the voltage drop across the load the greater the number of diodes which conduct and the greater the number of leds which are illuminated accordingly the bar graph display indicates the state of charge of the battery application_number US 90350392 A description to determine the surplus power of a conventional storage battery it is possible either to measure the specific gravity of electrolyte or to measure the internal resistance of the battery the latter method is much easier the present invention is described in detail in company with attached drawings as follows a switch device sw101 which may be a solid state or electro mechanical type switch device provided for testing an open or closed circuit between the charge and storage battery b101 display circuit d101 which may be a digital or continuous analog level type display for providing a direct or numerical output in response to an input signal charging element z101 connected in series with switch device sw101 the series connected switch sw101 and charging element being connected in parallel across the positive and negative electrodes of storage battery b101 the selection of possible charging elements includes varistors or other conventional components with inductance and resistance or equivalent charging properties including thermo electric charge motor charge or lighting charge manual operating switch m101 connected to.