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Old 11-29-2004, 08:42 AM   #1
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Default Internal Resitance Numbers

Hey Guys,

I am aware of what are good numbers for the Average Voltage, but what are GOOD numbers and what are BAD numbers for the Internal Resistance of cells??
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Old 11-29-2004, 08:55 AM   #2
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The lower the IR numbers are the more punch the pack will have. This works in conjunction with the voltage. A pack with high voltage and low IR will result in a very powerful pack.
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Old 11-29-2004, 08:57 AM   #3
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Okay, I understand that but what is a good number and what is a bad number, roughly??
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Old 11-29-2004, 09:00 AM   #4
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Most matched packs are around mid 2 up to low 3. Anything lower would be better, anything higher would be bad.
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Old 11-29-2004, 09:01 AM   #5
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Oh okay, and this is measured in ohms. Cool. Thanks for that Nismo, that helps out a lot.
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Old 11-29-2004, 12:05 PM   #6
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If you look at individual cell values... specs for a batteries internal resistance from the manufacture of the cell (ie. sanyo) says between 1.2 and 3.7 milli ohms of resistance. The turbo matchers and other matching machines usually don't show the decimal point, so you may see 15 or 18 or 21 as the internal resistance value.
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Old 11-29-2004, 03:30 PM   #7
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Yeh, I had noticed that and presumed as much. Thanks for the confirmation though.
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Old 11-29-2004, 08:12 PM   #8
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A 15 or lower IR would be good.
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Old 11-30-2004, 07:29 AM   #9
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Actually, it's nothing to do with moving decimal points or anything of the sort. Actual and Relative IR are 2 different readings altogether.

Some matchers (myself included) use "Actual Internal Resistance", and readings should be, as someone else said, in the 2 to 3.5 range.

Some other matchers use "Relative Internal Resistance", which is a calculated number. (these are the IR numbers you see in the 10-20 range)

Both readings have their advantages and disadvantages. In both cases, the lower the better. Generally speaking, the higher volatage cells will have less IR than the lower voltage cells (of course there are always exceptions, but I am making a generalisation).

For example, on my current batch GP3300 cells, I'm seeing between 2.0 and 2.5 actual IR for my 1.175+ packs, and between 2.5 and 2.9 Actual IR for my 1.165+ packs - with 1.170+ packs somewhere in between.

Your mileage may vary.

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Old 12-01-2004, 06:29 AM   #10
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Thanks for clearing that up Ozoner. I am looking forward to seeing how Ben's Harris R/C cells go. They sound great, nice AIR and good voltage.
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