I recently fitted a new Exide 017TE battery (100 Ah, 900 CCA, though that's probably irrelevant to my question). On one side there's a tiny rubber "button" (stopper), which can be pulled out. So far I haven`t pulled it out, because I don't know what it's for/what purpose it serves.
Could anyone please clarify what it's for and whether I should leave it in / take it our? (Something to do with ventilation, I think.)
Could anyone please clarify what it's for and whether I should leave it in / take it our? (Something to do with ventilation, I think.)