next topic »

[on:]

Hi,

I am planning to operate the Arduino via batteries and I need to use the power Jack not the Vin and ground as I am mounting a USB Host shield on to the Arduino.

Please explain or provide me  the tutorial for making the circuit for such a thing and how to make a connection to the Power jack. What kind of items I would require and how to combine them up ? How much volts are required from the battery ?

BR,
Vik

[Reply #1 on:]

Lots of information here:

http://arduino.cc/playground/Main/IntWithHW-PwrSup

[Reply #2 on:]

Please explain or provide me  the tutorial for making the circuit for such a thing and how to make a connection to the Power jack.

I don't understand your question.  Vin and the Barrel jack are essentially the same node.  So whatever works on Vin will work on the barrel jack.  Physically, it is a 2.1mm jack with the center pin being positive.

[Reply #3 on:]

You also need the equivalent of 5 AA batteries if providing power via the 5.5/2.1mm center positive barrel jack.
The reverse protection diode and the 5 V regulator eat up the excess voltage.

Get a cable like this
http://www.allelectronics.com/make-a-store/item/CB-204/2-CABLE-W/2.1MM-COAX-POWER-PLUGS-BOTH-ENDS/1.html
cut off one end connect the wires to your battery pack.

Or, just 3 AA batteries connected to the 5V pin will do the job for you.

[Reply #4 on:]

All the answers will work but in my opinion they are overly complicated.  Just hook up a 9 volt battery to a 2.1mm power jack.  You can get both the 9volt batt connector and the  2.1mm power jack at radio shack. Or you can order them from Jameco or Digikey or where ever.  Wire the center positive on the power jack and plug it in.  You're done.  Now if you want something that draws power from the mains and plugs into the board get a wall wort from radio shack or jameco or where ever and you are done. 

I actually keep a supply of wall worts just for this purpose. As they teach in the Boy Sprouts "always be prepared to start a fire anywhere."

[Reply #5 on:]

Just hook up a 9 volt battery to a 2.1mm power jack.

Internally these batteries are built from 6 miniature 1.5V cells connected in series and they're designed for long term use in ultra low power devices. They are popular because of form factor and availability, but not a good choice for a microcontroller project. Due to the limited current capacity and the higher than desired voltage (9V as opposed to 5V or 3V3) they are extremely inefficient as a power source for Arduino. Using a 9V battery for test when nothing else is available is one thing, but designing for it is just silly.

[Reply #6 on:]

Just hook up a 9 volt battery to a 2.1mm power jack.

Internally these batteries are built from 6 miniature 1.5V cells connected in series and they're designed for long term use in ultra low power devices. They are popular because of form factor and availability, but not a good choice for a microcontroller project. Due to the limited current capacity and the higher than desired voltage (9V as opposed to 5V or 3V3) they are extremely inefficient as a power source for Arduino. Using a 9V battery for test when nothing else is available is one thing, but designing for it is just silly.

Maybe you didn't read the OP's remark about his desire to run his Arduino from batteries.  So you don't think that running an arduino off a 9-volt is not a good idea.

I am not sure about the use of a 9 volt not working. I did a quick google search on how much an arduino draws.  The result I got was 18.7mA.  And I found that an   Alkaline 9volt batt has 565 mAh and a lithium has 1200 mAh.  So you can expect to get something like 30 to 65 hours of use.  Now if you are sourcing current out of the pins it will be much less.  But that goes to what I said about getting a wall wort.  But it really depends on the usage as to how "silly" it is to run your arduino off of a battery.  If you are going to run your arduino for a couple of hours and then shut it down it's not silly at all.  And if you are building a circuit that will run say in your fishing boat it's not silly at all.  There are far to many unknowns to say it's silly.

[Reply #7 on:]

Maybe you didn't read the OP's remark about his desire to run his Arduino from batteries.  So you don't think that running an arduino off a 9-volt is not a good idea.

There are countless posts from people using 9V batteries, wondering why their projects don't work.  Sure an Arduino by itself will last a long time on a 9V, but most projects add in a few LEDs or Motors which draw far more current than the Arduino.

Alkaline 9volt batt has 565 mAh and a lithium has 1200 mAh.

Capacity is directly related to how much current is actually being drawn.  Take a look at this datasheet from Energizer:
http://data.energizer.com/PDFs/522.pdf

1.  It states 9V types are only good for Moderate Drain devices, like a clock.
2.  As more current is drawn, the milliamp-hours goes down, fast.
3.  Voltage drops below 7V (minimum for the on-board regulator to be stable), very quickly.

#3 is important because the 9V will have capacity left, but the output voltage will be too low to be usable.

[Reply #8 on:]

The arduino really lends itself to running off 3 AAs, 3 Cs, 3Ds, at 4.5V nicely, without dissipating a lot of battery power across the reverse protection diode or as heat in the regulator. Connect the batteries to the 5V and Gnd pins on the power header.
Or a 3.7V LiPo to the same pins if higher voltage is not needed elsewhere. (4.2V charged, 3.7V when it gets low).