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Old Apr 14, 2011, 05:06 AM
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Originally Posted by ScotY View Post
Hi Wayne,

From your manual...

"It is possible to connect the meter in parallel with a working load (ESC + Motor) and monitor the ESR as the discharge proceeds. This will clearly demonstrate the self heating effect and consequent fall in ESR as the battery temperature rises."

Can you explain how you would do this? Would you press the button while the motor is running? Wouldn't this either put an excessive load on the pack and or confuse the meter? I'm very slow when it comes to electronics so please pardon the question.
Scot,
No problem as the pulse is so short; I have plotted the ESR of a lipo pack being discharged at constant current at max C rating and plotted the ESR of the pack by taking readings every 10 seconds. You don't need to remove the steady load, just connect the meter in parallel, as close to the pack as possible to avoid extra connector and lead losses.

Wayne
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Old May 09, 2011, 02:21 PM
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I recently took a lot of time to measure the IR of my batteries using a CellPro 10S. It took a lot of time, but it was worth it to know the IR. I then took each battery and recorded the max watts and of course there was a direct comparison of performance to IR. I then plotted the IR vs. Watts to determine what levels of IR are acceptable.

Using this meter would be a great benefit for pattern flyers to know which batteries are no longer performing.
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Old May 10, 2011, 03:00 AM
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Originally Posted by tclaridge View Post
subscribed.

I recently took a lot of time to measure the IR of my batteries using a CellPro 10S. It took a lot of time, but it was worth it to know the IR. I then took each battery and recorded the max watts and of course there was a direct comparison of performance to IR. I then plotted the IR vs. Watts to determine what levels of IR are acceptable.

Using this meter would be a great benefit for pattern flyers to know which batteries are no longer performing.
I agree totally; that's why I built the original unit - but I am prejudiced of course!

Wayne
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Old May 10, 2011, 09:08 AM
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Using this meter would be a great benefit for pattern flyers to know which batteries are no longer performing.
Not only pattern flyers - everyone who uses lipos in the size range it's designed for. A truly great piece of equipment. Thanks again, Wayne!
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Old May 14, 2011, 07:42 PM
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Wayne, sent paypal and email to verify you got it ok. Please PM me or email to know we are ok, since mine is backed by credit card-if there is a fee let me know and I will send the difference by whatever method is best.

Roger
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Old May 15, 2011, 04:19 AM
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Wayne, sent paypal and email to verify you got it ok. Please PM me or email to know we are ok, since mine is backed by credit card-if there is a fee let me know and I will send the difference by whatever method is best.

Roger
Yes, fine Roger. Unit was posted Friday, May 13th. Usually take about 6 days to US.
Have fun with it ; PM me if any problem or questions.
Wayne
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Old May 15, 2011, 02:10 PM
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I have an IR question on battery capacity size. I measured two big 6S5000mah batteries that are 45C Nanotech. They came to about 1.9mohm. But the little 3S2200mah 45C Nanotechs measure 4.7mohm. Is it just because a smaller cell capacity has more resistance?
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Old May 15, 2011, 02:20 PM
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Yes. With higher capacity typically comes lower internal resistance, especially if the packs are from the same manufacturer, have same 'C' rating, and similar usage history. Much in the same way that larger gauge wire has lower resistance than smaller gauge wire.
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Old May 15, 2011, 03:47 PM
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Originally Posted by tclaridge View Post
I have an IR question on battery capacity size. I measured two big 6S5000mah batteries that are 45C Nanotech. They came to about 1.9mohm. But the little 3S2200mah 45C Nanotechs measure 4.7mohm. Is it just because a smaller cell capacity has more resistance?
If one good 2500 25C cell has a 5 milli ohm internal resistance, then two in parallel would have a resistance of 2.5 milli ohms. The combination would be a 5000 mah cell. ESR is really a measure of how much the volts drop for a given pulse of current. It is a figure derived from measuring volts and current. Two identical batteries in parallel provide twice as much current as one and hence 'measure' half the internal resistance.

Chris
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Old May 15, 2011, 04:17 PM
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Quote:
Originally Posted by tclaridge View Post
I have an IR question on battery capacity size. I measured two big 6S5000mah batteries that are 45C Nanotech. They came to about 1.9mohm. But the little 3S2200mah 45C Nanotechs measure 4.7mohm. Is it just because a smaller cell capacity has more resistance?
Tony,

I believe that the relationship is approx. linear and suggested a "Figure Of Merit" to replace "C" ratings although Mark Forsyth originated the concept by his personal criteria for judging Lipos. There is a good discussion on it at :

http://www.rcgroups.com/forums/showthread.php?t=1392662

Wayne
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Old May 22, 2011, 06:32 AM
ancora imparo
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Melbourne, Australia
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Wayne, I think you posted or emailed me at one time the process for calibrating the ESR meter. Do you have that handy and could post again? It's just that anything with linear circuitry in it says "calibrate me" occasionally.

Would prefer to do on both 16A and 1.6A ranges.

Thanks, John
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Old May 22, 2011, 01:05 PM
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i think the 6 cell is to much to 3 9 it
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Old May 22, 2011, 01:06 PM
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if the compresser is facing up then the battery will run propely
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Old May 22, 2011, 03:51 PM
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Originally Posted by jj604 View Post
Wayne, I think you posted or emailed me at one time the process for calibrating the ESR meter. Do you have that handy and could post again? It's just that anything with linear circuitry in it says "calibrate me" occasionally.

Would prefer to do on both 16A and 1.6A ranges.

Thanks, John
Sorry John, I can't find a copy but will reconstruct it with a little circuit I use as a calibration device and post it as it may be interest to other users.
Too late tonight - give me 24 hours.

Wayne
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Old May 22, 2011, 04:56 PM
ancora imparo
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Thanks. Absolutely no rush. BTW did you ever get another batch of meters done with the proper PC board?

John
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Originally Posted by Wayne Giles View Post
Sorry John, I can't find a copy but will reconstruct it with a little circuit I use as a calibration device and post it as it may be interest to other users.
Too late tonight - give me 24 hours.

Wayne
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