Car battery indicator window clear3/30/2023 NOTE: If you do not require the power saving, you can use a 78L05įrom the datasheets, the AtMega328P current can be dropped from around 10mA to 1mA by selecting the internal 8MHz oscillator, as compared to the external 16MHz crystal. ![]() But, by using a low drop out regulator like the LP2950 3.3V, this can be dropped to as low as 0.1mA. I opted for a 3.3V low drop out regulator.Ī standard 7805 regulator has a quesent current of around 20mA. Running the AtMega328P at 5V, uses more power than running at 3.3V. I used the following methods:īy pressing the button, the LED display is turned on, and automatically turns off the LEDs after 30 seconds. There are several ways to reduce the overall power used by the circuit. LED Display - Adjustable maximum voltage level - Adjustable minimum voltage level - 3 Adjustable alarms (typically 50%, 30%, 20%) - Alarms to be non-irritating, and have a mute function - Minimum buttons - Low power consumptionįor my design, I opted for the AtMega328P micro. The aim was then to design a battery indicator with the following specifications: With a standard LM3914 battery monitor, the battery monitor itself will drain a 7Ah battery in about 46 hours. Lastly, the current drawn by circuits I have tested, ranged between 45mA and 150mA. However, add a second or third warning, this can become a problem. Using pots for adjustments, is the normal method used. If a low level warning is also required, this will then result in three voltage levels to be monitored. The biggest difference is the required minimum and maximum voltage to be displayed. ![]() However, each person wants something a little different. With the use of 12V batteries becoming more popular (typically the 7Ah sealed lead acid), I have been requested several times to build a state of charge (SOC) meter displaying the voltage on LEDs.
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