An alternator works in conjunction with a system of belts. If a belt is not turning freely, the excess friction will cause the belt to heat up, which produces a burning rubber smell. If you catch a whiff of a smell similar to that of an electrical fire, this could indicate that the belt is slipping on the alternator pulley, causing poor alternator output. Tightening the belt often does the trick. If the situation arises where tightening your belt does not fix the strange smell and alternator output, we recommend having your alternator evaluated by a professional.