How Can I Calculate Battery Discharge Time Using a Formula?

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Discussion Overview

The discussion revolves around calculating battery discharge time using a formula in the context of an experiment involving a 9V battery connected to a 180 ohm resistor. Participants explore the relationship between battery discharge time and temperature, as well as the methodology for deriving a formula based on experimental data.

Discussion Character

  • Exploratory
  • Technical explanation
  • Experimental/applied

Main Points Raised

  • One participant suggests that the formula may be derived through experimentation, proposing the use of multiple batteries at different temperatures and measuring the time until the battery reaches a defined "dead" voltage.
  • Another participant mentions having conducted the experiment at three specific temperatures and a cutoff voltage, expressing difficulty in producing a fitting formula.
  • There is a question about the relationship between temperature and discharge time, with one participant asking if the relationship is linear or more complex.
  • Concerns are raised about the accuracy of temperature values reported in the experiment, suggesting that additional data points may be necessary for a reliable analysis.
  • Participants inquire about the "best fit" methods being learned, indicating a focus on data analysis techniques.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the nature of the relationship between temperature and battery discharge time, nor on the adequacy of the data collected. Multiple competing views regarding the methodology and analysis remain present.

Contextual Notes

Participants express uncertainty about the appropriate temperature values and the need for additional data points to improve the reliability of their findings. There is also ambiguity regarding the definition of "dead" battery voltage and its implications for the experiment.

abhipatil419
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Hi guys!
For a school experiment we are supposed to connect a 9v battery to a 180 ohm resistor and multimeter and calculate how long it take to die at different temperatures .
does anyone know how can i do this using a formula? I will need it in my report.

Thanks for the help! :)
 
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It sounds to me as though they want you to find the formula by performing the experiment.
How many temperature values will you be using? What voltage value are you using as the threshold for a "dead" battery?

I would think that you would use at least four 9V batteries, allow each to settle on one of four well-measured and well-distributed temperatures, check them periodically for "death", and measure and record the time.
The plot the results and fit a formula to them.

Using a Duracell and "death" at 0.1V at 50mA, expect you timings to be in the 5 to 8 hour range.
 
Hey Scott!
I have already conducted the experiment today with 3 diff. batteries at 3 temperatures : -22 C, 24 C and 35 C
the resistance was 180 ohm
the voltage cut off was 7 volts

I am having trouble producing a formula that fits
 
What were you times? Is there approximately a linear relationship or is it more complicated?
 
Here you go :)
 

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abhipatil419 said:
Here you go :)
Hmmm... 14 minutes between .Scott's post and your reply suggests that you didn't spend any time thinking about what @.Scott said. Let's try this again:
.Scott said:
Is there approximately a linear relationship or is it more complicated?
 
According to the text on your plot, the temperatures are -22, 25, 47. According to your post, they are -22, 24, 35.
If it's -22, 25, 47, a linear approximation is probably not good enough. You should collect more data - say at 2 and 36.
If it's -22, 24, 35, use the linear approximation. What kind of "best fit" methods are you learning about?
 
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