The discussion focuses on calculating the time it takes for a car battery to lose its charge when the headlights are left on. The headlights consume a total power of 120 W, and the battery has a capacity of 95 A*h. By applying the formula P=IV, the current drawn by the headlights is determined to be 10 A. Consequently, the time until the battery is depleted is calculated by dividing the battery capacity (95 A*h) by the current (10 A), resulting in a total time of 9.5 hours before the battery fails.
PREREQUISITESAutomotive engineers, electrical technicians, and anyone involved in vehicle maintenance or battery management will benefit from this discussion.
Since power and voltage is given, we use P=IV to solve for the current I, correct ? And thanks!gneill said:Hi pandamonium, Welcome to Physics Forums.
Can you determine the amount of current drawn by the lights?
That's right. What value do you get for the current?pandamonium said:Since power and voltage is given, we use P=IV to solve for the current I, correct ? And thanks!
I got I=10.gneill said:That's right. What value do you get for the current?
Okay, now take a closer look at the units of the battery capacity. How long will you have to draw 10 A to equal that capacity?pandamonium said:I got I=10.
Oh, since 95 is the total charge that the battery can produce before failing, I can divide 95/10 to get the time before it fails, correct ?gneill said:Okay, now take a closer look at the units of the battery capacity. How long will you have to draw 10 A to equal that capacity?
Yes. You can check your logic by working with the units.pandamonium said:Oh, since 95 is the total charge that the battery can produce before failing, I can divide 95/10 to get the time before it fails, correct ?
Thanks for all the help ! I really appreciate it c:gneill said:Yes. You can check your logic by working with the units.