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Hello,

I've seen the arduino mega max voltage is 12v, I have a 12v acid battery, obviously it give about 12.6v, for best performance (I dont want any heating issues) should I add a 12v voltage regulator or is the 12.6~13v not really an issue?

thanks.
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http://arduino.cc/en/Main/arduinoBoardMega

"Input Voltage (recommended)   7-12V
Input Voltage (limits)                   6-20V"

Not a problem except for heating.

http://arduino.cc/en/uploads/Main/arduino-mega-schematic.pdf

The schematic shows the regulator as being MC33269D-5.0.

The datasheet (http://www.mouser.com/ds/2/308/MC33269-D-77885.pdf) gives a chart of how much power you can suck through the regulator at various voltage differentials.  If your input is 12.6V (7.6V differential) you can only draw about 350 mA at a 25°C ambient temperature.
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My question is how much would it heat and do you think it might cause any problems.

I want to have my arduino mega connect to the upcoming shield seeeduino gprs shield V2, so I do need (I guess) a pretty large current at some times (broadcast).
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if u just want to reduce heat you could eventually use a 7808, this one would warm up too then but atleast ur ardu much less.
voltage regulator like 7812 would not work for those 78XX as their input has to be like 2V higher than their output.
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but do you really think I need to do that?
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but do you really think I need to do that?

As I said:  "you can only draw about 350 mA at a 25°C ambient temperature."

If you need more than 350 mA total (Arduino + shield) then you need a different solution.  The Arduino draws about 50 mA with nothing connected (I usually allow 100 mA for the Arduino alone).  Does the shield draw more than 250 mA ever?
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