Calculating A-hrs: Understanding a Car Battery's Performance and Efficiency

  • Thread starter Thread starter nckaytee
  • Start date Start date
  • Tags Tags
    Calculation
Click For Summary
SUMMARY

The discussion focuses on calculating the duration a car battery rated at 70 A-hrs can last when operating at a current of 15A. The correct calculation shows that the battery can last 4.67 hours, or approximately 280 minutes, derived from the equation 70 A-hrs divided by 15 A. Participants clarify that converting A-hrs to coulombs is unnecessary for this calculation, emphasizing the simplicity of dividing amp-hours directly by amps to find hours.

PREREQUISITES
  • Understanding of amp-hours (A-hrs) and their significance in battery performance
  • Basic knowledge of electrical current and units (Amps)
  • Familiarity with unit conversion (hours to minutes)
  • Ability to perform simple algebraic calculations
NEXT STEPS
  • Research battery capacity and performance metrics in automotive applications
  • Learn about the relationship between current, voltage, and power in electrical systems
  • Explore advanced battery technologies and their efficiency ratings
  • Study the impact of load on battery life and performance in real-world scenarios
USEFUL FOR

Students studying electrical engineering, automotive technicians, and anyone interested in understanding battery performance and efficiency calculations.

nckaytee
Messages
39
Reaction score
0
My teacher posted a practice exam with no answers so I want to make sure I am doing my problems right.

A car battery is rated at 70 A-hrs. How many minutes can this battery last if it operates at a current of 15A?

I made an equation 70A/60min = Xmin/15A

So, X=17.5 min

Am I right?
 
Physics news on Phys.org


nckaytee said:
My teacher posted a practice exam with no answers so I want to make sure I am doing my problems right.

A car battery is rated at 70 A-hrs. How many minutes can this battery last if it operates at a current of 15A?

I made an equation 70A/60min = Xmin/15A

So, X=17.5 min

Am I right?

An amp is one coulombs per sec. That means that an Amp hour is 3600 coulombs.

70 amp hours is 252,000 coulombs.

15 amps is 15 coulombs per sec = 54,000 coulombs in an hour.
 


so 900 minutes?
 


nckaytee said:
so 900 minutes?

How did you get 900 minutes?

You have 252,000 coulombs to spend and you spend 54,000 an hour? How many hours is that again? Times how many minutes an hour?
 


Just divide 70 A-h by the 15 A, the A cross themselves out and your left with just the hours not necessary to switch to coulombs.
 

Similar threads

  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 6 ·
Replies
6
Views
7K
Replies
10
Views
5K
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 3 ·
Replies
3
Views
4K
Replies
54
Views
12K
Replies
0
Views
2K