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Old 03-21-2011, 12:18 PM   #8 (permalink)
EcoModding Lurker
Join Date: Mar 2011
Location: In My Truck
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I think this is a great idea. My old truck sometimes likes to energize the fuel pump just for fun, and it drains the battery. It'd be nice to get some warning when it is in that "mood".

I can imagine unwelcome potential consequences from coupling the raw 12v to the analog inputs of the arduino. I'm not sure voltage dividers would be sufficient. I also want to minimize pin use, and I'd like to free up some pins from the original design.

Thinking about features...

I can see two voltages that would be useful - The running voltage, which would reflect alternator output, etc (call it "running volts", RV). And the lowest voltage from the battery while the vehicle was off ("cold volts", CV).

The CV code would need to ignore the drop in voltage that occurs at startup.

An option could be added to display CV at startup. Maybe it would periodically flash on the display for the first 60 seconds after startup, reducing in frequency over time, and also display on a diag screen?

We might have an option to store the average RV, and flash an alert if it seems low?

It might be neat to have optional code to track a voltage drain over time by monitoring CV. So we might monitor the decrease in CV per hour, and report a voltage drop per hour, or per day.
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