Need formulas for the dis/charge of batteries

In summary: In order to account for that, you may want to keep track of the battery's temperature via a thermometer while discharging it.In summary, the aim of this homework is to investigate the discharge rate of batteries as a function of temperature. The data was taken from battery manufacturers' websites. The student is looking for formulas to help quantitatively explain the data. The temperature is not the battery temperature, but the room temperature. The student is also keeping track of the battery's temperature.
  • #1
Abhinavpsingh
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Been asked to write a four page introduction to an Extended Experimental Investigation. The topic is investigating the discharge rate of batteries as a function of temperature. Need some help

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  • #2
Hello Abhinavpsingh, ##\qquad## :welcome: ##\qquad## !

Here at PF we definitely value some initiative from thread posters, and for homework like this it's even mandatory that you post your own attempt -- or else we are not even allowed to assist. So give us an excuse to help you ! Write down a plan !
 
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  • #3
Well it all has to be related to the topic and be more on the physics side rather than the chemical processes.
I have started with What is a battery and gone into a basic history. I have the mentioned Volta and also the Baghdad battery. Next I have briefly highlighted different types of batteries, (primary and secondary). I plan on going into factors impacting battery performance. Then I will talk about the Ohm's law circle of formulae. I then plan to go more in depth into how batteries discharge and then the impact of temperature. What I need help with is linking more formulas to my investigation.
 
  • #4
Welcome to the PF @Abhinavpsingh :smile:

Have you looked through the datasheet curves at the battery manufacturers' websites? They won't be giving any formulas probably, but any formulas that you do find would have to match up with that empirical data. You may be able to find some research papers on battery chemistry that will help you find some quantitative formulas behind this empirical data.

http://www.ti.com/lit/an/snva533/snva533.pdf
https://batteryuniversity.com/learn/article/how_to_measure_state_of_charge
https://www.powerstream.com/AA-tests.htm
https://html.scirp.org/file/80512x5.png
246029
 
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  • #5
In addition to what @berkeman gave you, I would like to ask that you clarify your question.

Some batteries loose their charge just sitting on the shelf, and that can be influenced by temperature. That is a different question than how they discharge when supplying a load. That can also be influenced by temperature. Which of those two are you asking about?
 
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  • #6
Thank you @anorlunda
As this is being tested in a classroom setting, with a limited time frame, we are using a resistor and possibly a bulb to expedite the process. To power the circuit, we are using a 1.5V AA battery and measuring volts and amps via a multimeter
 
  • #7
Abhinavpsingh said:
Thank you @anorlunda
As this is being tested in a classroom setting, with a limited time frame, we are using a resistor and possibly a bulb to expedite the process. To power the circuit, we are using a 1.5V AA battery and measuring volts and amps via a multimeter
OK. In that case, the curves provided by @berkeman in #4 should provide your answer.

Be careful that the temperature is the battery temperature, not the room temperature. As you discharge the battery through a resistor, the battery may warm up.
 
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Related to Need formulas for the dis/charge of batteries

1. What are the different types of battery dis/charge formulas?

There are several types of battery dis/charge formulas, including the Peukert's Law formula, the Coulombic Efficiency formula, and the Capacity Fade formula. Each of these formulas is used to calculate different aspects of battery dis/charge, such as the rate of discharge or the efficiency of the battery.

2. How do I calculate the discharge rate of a battery?

The discharge rate of a battery can be calculated using the Peukert's Law formula, which takes into account the battery's capacity and the rate of discharge. The formula is: t = C / (I^k), where t is the discharge time, C is the battery's capacity, I is the discharge current, and k is a constant value that depends on the type of battery.

3. What is Coulombic Efficiency and how is it calculated?

Coulombic Efficiency is a measure of how efficiently a battery can store and release energy. It is calculated by dividing the amount of charge that can be extracted from a battery by the amount of charge that was put into it. The formula is: CE = Q_out / Q_in, where CE is the Coulombic Efficiency, Q_out is the output charge, and Q_in is the input charge.

4. How can I use the Capacity Fade formula to predict the lifespan of a battery?

The Capacity Fade formula is used to estimate the decrease in a battery's capacity over time. It takes into account factors such as the battery's chemistry, temperature, and number of charge/discharge cycles. The formula is: Cn = C0 * (1 - k*n), where Cn is the remaining capacity after n cycles, C0 is the initial capacity, and k is a constant value that depends on the battery's chemistry.

5. Can I use these formulas for all types of batteries?

While these formulas can be applied to many types of batteries, it is important to note that they may not be accurate for all battery chemistries and designs. It is always best to consult the manufacturer's specifications for more precise calculations.

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