# Homework Help: What happens when we connect 2 batteries + with +, - with -?

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1. Sep 9, 2015

### CasterlyRock

1. The problem statement, all variables and given/known data
Batteries are connected together with their + and - poles.

2. Relevant equations

3. The attempt at a solution
I quess that nothing happens because there is no change in potential difference.

Last edited: Sep 9, 2015
2. Sep 9, 2015

### HallsofIvy

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!)

3. Sep 9, 2015

### insightful

Sounds reasonable. Are you possibly also supposed to make an observation about the properties of the resulting battery pair?

4. Sep 9, 2015

### CasterlyRock

No, it only says that batteries are the same.

5. Sep 9, 2015

### insightful

I meant properties of the pair after connection compared to a single battery. Volts? Amps? Amp-hour capacity?

6. Sep 9, 2015

### CasterlyRock

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.

7. Sep 9, 2015

### insightful

Could you not say that you produced a "new" battery with the same volts, but twice the amp and amp-hour capacity?

8. Sep 9, 2015

### CasterlyRock

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?

9. Sep 9, 2015

### insightful

Why would it shine brighter with the same volts applied?

10. Sep 9, 2015

### CasterlyRock

P=I^2*R. You've said that amp is greater than before.

11. Sep 9, 2015

### insightful

No, I said the amp capacity is greater than before. How much greater?