Automotive batteries typically have one of three types of connectors. In past years, the most common design was the SAE Post, consisting of two lead posts in the shape of truncated cones, positioned on the top of the battery, with slightly different diameters to ensure correct electrical polarity.

The "JIS" type is similar to the SAE but smaller, once again positive is larger than negative but both are smaller than their SAE counterparts. Most older Japanese cars were fitted with JIS connectors. You must ensure that when you are buying a new battery that you know which connectors you have. One must also look at the orientation of and which side of the old battery the connectors are on, otherwise you might find that if the connectors are oppositely oriented that the battery cables will not reach the new battery connectors.

General Motors, and other automobile manufacturers, have also begun using side-post battery connectors, which consist of two recessed female 3/8" threads into which bolts or various battery connector adapters are to be attached. These side posts are of the same size and do not prevent incorrect polarity connections.

L connectors consist of an L-shaped post with a bolt hole through the vertical side. These are used on some European cars, motorcycles, lawn and garden devices, snowmobiles, and other light duty vehicles.