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-   -   Internal resistance of different pack sizes (http://www.Wattflyer.com/forums/showthread.php?t=73149)

chuckinnc 02-06-2014 09:41 AM

Internal resistance of different pack sizes
 
My IR Turnigy meter came yesterday and as usuall with no instructions, so a few questions.

Should the batteries be fully charged when measurring IR ?

If I had a 2S and 3S pack of the same current, would the 3S give better
(lower milliohm) reading?

If I had 2S - 2000ma and a 2S - 4000ma would the higer
current pack give better reading?

This is if all packs were new and same brand.

CHELLIE 02-06-2014 10:00 AM

Hi, Maybe this info might be of some help.

http://www.rcgroups.com/forums/showthread.php?t=1787777


JetPlaneFlyer 02-06-2014 12:53 PM

Quote:

Originally Posted by chuckinnc (Post 939314)
Should the batteries be fully charged when measurring IR ?

IR does change quite a bit between discharged and fully charged. there is really no right or wrong way to measure it but try to always measure packs in the same charge state if you want to be able to compare results. Same thing goes for temeperature.
Quote:

Originally Posted by chuckinnc (Post 939314)
If I had a 2S and 3S pack of the same current, would the 3S give better
(lower milliohm) reading?

No, if you are measuring total pack resistance then the 3s would be higher because the resistance of all cells is added together. If you are measuring individual cell resistance then it will be the same for 3s as 2s (or any other number of cells)
Quote:

Originally Posted by chuckinnc (Post 939314)
If I had 2S - 2000ma and a 2S - 4000ma would the higer
current pack give better reading?

Yes, you would expect the 4000mAh battery to have around half the IR as the 2000mAh battery.. Note that the capacity in mAh (Milliamp-Hours) is a measure of charge capacity, not current as such.

kyleservicetech 02-07-2014 01:05 AM

Quote:

Originally Posted by chuckinnc (Post 939314)
My IR Turnigy meter came yesterday and as usuall with no instructions, so a few questions.

Should the batteries be fully charged when measurring IR ?

If I had a 2S and 3S pack of the same current, would the 3S give better
(lower milliohm) reading?

If I had 2S - 2000ma and a 2S - 4000ma would the higer
current pack give better reading?

This is if all packs were new and same brand.

FYI, some of those LiPo chargers such as the Cellpro line also include the capability of measuring individual cell resistances.


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