|
|
|
no, the calories you eat are kcals already.
|
so its 2500 kcal = 2 500 000 cal a day?
so it means calculation is off by 1000 multiple, so instead of 4 days, 1/250 of my daily calories is enough to charge a phone 
|
from your link:
Maximum output current: 500 mA
2000mAh / 500mA = 4h
which means you have to keep cranking it for 4 hours to completely charge you phone
but you'll never discharge it completely so 3 hours should be enough
|
United Kingdom20343 Posts
On November 14 2016 02:25 mantequilla wrote:so its 2500 kcal = 2 500 000 cal a day? so it means calculation is off by 1000 multiple, so instead of 4 days, 1/250 of my daily calories is enough to charge a phone
yeah
Burning >1KG of fat from charging a phone would be pretty insane :D
|
I was expecting a funny picture of AxCrank charging a phone. ^^
|
On November 14 2016 09:56 loginn wrote:
I was expecting a funny picture of AxCrank charging a phone. ^^
same. lol
|
On November 14 2016 09:56 loginn wrote:
I was expecting a funny picture of AxCrank charging a phone. ^^
Came here for this as well, disappointed
|
That is an amazing miscalculation.
|
On November 14 2016 02:25 mantequilla wrote:so its 2500 kcal = 2 500 000 cal a day? so it means calculation is off by 1000 multiple, so instead of 4 days, 1/250 of my daily calories is enough to charge a phone
Well... yes, except that between 60 and 75% of your daily calories are spent on merely keeping you alive and in rest. So the useable calories are only 25-40% of that.
Moreover, the efficiency is going to be lost at a further two points:
1. Converting chemical energy into kinetic energy (to turn the crank... note that I am already completely bypassing all inefficiencies of the metabolic process in your body)
2. Converting kinetic energy into electric energy (in your crank charger).
The latter is quite efficient, so lets say only 10% is lost to heat.
Unfortunately, the former is only 25% efficient according to http://physics.ucsd.edu/do-the-math/2011/11/mpg-of-a-human/
So that means, the total calories available for spending on charging your phone are actually only:
2500kcal * .25 *.9 = 562,5kcal
In other words, you will spend ~1/65 part of your daily calories. Still not bad, but not as good as 1/250 either (still better than 4 days worth 
However, returning to the first point, you also only have 25-40% of your daily intake available for freely spending, which is (assuming your resting state is highly efficient=
2500 * .4 = 1000 kcal, or, in kinetic energy, 250 kcal.
Converting that kinetic energy into electric energy with your hand crank:
250 * .9 = 225 kcal.
So, charging your mobile phone takes ~1/26th of the energy available to you (assuming you eat 2500 kcal worth of food) for spending on moving about.
|
|
|
|
|
|
EPT
