How can you determine positive and negative to hook up car battery?

Answer 1

Answer 1 - Automotive Battery Terminal Polarity DeterminationDepending on the brand and model of battery, there could be one or more ways to determine polarity of the terminals. Some batteries may have only one identifier method, while another battery may have a different identification method, and some batteries may 2 or more symbols embossed into/onto the battery top next to each of the terminals.

Here are the battery terminal identifiers I have seen over many years:

• A plus symbol [+] embossed into the battery top next to the positive terminal,
• A negative symbol [-] embossed into the battery top next to the negative terminal,
• An abbreviation [POS] for the word positive embossed into the battery top next to the positive terminal,
• An abbreviation [NEG] for the word negative embossed into the battery top next to the negative terminal.
• And on some batteries, although they MAY look the same, the diameter of the positive and negative terminals will be different, with the positive terminal being just barely / slightly larger in diameter than the negative terminal.
• A DC voltmeter can be used to determine terminal polarity.

Answer 2 - Battery Cable Polarity DeterminationOn some cars a red cable denotes positive or the terminal has + or pos stamped into it. If you are presented with two cables of the same colour, the one connected directly to the car body is usually the negative cable, and the cable that goes to the fuses is the positive. BEWARE vehicles manufactured before 1970 may have reversed polarity, with the positive cable going to the body and the negative going to the fuses.