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I was driving home from work the other day when I glanced at my fuel and temperature gauges, which currently do nothing, and suddenly thought, "man...I could totally put those to use now!!"
So today I found the wires that go to the ex-coolant temp and fuel level senders. When I ground the former, it draws 220mA and the coolant temp gauge pins to the max. When I ground the latter, it draws 117mA and the fuel gauge slowly moves to full. This will be incredibly simple to do....simply control current with an NPN transistor on each, feeding each a calibrated PWM.
Actually...I will use opto-isolators to keep the 12V accessory side isolated from the 72V pack side that the Arduino will be in bed with. However, I do not know what their characteristics are compared to regular old transistors. Something tells me they take a lot more current to trigger/switch than transistors which take hardly anything. I may have to up the Arduino's juice with a transistor to trigger an opto-isolator. I must acquire one ASAP and do some playing.
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