Question

How long (in hours) will it take to charge a Telsa S using a 250 V/70 A plug? Assume the battery has a capacity of 80 kWh and that the charging efficiency is 89%. Report your answer to the nearest hour.

Answer 1

Answer:

4 hours

Explanation:

Here we are given the battery capacity 80 kWh which is simply the power in watts ( or kilo-watts) multiplied by the time, and to obtain  P.Now, we need to remember that Power is given by the Voltage times the current I. We have all these values, so lets answer the question:

P = V I = 250 V x 70 A = 17,500 watts = 17500 watts x 1 kW/1000 watts = 17.5 kW

Assuming 89 % efficiency means we will need  17.5/0.89 kW :

17500/ 0.89 KW = 19.66 kW

Then

t in hours  = 80 kW h / 19.66 KW  = 4 hours (rounding to the nearest hour)