# internal resistance of a battery

Discussion in 'General Electronics Chat' started by Hurt_it_Circuit, Oct 6, 2012.

1. ### Hurt_it_Circuit Thread Starter Member

Oct 2, 2012
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Does the internal resistance increase as the voltage of the battery goes up? For example does a 1.5V battery have a lower internal resistance than a battery of 9V? Made from the same manafacture.

Apr 5, 2008
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Hello,

A 9 Volts battery consists of 6 AAA size batteries.
As the active area is smaller of those AAA cells, the internal resistance is higher.
The AA battery has a larger active area, so the internal resistance is lower.

Bertus

Boe and Hurt_it_Circuit like this.
3. ### Austin Clark Active Member

Dec 28, 2011
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The simple answer is no. Voltage and internal resistance aren't directly related.

Generally, the bigger the battery, the lower the ESR, because as was stated before, you have a bigger active area. Of course, different types of batteries have different ESR values as well.

A D cell has the same voltage as a AA, but is much bigger, has much lower ESR, and has a greater overall capacity.

4. ### Hurt_it_Circuit Thread Starter Member

Oct 2, 2012
53
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I am confused by a 9V battery has 6 AAA batteries and that the active area is smaller. I am new to circuits and I am taking my first class about them. What is active area mean? What does ESR mean?

When we conducted our lab it asked to measure the internal resistance of both batteries. When we set up our experiment we connected a 9V battery to a breadboard and a resistor (R1). We measured the current across and since the circuit is in series it does not change. We were having some difficulty with our multimeter and it began giving us odd measurements. We then plugged our values into Ohm's Law V(battery)=I*R1 + I*R(battery). We then solved for R(battery) and got like 29Ohm's for the 9V. We conducted same experiment for the 1.5V battery and got 8Ohm's. Did we set up the experiment properly?

Apr 5, 2008
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6. ### t06afre AAC Fanatic!

May 11, 2009
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This will also depend on the condition of the battery. The internal resistance will increase as the battery is discharged. So your result could be correct

7. ### Ron H AAC Fanatic!

Apr 14, 2005
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I think you meant AAAA, not AAA.

There are other ways of making a PP3 9V battery. See the Wikipedia article.

8. ### Ron H AAC Fanatic!

Apr 14, 2005
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In a 9V battery made up of 6 AAAA cells in series, the resistance will be 6 times that of a single AAAA.

9. ### bountyhunter Well-Known Member

Sep 7, 2009
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Some of the newer "9V" batteries I have taken apart use six short "stubby" cells instead of the long skinny ones.

10. ### peck68 Member

Nov 27, 2009
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All cells will have a resistance to them, also called Equivalent Series Resistance, these vary with different chemistries. NiMH batteries have a generally high resistance, generally able to supply only 1 or 2 amps under short circuit. While Lead Acid batteries can supply over 20 amps because of their low resistance!

If you have one cell with resistance R, and an identical cell in series, then hopefully you should know that resistances in series add up therefore the resistance now becomes 2R

Hope that helps a bit ?

I have two 3000F capacitors with a resistance so low they can supply over 100 amps!

Jul 18, 2012
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