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seasurfer

macrumors 6502a
Original poster
Dec 12, 2007
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Just wondering. If you have to charge you iPad Pro daily from 0% to 100%, what is your electricity bill going to be like for one year?
 
Just wondering. If you have to charge you iPad Pro daily from 0% to 100%, what is your electricity bill going to be like for one year?

A couple of dollars??

It isn't that much power used, the batteries aren't really that big so it is a pretty academic question. If you can afford it, you can afford to power it!
 
haven't tested, but i'd like to estimate the iPad pro takes pretty much same power as 12'' macbook. so the power draw is 10-15w. electricity price in the states ranges from 8-33 cent per kWh.

so lets take 20cents / kWh. that is using a 1000w device for an hour. in other words, a 10w device for 100 hours.

an iPad has an average battery life of 10 hours, so every charge takes 10w*10h=100wh=0.1kwh

in other words, 2 cents per charge, or, 0.08-0.33 cents per charge depending on your location in the states.
 
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Guessing - 12w maximum for 2 hours to fully charge. Won't be that much power needed, but time could be longer, I suppose.
(iPad doesn't need 10 hours to charge. Charging rate is much faster than normal use discharge.
So 24 W/Hours x 365 days = 8.76 kWhours x your local electric rate.
Average residential rate in the U.S. is 11.88¢ per kWh, so a rough guess for the U.S. would be just over a dollar.
- If you charged every day for two hours.
And, Every charge at full charging rate supported by the power adapter. I expect realtime charging rate (electrical usage) actually won't be that much current.
 
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Guessing - 12w maximum for 2 hours to fully charge. Won't be that much power needed, but time could be longer, I suppose.
(iPad doesn't need 10 hours to charge. Charging rate is much faster than normal use discharge.
So 24 W/Hours x 365 days = 8.76 kWhours x your local electric rate.
Average residential rate in the U.S. is 11.88¢ per kWh, so a rough guess for the U.S. would be just over a dollar.
- If you charged every day for two hours.
And, Every charge at full charging rate supported by the power adapter. I expect realtime charging rate (electrical usage) actually won't be that much current.

Wow. I think it takes about 3 hours or more the fully charge the iPad Pro? Not sure what is everyone's experience?

By your calculations, using the iPad Pro screen as light is cheaper than the light bulb?
 
Comparing the light from the iPad screen to an incandescent bulb? Would be cheaper with the iPad.
A minute or two of emergency lighting? Sure, why not?

I doubt the cost would be less if you compare with an LED or other alternative low power lighting. But, not exactly the job description of an iPad to give you effective lighting. Plus, compared to an iPad Pro, light bulbs will be cheaper to buy. (Hope you realize that :D )
 
Comparing the light from the iPad screen to an incandescent bulb? Would be cheaper with the iPad.
A minute or two of emergency lighting? Sure, why not?

I doubt the cost would be less if you compare with an LED or other alternative low power lighting. But, not exactly the job description of an iPad to give you effective lighting. Plus, compared to an iPad Pro, light bulbs will be cheaper to buy. (Hope you realize that :D )

Let's assume that the cost of the iPad is not a factor. Will it be cheaper to light a bulb a whole day or turning the iPad on with 100% brightness the whole day?
 
I use mine several hours per day (games, browsing, writing) and haven't had to charge it daily yet. Every other day I let it hit 100%, and that seems to be enough. Brightness is kept at...less than 50% as that's what's most comfortable to my eyes. I have noticed that from a very low battery percentage (less than 20%) it takes a LOT longer to fully charge than 3 hours. I suppose cost won't be even a remote factor for me charging-wise.
 
If you can afford it, you can afford to power it!
Maybe... Maybe Not

We read about lots of buyers who finance a iPhone or iPad they cannot afford.

They go to eBay to get a case for a few dollars, it's very revealing of how desperately many people want an Apple product.

Sad actually.
 
Regarding the comment above about a "case for a few dollars," I got an inexpensive case from Amazon for my iPP, not because I was trying to be cheap or save money, but because the Apple keyboard just isn't available yet (online or in stores). But I need a keyboard for it, so not having one wasn't an option at all. Was I supposed to walk around with it unprotected and be unproductive because I didn't want to wait 4 - 5 weeks for Apple's more expensive version to be available? Of course not. I'll get one later, but sometimes you have to make do with what you have.
 
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Someone can double-check my math but the iPP has a 38.5 Whr battery. Electricity generally goes for about .11 per kWhr. That means a single charge of the iPP is 1000/38.5=25.97 or ~1/26 of a kWhr, or .004 cents. Multiply that by 365 days a year, and you get ~14kWhr or $1.46/year to fully charge the iPP every day.

It's an interesting exercise, and cool to see how little energy these use!
 
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The calculations above would have to be revised for transmission loss in the adaptor, so maybe half the power would be lost.
 
Someone can double-check my math but the iPP has a 38.5 Whr battery. Electricity generally goes for about .11 per kWhr. That means a single charge of the iPP is 1000/38.5=25.97 or ~1/26 of a kWhr, or .004 cents. Multiply that by 365 days a year, and you get ~14kWhr or $1.46/year to fully charge the iPP every day.

It's an interesting exercise, and cool to see how little energy these use!
Charging a battery is never a 1:1 ratio. The conversion process of going from 120/220 volts to 5 volts results in heat (feel your charger, it gets quite warm when charging, that heat is lost energy.) Also, batteries will themselves will take more energy to recharge than their total capacity as the battery and its charging circuitry itself will also give off heat while charging.

In either case, even if you doubled the the total power to account for losses you're looking at 28 kilowatts per year if you fully charged and drained the iPP every day of the year. So assuming the high end of $0.20 per kilowatt hour, you're looking at a little more than $5 a year. In other words you got other much more power hungry devices like your refrigerator etc. To worry about!
 
There are losses to be sure, I just think they are probably too small to worry about. On our plug-in hybrid it's something on the order of ~10-15% loss. Not enough to bother with here. :)
 
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