[plug] battery / solar powered monitoring system

Nick Bannon nick at ucc.gu.uwa.edu.au
Thu Mar 29 15:53:33 WST 2012

On Thu, Mar 29, 2012 at 02:48:31PM +0800, Onno Benschop wrote:
[HTC Desire, 3.7V lithium cell, 1400 mAh]
>    - Running time, max 14 hours
>    - Usage, 100mA per hour
>    - 14 days is 336 hours
>    - Usage over 14 days is 33Ah
>    - 20% fudge, is 40Ah

You've got a working solution here, Luke. Depending on fudge factors,
that's almost low enough for a pair of cheap 1.5W solar battery
maintainers to keep up with. If you replaced the basic USB charger
with an efficient switching charger that only needed about 40mA at 12V,
it would be: on average you'll get the equivalent of 4-6 Peak Sunlight
Hours at 2*1.5W, per day:


...at which point you could make do with a cheaper car battery that only
needed to last a few days of poor light at a time and not be flattened

You could add a battery monitoring LED in view of the camera, or a whole
bunch more fairly-power-friendly input/output/monitoring with something
like: http://arduino.cc/en/Main/ArduinoBoardADK

Other phones, careful software that kept the screen off, perhaps uploaded
photos in 10 minute batches instead of keeping the 3G connection open
constantly... could help. So - what software will you be using?


   Nick Bannon   | "I made this letter longer than usual because
nick-sig at rcpt.to | I lack the time to make it shorter." - Pascal

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