Please pardon my electronic noobness, but, is it possible (much less recommended) to connect a battery pack directly to the header pins of an Arduino board so as to power the entire circuit (shields included)? Specifically, I am wanting to mount the battery inside of a case and wanted to leave the barrel jack available only as a backup, not primary, source of power.
I have tested this idea using a quad-AA pack connected directly to the 5v and GND pins and it seemed to work just fine. However, I'm not sure if I just got lucky and if would this also work with a 9v battery? Am I correct in assuming the 9v battery needs to connect to the 9v pin? Will the on-board voltage regulator used by the barrel jack function if you connect a battery this way?
I'm hoping someone here can answer this instead of me frying a perfectly good board. And again, please excuse my ignorance when it comes to these circuit things and the way they get energized with all those electrons.
I have tested this idea using a quad-AA pack connected directly to the 5v and GND pins
4 * 1.5 volts = 6 volts
From the datasheet...
Electrical Characteristics
28.1 Absolute Maximum Ratings*
Maximum Operating Voltage ............................................ 6.0V
*NOTICE: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or other conditions beyond those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Table 28-1. Common DC characteristics TA = -40°C to 85°C, VCC = 1.8V to 5.5V
You probably should not repeat that experiment too many more times.
You can probably get away with directly powering from 3 cells (4.5 volts).
stormbringer:
You could solder the battery pack to the barrel connector so you're using the voltage reg on the board.
lol, came to this post with curiosity at what might get thought up. Love how simple this solution is... now do I dare trust my soldering skills near my Arduino XD
You can also connect the battery to the ground pin (-) and the Vin pin (+) (not the 5V pin). The Vin pin is connected to the barrel connector, so electrically it is the same as using the barrel connector.
First, I have decided to ditch the AA's and go with one 9V cell for power. After KE7GKP mentioned how 6v is an odd-ball amount which may give me more problems, I'm okay with this prototype using a 9v battery instead.
Because of some esoteric electron law that made my brain hurt, I thought I remember it mentioned that the Minty Boost gets better performance from AA's than a 9v. Am I correct in originally thinking that using x4 AA's would have given me more amp-hours than a single 9v?
Thanks for the suggestion theepdinker, I also would still very much prefer to NOT solder any wires onto the Arduino board directly, so I just wanted to double-confirm that it's safe for me to connect a 9v cell directly to the "VIN" header pin on the Arduino board so as to take advantage of the regulator?
To answer CrossRoads, I am using a Duemilanove and the full-size Ethernet shield (with SD card). Not sure on the exact design specs of everything, but, using a stable bench power supply as input, a quick amp check from the multimeter showed around 180mA current draw during idle operation (i.e. not sending any packets) for the Arduino and shield along with a single LM335 temp sensor.
Oh yeah, don't know if this makes a difference with all of this, but I got a jumper from the 3.3v header pin to the AREF input for stable temp sensor values.
Input Voltage (recommended) 7-12V
Input Voltage (limits) 6-20V
So isn't it bad to use less than 6V as stated with "4 AAA or AA NiMhs (nearer 4.8 - 5V)"?
With 4 rechargeable your going to connect directly to the 5v rail and bypass the regulator. The atmega chip itself is rated 4.5 - 5.5v at 20mhz and is rated down to 1.8v at 4mhz though stock brown out detection is just under 3v with the default fuse settings. That said plenty of people run them at 16mhz and 3.3v myself included.
Or you can get cell phone chargers that provide 5v USB power. I bought the EZOPower 5000Mha from Amazon, because it had a relative large capacity, and it had 2 USB out ports, so that eventually I can wire up servos to one USB port and the Arduino to the second: http://www.amazon.com/gp/product/B004I0H9MU/ref=oh_details_o01_s00_i00. The only downside was it didn't have a USB B port as one of the options for cable out, but I have several USB B cables lying about.