Parents bought a 2012 non-retina MacBook in India (where they are ATM). I got an email saying the battery vibrates when the MacBook is plugged in. Maybe something to do with it not being earthed; I think they use two-pin plugs over there.
Anyone else have a tingly MacBook battery? Would it clear up in the uk where we have three pins? Is it dangerous or bad for laptop? Parents are bit concerned.