logger power , sleep power

by bethesdakid on Thu Nov 15, 2012 10:38 pm

logger power stays ~42,7ma at 10 sec cycle time to ~42.7ma / 60 sec cycle time to -42.7ma at 10min cycle time. hence no savings when minimizing data logging, The power down function only reduced power to ~36.8ma. which is a 14% saving... not enough when you are logging a DHT sensor/logger system with a 9V battery for 3-5 months not 40 hours not even 2 days...

UPDATE 10-2013 :

the WDT and AVR sleep reduces the current to 10-11 ma. Is there a MCU board which connects to the logger and programed from a pc that reduces this to below 1 ma when in a power down mode using 4 AA (4.6V) power….

Final update 1-8-2014... the fully assembled logger takes less current than the old unit. The new one has the LED disabled to reduce the current to about a mill. with a 1511 cycle for statement to sleep for 4 hours, the system was installed in the field. I will be retrieved in 2 months.
Last edited by bethesdakid on Wed Jan 08, 2014 9:17 pm, edited 2 times in total.
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Re: logger power , sleep power

by adafruit_support_bill on Fri Nov 16, 2012 5:22 am

There are some notes on WDT usage here: http://letsmakerobots.com/node/24536. But one of the bigger problems with trying to save power on the Arduino is the 7805 linear voltage regulator. With a 9v power source, you are only about 55% efficient. You might consider using 4x NiMh (4.8v) as a power source, or using a more efficient 'buck' regulator such as this one to bypass the 7805:
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Re: logger power , sleep power

by pgrunwald on Sun Dec 09, 2012 5:33 pm

How does this method compare to using this: http://code.google.com/p/narcoleptic/ ? Does one have advantages over the other?
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Re: logger power , sleep power

by adafruit_support_bill on Mon Dec 10, 2012 6:26 am

How does this method compare

The narcoleptic library looks like a good one. But it doesn't address the fundamental inefficiency of the 7805 voltage regulator. With a 9v source, you are throwing away almost half your available power. To maximize battery life, you would want to combine your low-power sleep strategy with a more efficient voltage source.
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Re: logger power , sleep power

by pgrunwald on Mon Dec 10, 2012 10:56 am

Thank you, do I have to use NiMH or could I use Lithium? (do I have to stay below 5V?).

Thanks,
Paul
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Re: logger power , sleep power

by adafruit_support_bill on Mon Dec 10, 2012 11:11 am

You do want to keep it below 5v. (The absolute max rating for the Atmega is 5.5v). But you can get an Arduino to run on 3.3v, so it would probably be OK running on a single lithium cell. Not sure about the logger though. The on-board 3.3v regulator need some 'headroom' to regulate properly. The other option would be to go with 2 lithium cells and one of these: http://www.adafruit.com/products/1065
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Re: logger power , sleep power

by bethesdakid on Wed Dec 12, 2012 1:10 pm

thanks ada support. :D :D .. I did change to a 4ea 1.2V, 2450mAh battery producing 4.6V, 2450 mAh supply that reduced current of ardun/log w/ DHT 22 that resulted in a current of 20.1 mA. That will extend operating time to about 5 days. Now what can be done to get at least 3-5 months.

UPDATE 10-2013 :

the WDT and AVR sleep reduces the current to 10-11 ma. Is there a MCU board which connects to the logger and programed from a pc that reduces this to below 1 ma when in a power down mode?
Last edited by bethesdakid on Sat Oct 12, 2013 2:13 pm, edited 2 times in total.
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Re: logger power , sleep power

by adafruit_support_bill on Wed Dec 12, 2012 1:27 pm

Although the Arduino may be sleeping, the logger and probably your DHT 22 are still powered. You might consider using something like a MOSFET to switch power to the shield/'sensor only when the processor is awake.

The PIR sensor in the store will detect animal movement: https://www.adafruit.com/products/189
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Re: logger power , sleep power

by pgrunwald on Sat Dec 15, 2012 3:35 pm

Any idea when the shields will be in? they have been on back order for a while.
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Re: logger power , sleep power

by adafruit on Sat Dec 15, 2012 4:27 pm

will be any day now!
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Re: logger power , narcoleptic sleep power

by bethesdakid on Thu Jan 10, 2013 6:08 pm

A test of narcoleptic was done with just the Arduino board and 4 ea 2000 (duracell) rechargable AA batteries. The nominal current was 27ma. Running the narcoleptic (MerlinTheCat) Power-down reduced the current to 19ma. Basically, the Arduino Uno R3 CPU, the Atmega328d, becomes inactive reducing the power consuption. So, the 8 ma reduction only shuts down the ATmega328d.

Other board systems are obviously still operating.

So the questions are:

A. how can the other systems on the board be reduced in power if the Arduino is to operate several times a day with only a DHT sensor and an IR detector ( several = 1 to 4 times) ? what other programs are necessary to do that?

B. This device is to be used with a logger shield. The total operating current is about 43 ma. Hence the shield takes 16ma. Can it be shut down to conserve power? What program will do that?
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Re: logger power , sleep power

by adafruit_support_bill on Thu Jan 10, 2013 6:23 pm

As suggested earlier in the thread, you might consider using a MOSFET to switch power to the shields. This would involve cutting the trace from the 5v pin that supplies power to the shield and switching it via the MOSFET. If you have space left in the prototyping area of the shield, that would be a good location for the MOSFET.

The MOSFETs we carry in the store can be switched with a 5v logic signal. The Arduino can drive the signal high when it is active and let it be pulled low when it goes to sleep.

https://www.adafruit.com/products/355
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Re: logger power , sleep power

by bethesdakid on Sun Jan 27, 2013 11:00 pm

the test without the logger shows that the AA's will run a max of 5 days... need to reduce the power to at least 5ma for 20 days, optimum is 1 ma.
what software will do this?

I have a MOSFET that will be used when I install the logger shield...
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Re: logger power , sleep power

by gordiegii on Sun Feb 03, 2013 1:41 am

You need to modify the existing sketch to turn off the FET(s) before putting the Arduino to sleep and turn the FET(s) back on when it wakes up. Then you _might_ need to re-initialize the logger and/or your DHT 22 before you use them. It sounds like a lot of hassle, but should save a lot of power.

You also might look into using an Arduino Pro. I've heard they use less power. I don't know whether there would be any other ramifications to your project.

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Re: logger power , sleep power

by bethesdakid on Wed Feb 06, 2013 11:54 am

The guru stated that 4ea AA rechargeables produce 4.6V which will reduce the current loss.
Wrong!
First set produced 5.8 V.
Second set was 4.8V

so... with 4.8V batteries,

First, run the UNO rev3 by itself. Check power.
Second, same setup, with Narcoleptic sleep. check power
Third, add Logger, check power
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