hello, I have a problem and wanted to know if I can help it I need to feed the Arduino and I own battery which is 12 v, but I'm afraid to burn the arduino, wanted to know if the Arduino UNO supports it, the battery is this :http://articulo.mercadolibre.com.ar/MLA-573908466-bateria-black-decker-hpb12-para-hp120-o-gc1200-original-_JM thank you
See Uno specification especially the Technical Specification section. The Uno will accept an input voltage of between 7 and 12 volts.
If you connect a 12V battery to the UNO external power barreljack, the 5V regulator will run hot. It is better to split the extra voltage heat dissipation between two regulators by inserting a lower voltage regulator between the 12V and the input to the external power barreljack. The same amount of heat will be dissipated but it will be divided between the two regulators instead of concentrated in the 5V regulator. The IDEAL input voltage to the external power barreljack is between 7.5V and 8.0 V but neither of those is a standard regulator value so you are pretty much stuck with 9V , (LM7809) which is
much more common than the LM7807 and LM7808, which would be preferable.
12volt on the DC jack is perfectly ok.
Safer on the DC jack, because that input also has battery reverse protection.
12volt is ok untill you are going to draw a lot of power from the 5volt pin.
Like several relays, or an ethernet or other high current shield.
You will know when it's time to do what raschemmel said by feeling the regulator next to the DC jack.
Warm is ok, but a hot regulator could stop and reboot the Uno frequently.
Leo..
Like several relays,
Never a good idea whatever the power supply because relays tend to take too much current from the signal pin let alone the power supply.
The 5volt regulator is designed to supply more than just the Arduino.
12volt on the DC socket just limits the total current to ~150mA because the regulator gets too hot.
Do not confuse supply current with output pin current.
Leo..
Do not confuse supply current with output pin current.
I am not confusing the two.
Since when does a 12V battery cost $753 ?
It's $725 cheaper on Amazon
Do you live in a country where the currency exchange rate to the US dollar is 26:1 ?
We don't really need to know what kind of 12V battery it is if it is really 12V. The only time that would be a factor is if you are using a very high current rated battery to power devices on a breadboard because if by some chance you miswired it or a device shorted internally, (say for example you were probing an LM555 ic and the scope probe slipped off the pin you were probing and shorted the output pin to ground damaging the internal transistor, the power supply , with an almost unlimited amount of current capable, would supply enough current to the shorted ic to make it glow red and spontaneously combust and burst into flame (and smoke) , melting your breadboard and possibly starting a fire. (and yes, I have been there and done that, using a 10A /12V /120W power supply ).
Based on the url, I think it's denominated in Argentine pesos. Still overpriced though
More than double actually:
Currency exchange rate Argentina pesos
raschemmel:
The IDEAL input voltage to the external power barreljack is between 7.5V and 8.0 V but neither of those is a standard regulator value so you are pretty much stuck with 9V , (LM7809) which is
much more common than the LM7807 and LM7808, which would be preferable.
This is where the LM317 proves its utility.
Yeay, but if you're gonna burn heat you're gonna burn heat. Doesn't matter if it's a 7805 of a LM317...
But 12V into the Arduino regulator is fine. Just don't really load the output of the regulator other then the Arduino itself. Otherwise, just get yourself a switched DC-DC buck converter for like $1,- on eBay 
Yeah, but if you're gonna burn heat you're gonna burn heat. Doesn't matter if it's a 7805 of a LM317...
I think the point Runaway Pancake was trying to make is that if you want to obtain the IDEAL input voltage for the UNO external dc barreljack, you can't beat an ADJUSTABLE regulator because unlike the LM7807, LM7808, & LM7809, the LM317 allows you to reduce the output voltage to slightly above the voltage necessary to have 5V on the UNO 5V pin. thus, determining the onboard 5V regulator overhead empirically,
rather than guessing.