It say you can hook up 7-12V to it. How much ma can it be. I have a 9.6V 600ma Nicd batter, also I have some AA 2450ma and AAA 850ma. So can any of these battery power it as long as I don’t go under or over the V range.
Yes any of those can work. Of course the more limited mah rating of the AAA cells won’t power the board for as long as the others.
I use a 2 series cell lithium poly battery that is probably around 850mah and it works fine for software development for several days between charges, however if I start running a stepper motor or servos it has to be charged much more often.
so what the Ma range to power the Arduino. I don’t know much about Ma so just wondering. I need to look up that kind of stuff. Thanks for your help.
One thing to be aware of is that you have said the batteries were however many “ma”.
But they aren’t!
The battery ratings are in “mah”. As discussed by retrolefty above.
Milli-amps (‘ma’, 1/1000ths of an amp) are a measure of current flow rate.
Milli-amp-hours (‘mah’) are a measure of capacity (flow rate times time).
The difference matters!
If it helps, think of capacity as water capacity, voltage as water pressure, and current as the water flow rate (like gallons per hour or litres per second).
You know that the Arduino wants a bit more than 5 volts to its battery connector.
If you were to hook up six AA’s (in series) you’d get about the right voltage for the Arduino, and about the same voltage as you’d get from hooking up six AAA’s in series.
But the capacity (mah) numbers you give for your batteries suggest that the Arduino would run for about 3 times as long on your AA’s (before the batteries went flat) than on your AAA’s and four times longer than it would run from your ‘9.6volt’ .
The actual current (“ma”) demand from your Arduino (and project) can vary widely, depending on what you are doing and what all you are powering.
A mains “usb charger” (like an iPod charger as one example) usually seems to work well for power away from the computer, if you don’t mind being tethered to the mains.
that_chap gave some good information, but I’ll throw in a small point that may help change newcomer’s understanding: a power source doesn’t “push” the current through the device, the device “demands” current when it connects between two terminals with sufficient voltage.
So if you see an AC/DC adapter that says 500mA, it can support the demands of any device up to 500mA. It’s okay to use a 20mA device on that adapter, assuming the voltage/polarity/plugsize are compatible.
What’s the bare minimum voltage that arduino needs? I have a 7.2v battery that I’m hoping I can power it from so I don’t have to use 2 different batteries (one for arduino, one for everything else).
it depends on what board you’re using; go here: http://arduino.cc/en/Main/Hardware
then select your board that you have, and in the summary section they have recommended voltage inputs and the absolute limits of voltage inputs. (i ended up just using a 9V for my project, worked fine.)
Oh, I didn’t realize that was on the specs page. So I should be good without a separate battery. good to know.