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Author Topic: Batteries, howto make a board that can run a year?  (Read 1766 times)
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I do not know what the boards will be for and which number of boards you plan. Everything of design, assembling and implementation can be outsourced. However this is not cheap either smiley-wink But at least you can trade money for time.
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Learn about sleep modes and if its only to log temperatures run the micro with the internal 8Mhz RC and with clockdiv on, the slower it is the less power it uses, dont put any unecessary always on leds and minimize resistor use.
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CKDIV will only reduce total power consumption if you also lower the voltage. Otherwise you will have to stay awake longer which in turn leads to MORE power consumption. This is because you basically transport the same amount of charge per cycle. However running with CKDIV means MORE cycles for the oscillator. So if you have to lower power consumption decrease voltage as much as possible. Then setup CKDIV to still run stable at that voltage. Alternative option: run with the watchdok oscillator only @128kHz.

Anyway: have a look at the datasheet and turn off whatever you do not need (e.g. serial, A/D converter)
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I did read your topic just now.
But to me it don't seem to be necessary to search for extreme small power consumption.
I am currently working (also in spare time) on a batterieloader for reloadbatteries, based on arduino.
The purpose is to disconnect from power supply (in my case 230 ac) if the load is complete via a optocoupler.
But in your case i would work with solar power (a small surface should do) and reload batterypack (4x 1.2 volt cells do very well for this purpose).
How it would best work in case of solar power supply : that needs some work out, because i also had some problems with to make it all go smooth.
But mainly i think a combination of the solar cell + a constant current source toward the batterypack should do.
In this way it must be possible to build easily a device that works even over a year or even two and weighs less than  1 kg.
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Could you hook up a rechargeable battery to a PV cell and have it trickle charged from the sun during the day? That could help get it to last a bit longer.
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Use a clip on current transformer to steal power from insulated cables in the vicinity of your logger.
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So how about maybe not full custom?
Get some of these
http://ca.mouser.com/ProductDetail/Arduino/A000006/?qs=sGAEpiMZZMs0PWRNvpRp0ARF1Zt0Kmpi
and just populate as little as you need:
socket for atmega168PA, 8 MHz (or llower) xtal, 22 pf caps, 10uF cap.
shield connectors for the xbee & power.
Program the atmegas seperately, plug in to the board.

More power on maximizing battery also
http://www.atmel.com/dyn/resources/prod_documents/doc8349.pdf
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I would omit the crystal. This gives two additional IO pins and reduces power consumption. Instead I would add some quality RTC. This would allow for superior timing. It also would allow to go for deeper sleep modes thus resulting in even less power consuption.

If exact timing is needed the AVR RC oscillator can be calibrated. Since the RTC solution provides a reasonable good reference it is possible to recalibrate anytime exact timing is needed.
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Can you hack one of these to power your project?

http://www.walmart.com/ip/Alpine-Super-Bright-Solar-LED-Plastic-Lights/15994043
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Why not try an Arduino Fio?  I've got one that I connected the SLEEP_ON signal from the xbee to D2 on the Fio and I'm using xbee cyclic sleep mode and putting the fio to sleep waiting on a rising edge interrupt on D2 every 10 minutes.  I'm still working on the software but I'm hoping to get a couple of months from a 1000mAh LiPo battery.
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