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Hi Ladies and Gents

I recently decided that I will investigate the Arduino Sleep Library and see how long I can get an Arduino to run of a single N size1.5v Battery. Yes ! of a 1.5V battery. if you are interested here is what you will need.

1) N size battery

2) N size battery Holder

3) 1v- 3.3v Step up convert ( I used sparkfun unit https://www.sparkfun.com/products/10967 )

4) Pro Mini 3.3v version ( https://www.sparkfun.com/products/11114 )

the code is written in such a way that when in sleep mode the current drawn is around 4.7 uA and when active around 7mA. but to this we need to do a couple of things to insure that not extra power is wasted on regulators and leds.

Step 1: Arduino Pro Mini Modifications

Depending on the Version/ Supplier of your Arduino pro mini board there a few mods needs to be made.

If you bought your pro mini board from spark-fun then you are lucky , there is only one solder jumper that needs to be removed to disable the on-board power regulator.

Sparkfun board

In the photo you will see there a 3 modes marked, de-solder Mod "1" and you are done , this disables the power regulator and drops the current consumption to around 380 uA in normal operation before the sleep code is uploaded

Other version of the board

In the photo attached you need to remove the on-board power led by de-soldering it .the LED is marked "3" and cut a trace on the board to disable the power regulator. see other photo for the trace that needs to be cut.

Once this is done.

You are one step closer ! this is all the hardware modifications that needs to be done.

Step 2: Wiring Setup

The Photo attached illustrate the minimum wiring required to make your Arduino work. my project made use of a cheap china data radio connected to pin 11 and pin 9 for power but you can update the code as you desire.

Step 3: Code

This is the code currently running on my board.

Overview

This code wakes up every hour and reads a analog value on pin A3 and transmits the value over a data link to a remote station. ( you can remove this code and replace with what ever you want to do upon wake-up.)

the code has comments that explains everything the code does and should be easy to modify as you require.

Summary

All battery life predictions that follow is just that predictions and should not be taken as factual but it should give you a good idea of expected battery life.

N size battery is around 900mah capacity.

At 4.5uA of consumption in sleep mode and 7mA in active mode the maths looks as follows.

Lets say you use the device once a day for 1 sec before going back to sleep

you would expect the battery to last 126000 hours total.

126000 - 30% for efficiency losses = 88200 hours.

88200 hours at 1.5v before the step up converter. so divide 88200 by 2 because our device runs at 3.3v

you get 44100 hours effective battery life.

that is 1837 days !!!

NOTE: I know there is better ways of doing this and longer times can be achieved by running at 1.8v but since most sensors run at either 3.3v or 5v I prefer to stick to 3.3v for now and using a N size battery makes the project very small size and the project stays small.


<p>Very good! You might wanna check this board: <a href="https://talk2.wisen.com.au/product-talk2-whisper-node-avr/" rel="nofollow">https://talk2.wisen.com.au/product-talk2-whisper-n...</a></p><p>It's an Arduino with built-in step-up regulator + sub GHz Radio + Flash memory. The idea is exactly the same, but all is built-in a little neat board which can get things working in 5 minutes!</p>
<p>For my Nano 5V it says &quot;4:25: fatal error: VirtualWire.h: No such file or directory&quot;</p>
<p>Hello?</p>
<p>How come it doesn't compile Nano? Does Mini Pro use different code?</p>
<p>You might be interested on this board: https://talk2.wisen.com.au/product-talk2-whisper-node-avr/, which is a low-power version of Arduino with built-in RF, capable of running from a single AA.</p>
<p>nice work. I have similar project with sensors and I will integrate this code for sleep. Easy and simple and understandable code.<br>Can You tell me how to receive struc data on other side ?<br>Thanks!<br></p>
The sparkfun board has the jumper selection as mentioned in the post and no cutting required. But yes removing the reg will work the same . Just reminder you will have power the unit externally to program it
<p>I have looked at a couple of the mini board designs. Looking closely at the Sparkfun board, I don't see the mod you referred to. The generic board I have on hand, isn't exactly the same as you have so it is unclear which trace to cut. Will removing the regulator accomplish the same thing?</p>
<p>Thanks for the quick reply! I like the ability to use a smaller form factor battery. So as I understand it, the voltage regulator draws about 0.3mA when asleep. Doesn't the the step-up transformer draw current </p>
<p>The step up does draw power but alot less then the standard regulator, in my setup i actually have 4 of these in parallel which provides enough current to run the arduino in sleep mode untill the next wake up so then the step does not work at all, another way of doing it is to use a Super cap and charge the cap when the arduino is awake and discharge when arduino sleeps hope this helps </p><p><a href="https://www.sparkfun.com/products/9962" rel="nofollow">https://www.sparkfun.com/products/9962</a> </p><p>https://www.sparkfun.com/products/10068</p>
<p>The step up does draw power but alot less then the standard regulator, in my setup i actually have 4 of these in parallel which provides enough current to run the arduino in sleep mode untill the next wake up so then the step does not work at all, another way of doing it is to use a Super cap and charge the cap when the arduino is awake and discharge when arduino sleeps hope this helps </p><p><a href="https://www.sparkfun.com/products/9962" rel="nofollow">https://www.sparkfun.com/products/9962</a> </p><p>https://www.sparkfun.com/products/10068</p>
Hello , <br><br>It's not not only about efficiency but using all available power , the onboard regulators needs an input of around 5-12v to supply 3.3v plus the onboard regulator also stays on perms malty and even if The device is sleeping it still draws 300 micro amps , but when disabled this drops to 4-7micro Amps . <br>The other reason is size by using a 3.3v battery via a a step up . I am able to use the batter from3.3v all the way down to 1.5 v and still<br>Get 3.3v out
<p>Hello </p><p>I read your instructible with great interest as I have a low power project I am working on. I would like to understadn why you replaced the on board regulator with the step-up converter. Is the stepup that much more efficient?</p>

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