A solenoid valve control circuit for operatively connecting a battery to a solenoid to energize the solenoid to actuate a valve includes a coulomb controlling circuit for controllably supplying electric charge to the solenoid in accordance with predetermined criteria.Bellows Seal Valves In a solenoid valve control circuit including a latching solenoid for driving a plunger of a latching-type solenoid valve from a closed position to an open position and from said open position to said closed position when said solenoid is operatively connected to a battery, Balance Valvesthe improvement comprising: coulomb controlling means for controlling a total quantity of electric charge to equal a predetermined value, said total quantity of electric charge being a required quantity of electric charge corresponding to the voltage of said battery and supplied from said battery to said latching solenoid when said plunger is to be driven from said closed position to said open position and from said open position to said closed position,WATER POWER CONTROL VALVE wherein said coulomb controlling means supplies said required quantity of electric charge to said latching solenoid; a decision circuit for producing an energizing signal indicating that said battery is to be connected to said latching solenoid under a prescribed condition; and a solenoid valve drive circuit responsive to said energizing signal for operatively connecting said battery to said latching solenoid to energize said solenoid, and wherein said coulomb controlling means comprises: a power supply voltage monitoring circuit for monitoring the voltage of said battery and producing a signal corresponding to the battery voltage; and a coulomb controlling circuit for monitoring the total quantity of electric charge supplied from said battery to said latching solenoid and for producing a de-energizing signal based on the signal from said power supply voltage monitoring circuit when the total quantity of electric charge supplied to said latching solenoid is equal to said required quantity of electric charge corresponding to said battery voltage. Where a battery is employed as the power supply for the solenoid valve and the solenoid is to be energized for a constant period of time, a problem arises either when the voltage Vcc of the battery is higher because the battery is new or when the voltage Vcc of the battery is lower because the battery is old or deteriorated. More specifically, if the time for which the solenoid is to be energized is selected to be relatively short in view of new battery conditions, then the solenoid will not be sufficiently energized when the battery voltage Vcc becomes lower and the plunger will not be driven to a desired stroke. Conversely, if the time of energization of the solenoid is selected to be relatively long in view of old or deteriorated battery conditions, then the solenoid will be excessively energized when the battery voltage Vcc becomes higher, resulting in excessive electric power consumption and a shorter battery service life.

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