3/1/2024 0 Comments Arduino dc battery monitor![]() ![]() The ATmega328P "measures" the voltage at the junction of R1 and R2 on its analogue input pin A3. On the controller's input has proved to be necessary in practice. ![]() The input voltage can be up to 28 volts before the voltage at the junction exceeds the microcontroller's 5 volt limit and no over-voltage protection The fairly high values are chosen deliberately so as to draw very little current from the battery. Please note that I'm unable to supply the source code for the Windows executable.ĭownload Windows Executable Battery Voltage PlotterĪ potential divider consisting of a 100K resistor and a 22K resistor (R1 and R2) is connected across the incoming 12 volt supplyįrom the car's auxiliary socket. Highcharts licensing requires me to point out that Highcharts software is not free for commercial use but free distribution and use is allowed under their However, for convenience, I wrote a dedicated Windows program to convert and display the data automatically The voltage readings, together with the date and time are saved in comma-separated variables (CSV) format so should be reasonably compatible with Microsoft Excel. So I built this little unit which plugs into the car's 12 volt auxilliary socket to monitor the battery voltage and write the readings to a MicroSD card every five seconds. Power a dash cam based on whether the engine is running.Īs there is no simple way to determine if the ignition is "on" (wasn't life simple in the old days!), this unit started life as a way to try to find - and record - a battery voltage that would satisfy the requirement to automatically switch the dash cam on and off.Īlso, as my car had suffered a failed battery after only two years, I wanted to monitor its smart charging system anyway. My car is fitted with an (eco-friendly?) engine Start-Stop system and Ford's quirky "smart battery charging" both of which make it difficult to
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