House Battery

Most 12 volt batteries are not true deep cycle batteries. Most 6 volt golf cart batteries are true deep cycle batteries. For house batteries, it is better to have deep cycle batteries. It is true that if one of the 6 volt batteries goes bad, the pair will no longer function as a 12 volt battery. Also, in most cases, two 6 volt batteries combined to make one 12 volt battery will have considerably more amp hour capacity than one 12 volt battery. And, unless the 12 volt batteries are very large, two 6 volt batteries will have more amp hour capacity than even two 12 volt batteries. There are large 12 volt batteries that would have more amp hour capacity but they will probably not fit in the battery box that was designed for two 6 volt batteries.