MobileRead Forums - View Single Post - Color jetBook Color Hand-On Review

ProDigit · 02-15-2012, 04:55 PM

External SD card uses very little energy over internal (only because both internal and external devices are powered).
So to extend battery life you'd have to rely on the internal memory. Though I doubt it's going to make a lot of difference.

I read somewhere the power consumption of a SD card is in the ranges of 250mW in use, 60mW idle.
Let's say that it just runs idle all the time, you'd basically be using up 1W every 4 hours just having the device plugged in.

I suspect the jetbook Color has 2x 3.6V @1000mAh batteries installed, in other words, you'd be losing about 3,5% battery life per hour just having a SD card plugged in; peaking at 15% battery use at constant read/write use.

Rough estimates...

Internal memory might use more battery than SD, but is faster, and is always on.
So even if it's idle, you'd still be using power for the SD card, plus the internal memory.

02-15-2012, 04:55 PM	#257
ProDigit Karmaniac Posts: 2,553 Karma: 11499146 Join Date: Oct 2008 Location: Miami FL Device: PRS-505, Jetbook, + Mini, +Color, Astak Ez Reader Pro, PPW1, Aura H2O	External SD card uses very little energy over internal (only because both internal and external devices are powered). So to extend battery life you'd have to rely on the internal memory. Though I doubt it's going to make a lot of difference. I read somewhere the power consumption of a SD card is in the ranges of 250mW in use, 60mW idle. Let's say that it just runs idle all the time, you'd basically be using up 1W every 4 hours just having the device plugged in. I suspect the jetbook Color has 2x 3.6V @1000mAh batteries installed, in other words, you'd be losing about 3,5% battery life per hour just having a SD card plugged in; peaking at 15% battery use at constant read/write use. Rough estimates... Internal memory might use more battery than SD, but is faster, and is always on. So even if it's idle, you'd still be using power for the SD card, plus the internal memory. Last edited by ProDigit; 02-15-2012 at 05:03 PM.