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A comment on SpareOne: Emergency mobile phone powered by AA batteries. Parent comment

Re:SpareOne: Emergency mobile phone powered by AA batteries by nickpsecurity on Sunday May 15, 2016 @12:25PM (#11701499)
I didn't know those exist. What's the comparison like vs this phone? As in, one AA battery provides 10 hours worth of talk time per their claims. How many times or how much charge do you get from the USB version?
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Re:SpareOne: Emergency mobile phone powered by AA batteries by digi_owl on Monday May 16, 2016 @07:03AM (#11705519)
Lets try some math. Most mobile batteries today is 3.7V.

An AA is 1.5V (rechargeable AAs are 1.2V).

Once that is established, it all comes down to the mAh.

Most AAs sold these days are listed as 2500mAh, multiply that with 1.5V and you get 3.750 Watts.

Note that this is very close to what you get from a 1000mAh li-ion battery found in many phones (3.7*1000=3700).

Now with a external li-ion emergency battery you will get conversion losses, as it has to go up to 5V for the USB and then back down again at the other end.

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Re:SpareOne: Emergency mobile phone powered by AA batteries by nickpsecurity on Monday May 16, 2016 @11:33PM (#11711210)
Very interesting and EE-like approach. :)
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Re:SpareOne: Emergency mobile phone powered by AA batteries by icebraining on Sunday May 15, 2016 @01:19PM (#11701753)
How many times or how much charge do you get from the USB version?

Considering that different phones consume different amounts of energy, and that different AA batteries have different capacities, that's hard to say.

If you carry a Wiko Lubi like me, you can probably talk more than 10h with a single battery. If you carry an energy-hungry smartphone, you'll probably get an order of magnitude less.

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Re:SpareOne: Emergency mobile phone powered by AA batteries by nickpsecurity on Sunday May 15, 2016 @02:09PM (#11701992)
Gotcha. Makes sense.
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Re:SpareOne: Emergency mobile phone powered by AA batteries by int_19h on Sunday May 15, 2016 @05:53PM (#11702943)
It all depends on the phone, obviously. With a Nexus 5 and 4 Energizer Ultimate Lithium AA batteries, I could recharge it to 100%, and then once again to 50%.
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