[plug] battery / solar powered monitoring system

[Onno Benschop]

You could probably do the following:

   - Set-up your contraption with the standard battery fully charged.
   - Run it until it powers off - you'll now when that is because you won't
   get any more images.
   - Based on the battery capacity of the battery in your phone you can
   then calculate its discharge rate in milli-amp per hour.
   - Based on how long it needs to run, use a battery of the appropriate
   total amperage connected to a 12v USB charger to charge your contraption.
   - You'll have a loss in efficiency associated with continually charging
   your phone, alternatively, see if the phone will run without its own
   internal battery, just running of external USB power. In that case, just
   power it from the external battery.

Likely you'll find numbers something like my HTC Desire (which doesn't run
without an internal battery - I tried) :

   - Battery, 1400 mAh
   - Running time, max 14 hours
   - Usage, 100mA per hour
   - 14 days is 36 hours
   - Usage over 14 days is 33Ah
   - 20% fudge, is 40Ah
   - 12V SLA Battery available from Altronics #S5113, $165 per battery -
   trade price, 4kg each


On 29 March 2012 11:56, Luke John <luke.john at osmahi.com> wrote:

> Hi PLUGgers,
>
> I am looking at setting up a monitoring system using a phone (probably
> android).
>
> The phone would be taking ~10 photos every minute and sending them
> over a 3G connection (preferably more if battery could handle it,
> possibly some video).  It would only be operating during daylight
> hours. It would also not have access to mains power.
>
> The best solution for power I've been able to find so far for powering
> the phone would be using a solar battery maintainer to keep a 12 V
> battery charged and hooking up the phone via a car charger.
>
> Issues with this solution are; I wouldn't be keeping track of battery
> levels, and it possibly wouldn't provide enough power.
>
> Does anybody have any suggestions for powering the device, given that
> it doesn't need to be solar as long as battery replacement was
> fortnightly, or know of any projects that have documented doing stuff
> like this.
>
> Kind Regards
> Luke John
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-- 
Onno Benschop

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