I recently purchased a car black box camera that records HD video and audio as you drive  along with a built-in GPS and accelerometer.  This model also has a parking mode that stays active while your car is parked.  Any motion in front of the car or vibrations trigger the event to be recorded.  Because I live on a narrow street it is only a matter of time till someone comes along and takes off my side mirror and this camera is meant to catch the incident on video.

Unfortuantely, a camera that is active while parked can drain the car’s battery leaving you stranded.  I wanted a device that would continiously monitor the car’s battery and shut off the camera if the voltage dropped too low.  I bought this product from the local electronics shop and installed it.  Three days later my car wouldn’t start. Back to the drawing board.

Introducing Carduino BatMon – the arduino for your car.

Kevin, Anool and I have been working on a little Arduino compatible board that can monitor two voltages (through a precision resister voltage divider) and shut off a solid state relay if the voltage falls below a selectable value. There’s also an optional display board (shown here displaying the supply voltage). If you don’t want to use the display, the row of pins is a handy breakout of many of the unused Arduino pins.

Requirements:
+ Switch a 12V 1A load (larger loads may be switched with a larger external relay)
+ Arduino compatible
+ Power supply compatible with a noisy car electrical environment (8 to 15V)
+ Dual inputs for an always on battery voltage and an ignition switched voltage
+ Ability for the user to easily switch between various low voltage cuttoff points
+ Optional real time battery voltage display
+ Optional timer mode (Switch off load after XX hours)

Drop by the forum for more information of this project as it evolves.