During an attempt at clearing the ruins within the first ten days I noticed that I couldn't overcharge myself as WX-78 by hammering the altar.
On the surface if an Ancient Altar is hit by a hammer it will function normally. Spawning random items/monsters and shooting lightning everywhere that said items/monsters are spawned.
However in the caves the the same behavior doesn't happen. The random items/monsters do spawn normally but the lightning doesn't come down like normal.
1. Go into the caves 2. Spawn in or visit an Ancient Altar 3. Hit said altar with a hammer 4. Notice the lack of lightning I tried it twice as WX-78 and the Altar didn't shoot lightning both times if that helps at all.