings).