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Device to monitor vehicle voltage

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  • Device to monitor vehicle voltage

    Hi! First time poster!

    I'd like to build an Arduino device for my volunteer ambulance service (approx 80 ambulances) which monitors the battery voltage even when the engine is off. Sometimes, the ambulances can go a week or more without being used, and when that happens, the battery can sometimes die due to the electronics which are always running inside.

    I'm trying to figure out what I need to do to design my circuit to protect against the extreme voltages and currents that I've read can occur during ignition and under other circumstances. I've read that the voltage can sometimes spike to as high as 200V. What do I need in my circuit to accurately read the vehicle voltage (need to step it down below 5V so it's tolerant with the Arduino) while also protecting the Arduino (and the whole circuit) against extreme voltage spikes?


  • #2
    You need to look at a voltage divider.... It is normal in a 12 volt vehicle to plan for roughly 40 volt spikes.. But you have upwards of 200 volt spikes?

    Are you on a 24 volt or higher system? I know some service vehicles have a 24volt system but don't know for sure. I don't know how high a spike on a 24volt system will go.

    A voltage divider will work to bring the range of your "sample" to a measurable range but you may need to incorporate a surge suppressor system so that anything above your measurable voltage is absorbed. You can do a google search to find what will work for you for a surge suppressor but I think the voltage divider is going in the right direction. You can probably find an arduino support forum that will be able to help you better. Another option is looking on Sparks Electronics. They have MANY different kits and I am sure they would have something that would help you out if you can't find a simpler solution.