BATTERY MONITOR
This circuit makes it possible to monitor the charging process of a battery. After
constructing the circuit, final adjustments are simple and the only thing needed is a
digital voltmeter for the necessary accuracy. Connect an input voltage of 12.65 volt
between the positive and negative connections of the circuit and adjust the VR1
(10K trimmer) until Led 10 lights up. Lower the voltage and in sequence all other
LEDs will light up. Check that Led 1 lights up at approximately 11.85 volts. At 12.65
volt and higher the battery is fully charged, and at 11.85 is considered to be at its
lowest state. LED 8, 9 and 10 indicate the battery capacity is more than 50%, LED
4 to LED 7 indicate a capacity of 30% - 50% and LED 1 to LED 3 indicate less that
30%. This circuit, with the components shown, uses less than 10mA. Of course you
can adapt it to your own needs by making small modifications. This circuit is set for
DOT mode, meaning only one LED at a time will be lit. If you wish to use the BAR
mode, connect pin 9 to the positive supply rail, but obviously with increased
current consumption. The LED brightness can be adjusted by choosing a different
value for the 5k6 resistor connected at pin 6 and 7. The diode 1N4007 was
included to protect the circuit from a wrong polarity connection.
