9.7" screen on battery power? - Raspberry Pi Forums

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hei,

i'm trying make raspberry pi setup 9.7" screen (this one: lilliput fa1000- np/c/t - 9.7” hdmi touch- screen mon- itor - http://www.lilliputdirect.com/lilliput- ... h%3dfa1000), battery powered. otherwise setup has raspberry pi model b , slice of pi -wifi shield.
found battery: http://www.adafruit.com/products/962
i'm wondering how estimate how long setup run on battery power? give me hint or has experience battery powered touch screens?

i have noticed sneaky trick on adverts such battery packs. mah figure shown applies internal battery typically 3.7 volts (it varies cell discharges) not 5 volts. means if dc-dc converter (producing 5 volts output) 100% efficient mah figure 5v output 74% of figure shown. in practice converter not 100% efficient. maybe 90%. overall 2/3 of headline rating.

section 6 of monitor manual http://www.lilliputdirect.com/support/m ... fa1000.pdf says power consumption <10 watts, dc input voltage 7 24 , current consumption 560 ma. expect current consumption vary dramatically on 7-24 volt range 560 ma figure quoted without specifying voltage!

cannot drive monitor directly battery pack. need step converter, again less 100% efficiency.

assume 10 watts monitor , 5 rpi , wi-fi. thats 15 watts 3 amps @ 5 volts. 3 amps 2200 mah souce means 2.2/3 hours or 45 minutes.

, assumes 3300 mah true. tend on optimistic side , li cells start losing mah capability moment manufactured.


raspberrypi



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