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Author Topic: 4A through the Duemilanove's Vin?  (Read 502 times)
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Hi,

I got a Duemilanove which is meant to be powered by a 12V/4A lead-acid battery.
I've got a 160mA motor hooked up, switched by a 400mA mosfet and a 3,6A (!) car horn switched with an 18A hexfet.

All I wanna know is, if my Vin can deliver the 3,8A needed by the actuators, or do i need to put in a relay? I'm not gonna try it since my last arduino got fried for unknown reasons and I don't wanna experience that again..

Cheers
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All I wanna know is, if my Vin can deliver the 3,8A needed by the actuators

Unlikely.  There is a diode inline with the Vin pin that is likely only rated for 1A.
As a general rule, don't power external devices via the Arduino.  Power them separately, and control them via the Arduino.
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You can't power those devices from the Vin pin of the Arduino, but you can power them from the 12v battery that powers the Arduino. As you've described it, you don't need a relay.
« Last Edit: September 07, 2011, 05:01:11 pm by dc42 » Logged

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As stated you can't power the 4 amp circuit via the Vin pin. However you can power both the arduino and the external motor circuit with your one 12vdc battery. Just run one pair of wires (+12v and ground) to the arduino and either plug it into the external power connector or the Vin and ground pins on the shield connector. Then run seperate (heavier gage) power and ground wires to your external motor/driver components. No relay required.

Lefty

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4A is way beyond the spec of the Vin header connector let alone the diode or regulator.  It might even damage the traces on the PCB - definitely keep high currents separate!
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