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        Robbe IR Meter - was: Internal resistance

#1 Jimmy Andrews Jun 18, 2003 03:01 AM

[EFLT] Robbe IR Meter - was: Internal resistance
 
This message from Jimmy Andrews <jandrews@singnet.com.sg> brought to you by EFLIGHT!

Has anyone tried the battery IR (Internal Resistance) meter by Robbe?
http://data.robbe-online.net/robbe_pdf/P1122_1-8422.pdf

I wonder how useful and/or accurate it would be for e-fliers?

Rgds,
Jimmy



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#2 Red Scholefield Jun 18, 2003 03:01 AM

Re: [EFLT] Robbe IR Meter - was: Internal resistance
 
This message from "Red Scholefield" <redscho@bellsouth.net> brought to you by EFLIGHT!

The Robbe meter measures the AC Impedance, NOT the internal resistance.
There is a significant difference.

>From the web site mentioned:


Specification
Measurement range: 1 ... 30 cells, max. 50 V
Measurement freq.: approx. 1 kHz
Power supply: Internal: 2 x 9 V batteries
External: 9 V stabilised
mains PSU, or
8-cell NC battery,
e.g. transmitter battery

While there is some broad corrolation the AC Impeadance is quite meaningless
in the electric flight application.


Red S.
Red's R/C Battery Clinic
http://www.rcbatteryclinic.com
Check us out for "revolting" information.

----- Original Message -----
From: "Jimmy Andrews" <jandrews@singnet.com.sg>
To: <eflight@ezonemag.com>
Sent: Tuesday, June 17, 2003 9:41 AM
Subject: [EFLT] Robbe IR Meter - was: Internal resistance


> This message from Jimmy Andrews <jandrews@singnet.com.sg> brought to you

by EFLIGHT!
>
> Has anyone tried the battery IR (Internal Resistance) meter by Robbe?
> http://data.robbe-online.net/robbe_pdf/P1122_1-8422.pdf
>
> I wonder how useful and/or accurate it would be for e-fliers?
>
> Rgds,
> Jimmy




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#3 Rick Page Jun 18, 2003 03:01 AM

RE: [EFLT] Robbe IR Meter - was: Internal resistance
 
This message from Rick Page <rick-page@shaw.ca> brought to you by EFLIGHT!

>The Robbe meter measures the AC Impedance, NOT the internal resistance.

AC is the standard measurement though. Theoretically, the DC resistance is
easier since we just have to measure the voltage at 2 different loads.
http://www.buchmann.ca/Chap9-page2.asp
For M/E Calc, the AC Impedance is too low, but as has been pointed out, the
DC internal resistance is usually linearly related. Many of our battery
chargers calculate resistance to adjust the current during an automatic
charge (similar to the Cadex discreet method), but they don't report the
value.
In subsequent pages of the Buchmann chapter (above) he discusses the 2
measurements and the "memory effect" of crystal formation. This
crystallisation never occurs with flight batteries with our aggressive
charge and discharge cycles.

Rick.


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