What happens when we connect 2 batteries + with +, - with -?

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SUMMARY

Connecting two batteries with their positive terminals together and negative terminals together results in no change in voltage or potential difference, provided both batteries have the same voltage. This configuration effectively places the batteries in parallel, maintaining the same voltage while doubling the amp-hour capacity. If connected in series (positive to negative), the batteries would drain quickly and could overheat the connecting wires. The discussion emphasizes the conceptual understanding of battery configurations and their implications on electrical properties.

PREREQUISITES
  • Basic understanding of electrical circuits
  • Knowledge of battery configurations (series vs. parallel)
  • Familiarity with voltage, current, and amp-hour capacity
  • Understanding of Ohm's Law and power calculations (P=I^2*R)
NEXT STEPS
  • Research the differences between series and parallel battery connections
  • Learn about battery capacity and how it affects circuit performance
  • Explore the implications of connecting batteries with different voltages
  • Investigate the thermal effects of high current in electrical circuits
USEFUL FOR

Students studying electrical engineering, hobbyists working with batteries, and anyone interested in understanding battery configurations and their effects on circuit performance.

CasterlyRock
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Homework Statement


Batteries are connected together with their + and - poles.

Homework Equations



The Attempt at a Solution


I quess that nothing happens because there is no change in potential difference.
 
Last edited:
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Exactly. Assuming of course that the two batteries do have the same voltage, nothing will happen. (If you connect them + to - and - to +, the two batteries will quickly drain and the wires connecting them may over heat. Not a good thing to do!)
 
CasterlyRock said:
I quess that nothing happens because there is no voltage difference.
Sounds reasonable. Are you possibly also supposed to make an observation about the properties of the resulting battery pair?
 
No, it only says that batteries are the same.
 
CasterlyRock said:
No, it only says that batteries are the same.
I meant properties of the pair after connection compared to a single battery. Volts? Amps? Amp-hour capacity?
 
insightful said:
I meant properties of the pair after connection compared to a single battery. Volts? Amps? Amp-hour capacity?
Really nothing except what I wrote. The question has a conceptual nature. I assumed that when connected, batteries are in parallel, that means the same potential as it was, so nothing changes.
 
Could you not say that you produced a "new" battery with the same volts, but twice the amp and amp-hour capacity?
 
insightful said:
Could you not say that you produced a "new" battery with the same volts, but twice the amp and amp-hour capacity?
I don't understand. Do you mean if I would apply a resistor to that new one battery (lets say a resistor is a lightbulb) it would shine brighter than one applied to the original battery?
 
CasterlyRock said:
I don't understand. Do you mean if I would apply a resistor to that new one battery (lets say a resistor is a lightbulb) it would shine brighter than one applied to the original battery?
Why would it shine brighter with the same volts applied?
 
  • #10
P=I^2*R. You've said that amp is greater than before.
 
  • #11
CasterlyRock said:
P=I^2*R. You've said that amp is greater than before.
No, I said the amp capacity is greater than before. How much greater?
 

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