Power Supply

I was wondering if there is any way to power arduino with two wires from a battery holder. I read something about the VIN pin but did not completely understand it. Would I connect + to VIN and - to Ground? Also, is 6 Volts enough to power arduino?

Thanks, Jack

6 volts is too much to run the arduino processor directly but not enough to drive the 5volt regulator. You need at least 7volts for this if you are going to apply it to the Vin pin.

Thanks for the quick reply. So, would 5 AA Battery's do the trick?

A 3-cell AA battery holder with the + to the Arduino 5V pin and - to ground will work for you.

What other things will you be connecting?

I'd like to find a 3 D-Cell battery holder, that would give plent of juice! The only time I've seen that this is as a flashlight 8)

With 5, you're just heating up the regulator. Try 3 first direct to 5V and see how you do. DO NOT CONNECT BACKWARDS!

So that would provide power without a power supply or USB cable? What if i were to connect backwards? I would probably be connecting just leds, sensors, and maby a buzzer.

Could i connect an 9 volt battery that way?

What if i were to connect backwards

Then there is a good possibility you would fry the arduino. Yes a 9v battery into Vin would work but it would waste power and those square batteries do not have much in the way of current capacity.

So would this power my arduino: 3 AA batters with + to VIN and - to GND?

No as have been mentioned before. If you have three you have to connect it directly to 5V line.

Oh OK. So if i have 7 or more volts, then use VIN. But if I have less use the 5V. So what would be the Best way to power my arduino?

So what would be the Best way to power my arduino?

It depends entirely on what you want to do with the system. What load you have, and how long you want the battery to last.

I would want to run a sensor, leds, and maby a buzzer. I would like the battery to lasts around an hour.

I'd go with 3 AAs, if not enough try 3 Cs, 3 Ds ... Really depends how many LEDs, how much current they are drawing, how long the buzzer is turned for, etc. Who knows, maybe 3 AAAs will get you by. Maybe 4 rechargeables will do at 1.2V each.

Granted, you can’t run down to the local convenience store to buy them, but why not use Lithium-Manganese rechargeables? You can get LiMn 14500’s for about $6/apiece, and they’ll last something like 300-500 charge cycles. Also, LiMn has a high current capacity. The “AW” brand LiMn are more expensive. With 2 of those in series, you get nominally 7.4V.

They’re tight, but the 14500 will fit in a 2AA battery holder. You might have to fiddle with the contacts a bit.

Three batteries is only 4.5 volts, if each battery is 1.5 volts, which most are.

What about one of these: http://www.sparkfun.com/products/341

would I need two?

I am using the uno smd. I found a old broken ac adapter with a right sized barrel plug for arduino. If i cut the cable and striped the two wire could i connect a power source that way? if so what would the required voltage be.

oops. I should of looked there first! would there a way to find out which wire is + and which is - for the barrel plug?