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Topic: How many / What kind of batteries to use for this? (Read 773 times)previous topic - next topic

MonroeD

Apr 25, 2011, 03:42 pm
http://www.sparkfun.com/tutorials/199
This RGB LED wants 650mA per channel, and anywhere between 9 to 30 volts.

It works fine plugged into a 9V wall adapter, but I need to make it powered by batteries.
Would a series of C batteries work?  If so, how many?

Thanks.

TeslaFan

#1
Apr 25, 2011, 04:54 pm
If only there were a magic formula to figure out how many 1.5 volt batteries it would take to equal 9 volts.

Oh! There is! 9 divided by 1.5 equals 6! Take that, Fermat! I'll take that Nobel Prize now, thank you.

Now, as to how long the batteries will last, you'll have to google for that, dividing the total mAh of the batteries by the load of the circuit.
Linux and Arduino, two great things that go great together!
http://www.roboticcore.com

AWOL

#2
Apr 25, 2011, 08:13 pm
Quote
dividing the total mAh of the batteries by the load of the circuit

Not quite that simple - a D cell could be rated at 14Ah, but try that as 14 amps for one hour.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

retrolefty

#3
Apr 25, 2011, 08:25 pm

Quote
dividing the total mAh of the batteries by the load of the circuit

Not quite that simple - a D cell could be rated at 14Ah, but try that as 14 amps for one hour.

Quite true. mAh ratings are often a 'marketing' specification. Unless the spec is accompanied with discharge rate and temperature one should take them with a grain of salt.

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