which board would use less battery here?

Hi,

Any advice re which board would use the least amount of battery (or have the capability to use the least amount) for the scenario where:

a) Will have a digital input (reed switch) b) Will sleep & use a hardware interrupt from the reed switch to wake c) Will then power up the small RF Transmitter via a digital output d) Then send (using virtualwire) a string of info via the RF Transmitter e) Then sleep again

So I'm willing to get into soldering etc. Would love to have a way to get say 1 year life on a 9V battery here...

Would love to have a way to get say 1 year life on a 9V battery here...

Well it depends on how big your battery is and how often it is woken up but this life time looks unlikely. Most processors in this family take in the region of 30mA when they are awake. The transmitter is likely to be the biggest current hog.

So I'm willing to get into soldering

Soldering isn't going to save your battery, coding is.

From here:http://en.wikipedia.org/wiki/Nine-volt_battery it looks like the highest capacity is lithium, with 1200mAh. If we assume 8760 hours in a year, that's an average consumption of 137uA.

Why the fixation with 9V?

Seems like others are interested in this subject too: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1277637970 http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1277663477 http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1277372516/2#2

Seems like others are interested in this subject too:

Odd that they all have the same name and are asking the same question.
I had children like that, they would ask you a question and if they didn’t get the answer they liked they would ask Mum.
Just a little hint to all posters.
Ask your question only once in one forum, otherwise we all get a bit pissed off with you.

@GregH
Actually this is the wrong processor to be using to make a low powered device, it burns far too much when it is in sleep mode.

What will get you the longest battery life is --

  • Operating the uC at the lowest possible frequency your application can tolerate
  • Operating the uC at the lowest possibly voltage your application can tolerate
  • Proper programming of the sleep modes
  • Efficient power conversion. Unless you use a switching power converter a 9V battery is not a good choice.

(* jcl *)


www: http://www.wiblocks.com twitter: http://twitter.com/wiblocks blog: http://luciani.org

These were all separate questions for me at different parts of my learnings. People on this forum have been great and helped me ramp up. In the first week or of anew technology this really helps.

It's a shame you seem intent on taking the time to audit the history of my posts to show up my inexperience in this area which is new to me. Then followed up by some degrading statements.

audit the history of my posts to show up my inexperience in this area which is new to me.

I wouldn't mind if they were septate questions but they were all the same question. True you used slightly different words but you were always asking about the same thing. When it comes to four threads, it is a bit much.

My apologies to the community

The reason cross-posting is hated so much is because it wastes time, and time is what people give most here. People answer a question on one thread, only to find someone else has posted the same answer elsewhere.

There's no problem about extending a thread until it has drifted so far from the original topic that posting a new thread is the only way to go, but I don't think this topic has gone that far.

As has been pointed out, the only way you're going to get consumption down is to sleep for virtually all of the time, but really, PP3 9V batteries are less than ideal. Three C or D cells would probably do the job better. You need to read up on sleep modes and wake-up interrupts.