With the magneto-storage battery combination, it is possible to obtain a few small lights at any time, whether the engine is running or not, and the engine is always ready to start on the first “over” with the storage battery and a good mixture. If a magneto is not used, difficulty is sometimes experienced in obtaining a suitable source of charging current, as many localities do not possess direct current plants. Batteries may be charged from the direct current exciter in an alternating current station, or may be charged by an alternating current rectifier such as is used by automobile garages. The principal objections to the storage cell are: inconvenience of charging; sulphating of cell when standing without a charge; ease with which the cell is ruined by short circuits; the damage caused by the spilling of the electrolyte; and the fact that the cell gives no warning of failing or discharged condition. Since the composition of the plates depends on the direction in which the current flows through the cell, it is obvious, that an alternating current which periodically changes its direction of flow will first charge the plates and then discharge them alternately. The result of an attempt at charging with alternating current would be that the plates would be in the same or a worse condition in a short space of time than they were at the beginning. In charging a storage cell care should be taken to determine the character of the current, especially when the cell is to be charged from a magneto. When under charge, the cell is connected to the charging circuit in such a way that the current flows backwards through the cell or in a direction opposite to that when the cell is discharging. (86) Care of the Storage Cell. The storage battery should never be left in an uncharged condition with the acid electrolyte in the cell, for the solution will quickly attack the uncharged plates and combine with them to form lead sulphate. As lead sulphate has a high electrical resistance and is insoluble in the electrolyte the sulphate coating will reduce the output or if present in excess, ruin the cell. The sulphate appears as a white coating on the surface of the plates. The only remedy for this condition at the hands of the average engine operator is a prolonged charge, or over charge, at a slow rate. There are several chemical processes but they are too complicated for the average man. As sediment collects on the bottom of the battery jars, and is liable to cause a short circuit, the plates should be held about half an inch from the bottom of the jar. Care should be taken that the cells of the stationary type of battery are kept dry and clean. Do not allow dirt to drop into the solution as it is liable to destroy the cell.