Internal resistance of D Cell Alkaline versus vs AA - NiMH ?

[iineijbaldj]

Wanted to compare the internal resistance of AA -NiMH
versus D-Alkaline. As much as I searched I found little.
This link showed someone did some research. Can anyone
verify how right it is ?

http://www.candlepowerforums.com/vb/archive/index.php/t-27611.html

To find the bit of info search for AAA when you go to the link.

You'll find a list of info which compares
the internal resistance but the columns don't line up so I'm not sure what I'm comparing.

I think that the AA - NiMH = 0.03ohms and the D-Alkaline = 0.173ohms.
Can someone verify that it's correct or close to right?

I don't need to know more but if someone does have some nice data that would look
good I'm sure more people besides me would like to see it. Feel free to post it in
response to my thread. Thank you.

PS: The reason I'm asking is that I have an electronic fly swatter that works a lot like a flash on a camera. You press a button and it charges up to a high voltage. You can hear the whine of the circuit. To me it sounds like the whine ramps up much faster using NiMH - AA's, in converter tubes, than using D-Alkaline. But I'd like to see the specs to verify what I think I see.

 

[SilverFox]

Hello Iineijbaldj,

Energizer has some data on this.

Here is their data on NiMh AA, and here is the data for an Alkaline D cell.

Tom

 

[eluminator]

The AA NiMH is about what I measure. I haven't tested an alkaline.

 

[wakibaki]

This is fairly easy to approximate experimentally for small cells.

From V=IR the internal resistance is the open circuit voltage divided by the short circuit current. Of course you can't measure these without affecting them, but a modern multimeter will give a close reading particularly with cells with a comparatively high internal resistance. Just measure the voltage and current without anything else in the loop.

A D cell NiMh might deliver 20C or 200A or more which will kill any regular meter so depending on the cell you might want to measure the voltage across a known shunt resistor and figure the current from that. Trouble is the internal resistance may be getting down near the same as the shunt since to get 20C the internal resistance must be 1.2/200= 0.006 ohms.

In that case you can measure the voltage across 2 different resistors and do a bit of algebra. You could get a couple big precision wirewound 0R01s and measure with one in circuit and then both. At 100A you're dissipating 100W in 0R01 so you need to do this pretty quick. Once you know the voltages then you've got the currents and I1(R1+RI)=I2(R2+RI). You know I1,I2,R1 & R2.

w

 

[iineijbaldj]

Hello Iineijbaldj,

Energizer has some data on this.

Here is their data on NiMh AA, and here is the data for an Alkaline D cell.

Tom

======
Thank you Tom. Here's that data. Nice to see if you convert an AA to D in a converter you might get better service from an AA
--
D Alkaline
Nominal Voltage: 1.5 volts
Nominal IR: 150 to 300 milliohms (fresh)*

AA NiMH
internal resistance of the cell varies with state of charge, as follows:
Cell 1/2 Discharged Cell Charged
40 millioh 30 milliohms

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