How to Calculate Phone Battery Usage?

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Homework Help Overview

The discussion revolves around calculating phone battery usage based on time spent using the phone and in standby mode. The subject area includes concepts of energy consumption and battery life management.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between time spent using the phone and in standby mode, questioning the assumption that battery draw is constant in both states. They discuss the implications of varying power consumption during usage versus standby.

Discussion Status

Participants are actively engaging in questioning the assumptions made about battery usage. Some have suggested that the energy consumption in standby mode is less than during active use, leading to further exploration of how this affects the calculations. There is no explicit consensus yet, but the discussion is productive in examining different perspectives.

Contextual Notes

Participants note the lack of specific information regarding the actual power consumption rates for both usage and standby modes, which is critical for accurate calculations.

moonman239
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I have a phone. Since it was last charged, I used it for 8 hours and it was on standby for 16. Now my battery's down to 50%. How much battery did I use when I used the phone?

I'm thinking it's as simple as x + 2x = 50%.
 
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moonman239 said:
I have a phone. Since it was last charged, I used it for 8 hours and it was on standby for 16. Now my battery's down to 50%. How much battery did I use when I used the phone?

I'm thinking it's as simple as x + 2x = 50%.
Maybe or maybe not. You're assuming that the battery draw is the same when the phone is in use versus when it's in standby mode. It's possible and maybe likely that the phone uses less power when it's in standby mode, since it might not need to use power to drive the screen. If so, your equation doesn't take this reduced current draw into account.
 
Mark44 said:
Maybe or maybe not. You're assuming that the battery draw is the same when the phone is in use versus when it's in standby mode. It's possible and maybe likely that the phone uses less power when it's in standby mode, since it might not need to use power to drive the screen. If so, your equation doesn't take this reduced current draw into account.

Yes, the screen shuts off in standby mode.
 
So the phone uses less energy in standby mode. Unfortunately, you do not know how much less. If you knew, for example, that in standby mode you phone uses fraction m of the amount of energy it uses when in use, you could argue that, since it was in standby twice as long as in use, the total energy uses is E+ 2mE= 0.5. That gives (1+ 2m)E=0.5 so the amount of energy used while in use would be E= (0.5)/(1+ 2m).
 

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