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Topic: Power Supply (Read 1 time) previous topic - next topic

jag3498

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

Grumpy_Mike

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.

jag3498

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

CrossRoads

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)
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

With 5, you're just heating up the regulator. Try 3 first direct to 5V and see how you do.
DO NOT CONNECT BACKWARDS!
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

jag3498


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.


jag3498

Could i connect an 9 volt battery that way?

Grumpy_Mike

#7
Jun 07, 2011, 10:34 pm Last Edit: Jun 08, 2011, 12:38 pm by Grumpy_Mike Reason: 1
Quote
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.

jag3498

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

Grumpy_Mike

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

jag3498

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?

Grumpy_Mike

Quote
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.

jag3498

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

CrossRoads

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.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

justjed

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.
... it is poor civic hygiene to install technologies that could someday
facilitate a police state. -- Bruce Schneier

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