PURPOSE: To provide a loading method of a storage battery with a reserve cell to an engined automobile which can exercise the function of the storage battery with a reserve cell in a good condition.

CONSTITUTION: This storage battery with a reserve cell has three cells A1, A2, and B in the three cell series connection, and the main cell A1 of a large capacity, and the main cell A2 of a small capacity are connected in series, while the main cell A2 of the small capacity and the reserve cell B are connected in parallel through a switch, arranging in the direction of the long side of the battery in the order the main cell A1, the reserve cell B, and the main cell A2. Such a storage battery with reserve cell is loaded by making the main cell A2 with the small capacity to the engine side, and the main cell A1 with the large capacity to the reverse side. As a result, a condition that the life of the main cell A1 with the large capacity is deteriorated at first can be prevented, and even though the main cell A2 with the small capacity is deteriorated at first, the engine can be started by getting the help of the reserve cell B. Consequently, the function of the storage battery with reserve cell can be exercised sufficiently.