leave their charger plugged in when not charging it The value for Wattage that we calculated earlier was based on Freys assumption that cell phone chargers spend their lifetimes plugged in- mostly in standby(vampire)mode. We now derive a new value for Wattage based on a different study by Roth and McKenney, which shows that the average cell phone only needs to spend a minimum 256 hours charging per year. In short, we make Wattage dependent strictly on its minimum battery requirements and assume that users only charge their phones enough to keep them charged for the entire day. Roth also suggests hat chargers require 3. 7 watts when charging tage Battery 1 Batterywattag Time Spent Charging x Wattage When Charging 256 Thus, Batterywattage x 3.7 watts=0.108 watts. The second term in Equation 4 is the same as in Equation 1. So Wattage =2.455 watts Recall that our previous value was attage=4.182 watts We now show the effects of this new, lower energy expenditure on the simulation. Also pictured is our previous analysis of the phone adoption timeline in the hypothetical nation 1200 The UMAP Journal 30(3)(2009). @Copyright 2009 by COMAP, Inc. All rights reserved• leave their charger plugged in when not charging it. The value for Cwattage that we calculated earlier was based on Frey’s assumption that cell phone chargers spend their lifetimes plugged in – mostly in standby (vampire) mode. We now derive a new value for Cwattage based on a different study by Roth and McKenney, which shows that the average cell phone only needs to spend a minimum 256 hours charging per year. In short, we make Cwattage dependent strictly on its minimum battery requirements and assume that users only charge their phones enough to keep them charged for the entire day. Roth also suggests that chargers require 3.7 watts when charging. Cwattage ′ = Batterywattage +  Cup front (joules) Clifetim e (seconds)  (4) Batterywattage = Time Spent Charging Lifetime ×WattageWhen Charging (5) Thus, Batterywattage = 256 (hours) 8760 (hours) × 3.7 watts = 0.108 watts. The second term in Equation 4 is the same as in Equation 1. So, • Cwattage ′ = 2.455 watts. Recall that our previous value was • Cwattage= 4.182 watts. We now show the effects of this new, lower energy expenditure on the simulation. Also pictured is our previous analysis of the phone adoption timeline in the hypothetical nation. 0 200 400 600 800 1000 1200 1400 1600 ’10 ’12 ’14 ’16 ’18 ’20 ’22 ’24 ’26 ’28 ’30 Power Consumption (Megawatts) Time Heavy Cell Phone Use Light Cell Phone Use Landline Only Figure 8. The UMAP Journal 30 (3) (2009). ©Copyright 2009 by COMAP, Inc. All rights reserved