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Old Dec 06, 2012, 12:40 PM
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Orlando, Fl
Joined Jan 2008
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orlbuzz,

I am in Orlando too. Where do you fly? I think you would still overload the cell, but Wayne can give you the right answer.

Jason
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Old Dec 06, 2012, 01:11 PM
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Harry D's Avatar
Canada, AB, Edmonton
Joined Oct 2004
1,259 Posts
No doubt Wayne will be along soon to provide the definitive answers to your questions, but I thought I would mention that I've been measuring the IR of the UM and other small cells for a while now.

I did Wayne's single-cell and low-current mods (Post #364) which work perfectly (as would be expected, coming from him ).

I made up a harness similar to what you describe, but for only two of the UM cells, so I could use the Kelvin measurement capability of the meter to eliminate lead resistance error. That worked fine, but I found that I got pretty much the same IR readings when measuring a single cell (using the auxiliary power source). In other words, the lead and connector resistance was negligible compared to the IR of these very small cells.

You do need the low current mod with small cells, perhaps to avoid any possible damage but more particularly to stay within the range of the meter. I use low range for anything under 500 mAh.

Wayne's meter has become my most-used RC tool, and has proved to be the best few hobby dollars I've ever spent. Thanks again, Wayne!
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Old Dec 06, 2012, 01:32 PM
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Rugby, UK
Joined Feb 2007
856 Posts
Quote:
Originally Posted by orlbuzz View Post
Having just purchased a Blade mCPx V2, I now have a need to check 1S lipos. My friends and I have ordered the 6 lead pigtail parallel charging lead. It occurred to me that I could cut the UM connectors with leads out of the pigtail and make up a harness to create a 2S, 3s, etc., battery by connecting them in series and (observing polarity), connect a Deans connector. I could then take a balance connector and insert it's leads in the appropriate places between each cell.

These cells will be 200 to 300 mAh each. Is my thinking correct that this would be the same, (using 200 mAh cells, for example), as a 3S, 600mAh battery?

I realize the UM connectors and the leads will add resistance not found in a assembled battery pack with soldered tabs, etc., but as a tool for comparison, would this work and not overload the individual cells with the pulse?
If I understand correctly you are making up a 3S battery from 3 individual 200 or 300mAh cells in which case it would be a 3S200 or 3S300 pack respectively

The meter is rated for 500 - 6000mAh packs and the minimum limit is based on the max IR the meter will read in "CELL" mode which is specified as 25 milliohms although in practice it will read up to about 30 milliohms.
If you try to measure a cell with an IR of over 30 milliohms then the system will saturate and you will get an optimistic reading.

The pulse will not cause any damage to a small cell because it is so short but the reading will not be reliable if it is >30milliohms.

Incidentally, the extra resistance of the connectors would not affect the readings.
The voltage sensing leads take no current so that they measure the voltage at the cell with no added voltage drop. The current pulse only passes through the power leads.

Wayne
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Old Dec 06, 2012, 07:42 PM
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Orlando, Fl.
Joined Sep 2006
55 Posts
Thanks Wayne, (and Jason and Harry),
I figured that out on the way home tonight. Darn, I thought for a while I had figured out a simple way to test the 1S cells I will be using. I'll have to take a close look at the mod.
Jason, I fly out by OIA and the Naval Exchange. There is a Jason that flies there too, is that you?
Gary
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Old Dec 06, 2012, 08:11 PM
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Orlando, Fl
Joined Jan 2008
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Quote:
Originally Posted by orlbuzz View Post
Thanks Wayne, (and Jason and Harry),
I figured that out on the way home tonight. Darn, I thought for a while I had figured out a simple way to test the 1S cells I will be using. I'll have to take a close look at the mod.
Jason, I fly out by OIA and the Naval Exchange. There is a Jason that flies there too, is that you?
Gary
That's me. Did you buy one of these meters? Mine should arrive next week.
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Old Dec 06, 2012, 09:02 PM
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Orlando, Fl.
Joined Sep 2006
55 Posts
Yes I did, about a week ago. I checked all my batteries and made a log.

I'll be asking for advice from you and JC on the uMX!! You two fly so well.!

I have company this week, so probably won't be out, but see you soon.

Gary
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Old Dec 09, 2012, 05:07 PM
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Joined Jun 2012
6 Posts
Hi,

I have made my own LiPo internal resistance tester. It is similar to Waynes with some differences. (I have not read about it before, just now, I searched for a forum to publish it.) Mine measures with 1ohm load, and measures only the separate cells with the 4 wire method. It can go up to 8 cells, but is tested only with 4. The specification is not so detailed, if anyone has a special need, it must be revised. It has some inacurancies, but I think it is quite useable. The big advantage is that it is free, the disadvantage is that you have to make your own, I just give every plan I have for it.

http://cseb.hu/lipo_rin

Critical components (except the microcontroller) can be ordered as a free sample from the manufacturer. the microcontroller can be disassembled from a faulty ESC. :-)

Regards,
Csaba
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Old Dec 11, 2012, 08:29 PM
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Brawley, CA. USA
Joined May 2000
476 Posts
Received my ESR meter but I have a (dumb?) question.

I measured total pack with the meter and received anywhere from 28 to36 ( 1800-2200 cells)( or is that OK, mix of new and old batteries) but I have a question about measuring indivual cells.

Do I plug the Deans conector into the battery and then for the indivual cell reading I plug the small conector into the balance plug, which is poliatry protected, while the Deans connector is still connected and take indivual cell readings by pushing the button each time I move down the line of the balance plug.

I tried it without the Deans conector being pluged in and received nothing on the display. Don't want to let the smoke out of my birthday present, my wife would be POed.

Thanks in advance if I don't reply later,

Bill
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Old Dec 11, 2012, 10:43 PM
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didge's Avatar
Adelaide, Australia
Joined Feb 2009
402 Posts
Yes that's correct Bill, you need the Deans connector plugged in as well. Did you lose the instructions?

Cheers
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Old Jan 28, 2013, 02:49 PM
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United Kingdom, England, Leyland
Joined Dec 2011
14 Posts
Meter arrived today and what a difference temperature makes in measurement.
I had one lipo in the house and room temp was about 17 deg c and the other batts where in the garage so they where about 10 deg c.
Initial readings where high with not one pack below 33 mili ohms and most above 48.
Then after leaving them for a few hours with the central heating on I did the readings again and only one pack was above 30 and the rest between 25 and 30.
Individual cell readings showed there to be a 3 to 3.5 milli ohm loss due to wiring and connector.
Many thanks to Wayne for his advice especially on the temperature issue
When I can stand 22 deg I will have another go to see if there's any further reduction.
The batts are 2200 mah 25c 3s overlander.
They are approx 20 months old with many cycles.
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Old Feb 10, 2013, 12:44 AM
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Birchleigh, South Africa
Joined Apr 2007
47 Posts
Puffed Lipo

Hi, I need some advise please. I have a Turnigy 2200mAh 3S 25-35C discharge rate that is quite puffed. Per the meter the IR is 7.64, therefore true C=19. Then I have Lipos that are not puffed, a Turnigy 2200mAh 3S 20-30C discharge rate, IR 9.64, therefore true C=17 and Zippy 2200mAh 3S 20C discharge rate, IR 13.64, therefore true C=14.

I've often read that puffed Lipos should be disposed of, but the puffed one certainly appears to be in a better condition than the other two, is it fine to continue using it?

Regards

Hennie
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Old Feb 10, 2013, 02:05 AM
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Rugby, UK
Joined Feb 2007
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Quote:
Originally Posted by hethjo View Post
Hi, I need some advise please. I have a Turnigy 2200mAh 3S 25-35C discharge rate that is quite puffed. Per the meter the IR is 7.64, therefore true C=19. Then I have Lipos that are not puffed, a Turnigy 2200mAh 3S 20-30C discharge rate, IR 9.64, therefore true C=17 and Zippy 2200mAh 3S 20C discharge rate, IR 13.64, therefore true C=14.

I've often read that puffed Lipos should be disposed of, but the puffed one certainly appears to be in a better condition than the other two, is it fine to continue using it?

Regards

Hennie
Hi Hennie,

I don't think there is a problem in continuing to use a puffed lipo.
Lots of people do so and report that they still continue to perform OK which would tie up with your IR readings.
The IR of all lipos increase generally with age so that you would expect the real
C rating to fall. When the pack is really at the end of its life, invariably one cell will rise dramatically in IR and that becomes very obvious in cell IR readings and in lack of performance.
I hope your meter has been useful.

Wayne
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Old Feb 10, 2013, 02:56 AM
Registered User
Birchleigh, South Africa
Joined Apr 2007
47 Posts
Thanks, Wayne, appreciate, confirms my thoughts.

Yes, the meter is very useful, so far found that Turnigy Lipos are not always up to advertised C-Rating, but not far off either and for me great value for money compared to much more expensive Lipos.

Regards

Hennie
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Old Feb 10, 2013, 08:10 AM
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United States, NJ, Clayton
Joined Aug 2010
1,580 Posts
Quote:
Originally Posted by PKNEC View Post
Meter arrived today and what a difference temperature makes in measurement.
I had one lipo in the house and room temp was about 17 deg c and the other batts where in the garage so they where about 10 deg c.
Initial readings where high with not one pack below 33 mili ohms and most above 48.
Then after leaving them for a few hours with the central heating on I did the readings again and only one pack was above 30 and the rest between 25 and 30.
Individual cell readings showed there to be a 3 to 3.5 milli ohm loss due to wiring and connector.
Many thanks to Wayne for his advice especially on the temperature issue
When I can stand 22 deg I will have another go to see if there's any further reduction.
The batts are 2200 mah 25c 3s overlander.
They are approx 20 months old with many cycles.
Quote:
Originally Posted by hethjo View Post
Hi, I need some advise please. I have a Turnigy 2200mAh 3S 25-35C discharge rate that is quite puffed. Per the meter the IR is 7.64, therefore true C=19. Then I have Lipos that are not puffed, a Turnigy 2200mAh 3S 20-30C discharge rate, IR 9.64, therefore true C=17 and Zippy 2200mAh 3S 20C discharge rate, IR 13.64, therefore true C=14.

I've often read that puffed Lipos should be disposed of, but the puffed one certainly appears to be in a better condition than the other two, is it fine to continue using it?

Regards

Hennie
Quote:
Originally Posted by Wayne Giles View Post
Hi Hennie,

I don't think there is a problem in continuing to use a puffed lipo.
Lots of people do so and report that they still continue to perform OK which would tie up with your IR readings.
The IR of all lipos increase generally with age so that you would expect the real
C rating to fall. When the pack is really at the end of its life, invariably one cell will rise dramatically in IR and that becomes very obvious in cell IR readings and in lack of performance.
I hope your meter has been useful.

Wayne
I have some hyperion 3s/4s 2200 45c batteries that have been squishy for close to two years, they have lost some capacity but they still put out decent power so i use them frome time to time with no ill effects.
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Old Feb 11, 2013, 07:10 AM
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United Kingdom, England, Ware
Joined Aug 2012
169 Posts
Hi Wayne

Working on the credit where credit principle and following arrival of your ESR meter please award yourself 10 out of 10 credit points .
Very simple and virtually fool proof bit of gear that falls into my category of ' best purchase for ages' list which I see has been refined with now a single push button compared to the original toggle switch .
A nice change from the many 'Snake Oil' claims made for electronic equipment often seen which dont live upto the claim
With the ability to arrive at the individual cell IR input into the performance tool http://www.jj604.com/LiPoTool/ or the stand alone Excel version here
http://www.rcgroups.com/forums/showt...1577989&page=1 it is no longer rocket science to determine if the many doubtful C rating claims can be accepted or rejected
The stand alone tool is particuraly usefull as loaded onto a suitable tablet can be used at the field to place your buddy into deep depression when the actual C rating of his favourite make of pack is made clear
In your attached instructions mention is made to ambient temperature having an effect of the IR readings does a reduction in the ambient have an inverse proportional effect of the true C rating ?
If a temperature drop affects the C rating does an increase in ambient have the opposite effect and at what stage does it level out ?
I pose the question as I see in your recent test of a Haiyin pack you were working on a ambient temp 25C which maybe a bit high for the UK average !
There is a similar thread -----http://www.rcgroups.com/forums/showthread.php?t=1767093----working on actual load testing to arrive at the actual .
Without starting world war 3 do both arrive at the same end result ?
Do realise that the meter is designed for use with Lipo packs but if used to check the IR of a NiCad pack can the resultant IR be used to arrive at the C rating of the pack ?

Cheers Jim
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