View Full Version : [Question(s)] Powering an Arduino..

07-29-2008, 08:48 AM
Ok, so heres a quick question. I know that the Arduino runs on 9v of power, what happens if I hook up say, a 9.6v battery? Should I put a regulator inline somewhere, or will the extra .6v not matter enough to effect it.
Also, I know there is a formula to calculate battery life bases on MaH and draw, but I don't know what it is. Anybody know?

07-29-2008, 09:03 AM
I haven't dealt with the Arduino yet, but I think it's pretty safe to say that it won't matter if you use a 9v or a 9,6v battery, there's most likely a voltage regulator on the board since almost all microcontrollers work on lower voltages ( 5V, 3,3V, 1,8V, ...)
Okay so I looked at wikipedia and found this: "Each board includes at least a 5-volt linear regulator (http://en.wikipedia.org/wiki/Linear_regulator).." so you're safe :happy:

The formula you're looking for is Q=I*t or capacity = current * time.
A battery of 1000mAh has a capacity of 1Amp for 1h, better said, it could supply 1000mA (1A) for 1h theoretically.

So, if you have a 1000mAh battery, with a current draw of 0,5A, it would last two hours. With a current draw of 2A, it lasts half an hour.

So much for the theory.
In practice, it's a lot less. A battery can only be used for a certain percentage of it's capacity, until it's voltage runs too low.
What that percentage is, depends on the type of battery used.

A lead-cell battery for example can survive a much deeper discharge than a niCad, and a LiPo must not drop below 3.0v (3.2 to be safe actually)

Hope that helps

07-29-2008, 09:35 AM
Specifically, the regulator on the Diecimila, the most common full-on board now, has a 20v DC max limit, but you'll see the regulator overheat at much more than 12v DC. Under no circumstances should you go above 18v, but even that's asking for trouble.

The chip and board itself draws next to nothing. It's really more about what you have plugged into it for how long you can expect it to last. Ideally you'll put an ammeter on your power supply and get a good idea of what your real current draw is and then you'll be able to calculate battery life (as ScuD observes) much more closely.

07-29-2008, 03:00 PM
Thanks for the info guys! I was pretty sure I was safe, but better safe then sorry!

07-29-2008, 03:04 PM
You bet! The blue magic smoke isn't good for your health

07-29-2008, 03:30 PM
Depends on what its comming out of.. :p

07-29-2008, 03:33 PM
Sort of explains the bright colours in your avatar a bit better, though :p

07-29-2008, 03:34 PM
or me afro..

07-29-2008, 03:36 PM
You look just like my neighbour. Only he doesn't have a beard.And he doesn't go fishing.

What's that smoke here? Ooh hey, butterflies!

Wiiii !

07-29-2008, 04:02 PM
Lol I was baiting a hook..
Heres a more manly picture of me..
And the thread jack continues.. :)

07-29-2008, 04:21 PM
If you're not letting the magic smoke out of components, you're not inventing.

07-30-2008, 04:42 AM
Inventing what? a microprocessor-powered bong? :veryhappy:

07-30-2008, 05:25 AM
^ [bonks ScuD]

07-30-2008, 05:42 AM
uhm.. you what me? :confused:

07-30-2008, 06:06 AM
bonk, noun meaning "a blow to the head" or "a hollow thud" [so many places I could take that but won't]


I tend to use it as a verb. Sue me.

[edit] Oh - there it is as a verb: bonk, bonked, bonking, bonks To strike or cause to come into contact... Close enough.

07-30-2008, 07:55 AM
Aah, okay.. didn't want to misinterpret that one.. pfew!

07-30-2008, 09:29 AM
Aah, okay.. didn't want to misinterpret that one.. pfew!Don't feel bad, I had to look it up too:rolleyes: