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Old Jun 04, 2014, 09:10 PM
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Thanks for the input gentlemen. The reason I made that statement was because I measured several of my other packs from 3s to 5s , 20c , 25c 30-70c and only the packs that are shot show readings this high. I also received some fresh 3s 5000 25c around February and did an IR test which were 3s and 4s. I thought that was high for a new pack until I did 2 cycles and now shows 1s and 2s. OK fair enough, but IR in the 20s. No something is wrong. I have never bought TP or the more expensive packs. I use Sky Lipos, Zippys, Vortex, Turnigy Nanos and GenAce. I never saw readings like this and btw Rhinos suppose to be as good as GenAces so what gives. To date SkyLipos surprise me the most, they are the cheapest and last the longest.
I go to a field where many of the pattern guys use the Skys, and I see battery packs full of cycle marks made by the pilots. Some still use packs that are 2 years old.
And almost forgot room temp was around 75. The packs looks new , its just my question is why would a new pack have readings this high. 4s or even 5s or 6 but in the 20s????
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Old Jun 04, 2014, 09:29 PM
ancora imparo
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Joined Jul 2005
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Just double checking that you understand Wayne's comment

"Also the IR of a cell is inversely proportional to the cell capacity"

Small 1350mAh packs have much higher IR than your 5000mAh packs. Around 4x as high for the same quality pack.

Your Rhinos do look high to me but have you checked the IR of your other 1350mAh packs with the same charger? I would regard an IR of 9mOhm/cell for a 1350mAh pack to be excellent. 4-6mOhm is very unlikely.

Rhinos have a good reputation but it is a budget Zippy pack from HobbyKing. Up to 15mOhm/cell is probably expected IMO.

John

John

Quote:
Originally Posted by 91-ZULU View Post
Thanks for the input gentlemen. The reason I made that statement was because I measured several of my other packs from 3s to 5s , 20c , 25c 30-70c and only the packs that are shot show readings this high. I also received some fresh 3s 5000 25c around February and did an IR test which were 3s and 4s. I thought that was high for a new pack until I did 2 cycles and now shows 1s and 2s. OK fair enough, but IR in the 20s. No something is wrong. I have never bought TP or the more expensive packs. I use Sky Lipos, Zippys, Vortex, Turnigy Nanos and GenAce. I never saw readings like this and btw Rhinos suppose to be as good as GenAces so what gives. To date SkyLipos surprise me the most, they are the cheapest and last the longest.
I go to a field where many of the pattern guys use the Skys, and I see battery packs full of cycle marks made by the pilots. Some still use packs that are 2 years old.
And almost forgot room temp was around 75. The packs looks new , its just my question is why would a new pack have readings this high. 4s or even 5s or 6 but in the 20s????
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Old Jun 04, 2014, 10:17 PM
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My 2 Skys that are about 1.5 year old and are puff a bit.
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Old Jun 16, 2014, 10:50 PM
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My US supplier is out of stock. Any ideas where I can get a meter? My old one stopped working.
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Old Jun 17, 2014, 01:47 AM
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Originally Posted by tclaridge View Post
My US supplier is out of stock. Any ideas where I can get a meter? My old one stopped working.
I will repair it free provided it has not been misused, send it back to me.
I have only had 2 failures in total till now.

Send me a PM with symptoms and e mail address as I may be able to diagnose the problem by mail. If not I will send a return address.

Wayne
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Old Jun 19, 2014, 01:59 PM
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I have a recent version of the Giles ESR device and I would like to start using it.

I have a batch of Hobbyking 3S 2.2 amp NanoTech batteries of varying ages and I know some of them are weak. Is it realistic to establish a ESR/IR reading, or range, that would establish valid criteria for discarding any of these batteries when their pack ESR/IR reading exceeds a certain number?

Thank you.
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Old Jun 19, 2014, 02:03 PM
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Gee, without the manufacturing specs how can you decide?
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Old Jun 19, 2014, 02:11 PM
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Gee, without the manufacturing specs how can you decide?
I have some new never used HK NT 3S 2.2amp packs that could possibly be used to establish a baseline ESR/IR reading?
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Old Jun 19, 2014, 02:22 PM
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Originally Posted by itsme2 View Post
I have a recent version of the Giles ESR device and I would like to start using it.

I have a batch of Hobbyking 3S 2.2 amp NanoTech batteries of varying ages and I know some of them are weak. Is it realistic to establish a ESR/IR reading, or range, that would establish valid criteria for discarding any of these batteries when their pack ESR/IR reading exceeds a certain number?

Thank you.
Use the meter to measure each cell on the packs, ensuring that they are all at about 22*C, and put the highest value cell in each pack into the Lipotool.
This will give you a max safe continuous current value that you can take from that lipo pack.
The Lipotool is here : http://www.jj604.com/LiPoTool/

The results also give you a FOM. (Figure of Merit) which enables you to compare each lipo pack with any other. The weak ones will have a lower FOM. A good lipo pack should have an FOM of 1 or near to it.

You will probably also find that the poorest packs show a much larger divergence of cell IR values. When a pack is showing signs of dying invariably one cell will go much higher IR which becomes obvious when you measure all the cell IRs.

Wayne
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Old Jun 19, 2014, 05:17 PM
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Originally Posted by Wayne Giles View Post

You will probably also find that the poorest packs show a much larger divergence of cell IR values. When a pack is showing signs of dying invariably one cell will go much higher IR which becomes obvious when you measure all the cell IRs.

Wayne
What would be a typical one cell "much higher IR" reading on a 3S lipo to warrant condemning a pack?

Thank you.
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Old Jun 19, 2014, 07:30 PM
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What would be a typical one cell "much higher IR" reading on a 3S lipo to warrant condemning a pack?
When the cell is at risk of being damaged due to internal heat generation. e.g. - Do not exceed the continuous current draw as recommended by the LipoTool and you'll be fine. If you're getting close to this number, use the pack in a less demanding application or retire it altogether.

Mark
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Old Jun 20, 2014, 01:21 AM
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Thanks Mark - perfect answer.

Wayne
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Old Jun 20, 2014, 07:40 AM
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Originally Posted by mrforsyth View Post
When the cell is at risk of being damaged due to internal heat generation. e.g. - Do not exceed the continuous current draw as recommended by the LipoTool and you'll be fine. If you're getting close to this number, use the pack in a less demanding application or retire it altogether.

Mark
Does the pack C rating factor into the equation in any way?
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Old Jun 20, 2014, 09:35 AM
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Does the pack C rating factor into the equation in any way?
Not at all.

It's widely recognized that the 'C' rating is very generous and not very accurate more often than not. This is precisely why devices such as Wayne's ESR Meter are so very handy. They provide an empirical indication of actual performance rather than being a number on a fancy label stuck to the side of a pack.

With the ESR Meter and the LiPoTool, you now have a very solid and proven method of determining the performance capabilities of your packs and can effectively track and manage your lipoly collection.

For more information on the LiPoTool, read here: http://www.rcgroups.com/forums/showthread.php?t=1577989

Also, the following thread contains a downloadable spreadsheet that contains all of the calculations in the LiPoTool and allows you to have all of your performance data in one place: http://www.rcgroups.com/forums/showt...1#post20484169

Mark
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Old Jul 03, 2014, 04:07 PM
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Joined Jul 2012
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I've got some measurements with the Wayne Giles meter and with my PL6, and I'm not entirely sure what they mean.

I bought 2 4S 2600 30C lipos almost 2 years ago, and another 2 about 1 year ago, but I didn't actually start using any of them until about a month ago. During that time they were stored in a metal box on my basement floor, which is somewhere in the low 60s or upper 50s in the winter, and somewhere in the low 70s in the summer. They were at approximately storage voltage.

When I measure them with the ESR meter I get around 9 milli ohms per cell - although one battery has a high cell of 10.32 and a low of 7.68, measured at 72 degrees F (the temp of my metal box on the basement floor recently). The lipo tool (http://jj604.com/LiPoTool/) tells me that they're good for right around 40 amps.
When I use the PL6 to measure the IR from the same storage charge rate at the same temperature, it comes up with significantly different numbers. Not only that, but the pattern of the numbers is different. Some numbers are close, some wildly different. The two measurement methods don't even agree on which cell has the highest IR, or the lowest IR. For example:
lipo 21, ESR meter: 9.12, 8.88, 8.44, 8.80
lipo 21, PL6: 8.3, 6.8, 3.6, 10.9
Another battery shows a similar disagreement about which is the low and high cells, but all the numbers are lower with the PL6.

With the ESR meter, I have an adapter cable to go from the deans on the meter to the powerpoles on the batteries. With the PL6 I have a charge cable for powerpoles, and a 4S balance cable plugged into the adapter board which is in turn plugged into the PL6. It occurs to me as I type this that I could eliminate the balance cable and plug the balance lead on the battery straight into the adapter board - basically I just plugged the battery into the same harness I use for parallel charging, but this time with only the single battery.

I'm using these in two planes, one which measures a peak of 900 watts or so (forgot to write down the max amps), the other a peak of around 715 watts, 47 amps. These are new planes, I've never flown them with any other lipos, so I don't have anything to compare these batteries to. Neither plane is lacking in power at all, I can do full throttle vertical uplines that cruise up fast enough to bring a smile to your face. Flight pack voltage telemetry shows the min voltage never drops to a point I would think was bad - I think 3.5v per cell is the lowest I remember seeing in flight. At rest voltage after a flight is so far always at worst slightly below storage voltage (I've been conservative with flight times). The lipos come down mildly warm, around 105 F if I remember right. So it seems as if the batteries can dish out what the planes are asking for, even though that would appear to be well above what the simple lipo performance tool says they can provide given the IR measurements.

Things I'm wondering, in no particular order:

- Why the major difference in measurement between the ESR meter and the PL6, specifically the disagreement on low and high cells? Could it be because of the extra balance cable on the PL6, scuz on connectors, something like that?

- I assume the ESR meter is more accurate. Since the 4 wire measurement is being used, I don't think the adapter cable for the powerpoles should affect the measurement?

- Although the performance I'm getting out of the batteries in the airplanes more than meets my expectations, perhaps I'm not expecting enough? If I bought a couple new ones would I get a surprisingly higher power level out?

- Would I be happier if I was blissfully ignorant of the whole concept of IR?
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