Quote:
Originally Posted by sjfan
This is why the OP is a bit misleading; while the SD card does draw some power, it's tiny in the grand scheme of things. Virtually negligible. As I said above, it's like taking out your car's headrests to increase gas mileage: yeah, theoretically that would decrease the car's weight and make it more fuel efficient, but the actual impact is so small as to be irrelevant.
A micro SD card's sleep current is typically in the range of 0.2 mA drawn. If a Kindle with a typical 1420 mAH battery has 30 hours of continuous reading life, that's 47.333 mA of average draw; removing the SD card would decrease that to about 47.1 mA, saving you less than half a percent. Instead of 30 hours, you might get 30 hours and 7 minutes; it's not really going to be noticeable, and certainly isn't enough to impact how often you need to charge the battery.
On a non e-ink device like a tablet, the SD card will represent an even lower proportion of the power used—if you have a tablet with a 4000 mAH battery and 12 hour charge life, then it's normally drawing 416.67 mA. Knocking 0.2 off that is a saving of about 1/20 of 1%; instead of 12 hours, you might get 12 hours and 20 seconds of battery life from a charge.
All of these numbers are order-of-magnitude: maybe your SD card draws more like a 0.3 mA sleep current. But the basic story is the same: while there is a theoretical power draw there, there's not a big real-wold impact on reader battery lifespan (unlike with wifi or backlights, which can have a significant impact on battery life).
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..Which is why you'll find it at the bottom of the list.
However, if you have a device where you play games, watch video on, it makes sense to run it off of the internal drive. Not only for performance reasons, but also the power draw on data transfer on an SD card is much higher than it's idle draw. SD card slots on Ebook readers should mostly remain passive though...
Still, removing the card, is a power saving nonetheless.
Quote:
Originally Posted by ZodWallop
That, right there is what I was getting at.
If battery performance on your device is so poor you find yourself having to hack it to disable SD cards, touch screen and dictionaries, you likely should get a new device.
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From another perspective,
If you don't need the SD card slot, and can fit your library in internal memory, you could be saving battery by doing so.
If you're unaware of this, you may be using up more battery, paying for an SD card that can get lost, stolen with your device, or break down.
Internal SSDs last longer, and if your device is stolen, you might already have $15-25 available for a new one (if you didn't invest it in an SD card).