I used to think that one should connect negative to negative first, because I reasoned that no charge was coming out of the negative terminals. And I don't recall ever observing any adverse effects, so I kept on doing it that way when necessary.
Only now, when Googling how to treat a new car battery, did I read that one is supposed to connect positive to positive first! So I was wrong all this time? What is the reason, then, for + to + first?
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