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05-09-2011 07:51 PM  7 years agoPost 1
AnneThe Man

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Ireland

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I recently purchased a couple of 35C 6S 5000 packs for my ENV which is still being built.
In preparation I discharged and charged a couple of times at 0.5C, discharging to 3.7V. The IR goes up every cycle by around 0.2.
On receipt the IR was between 2.4 and 3.4, which I guess is OK, but after 3 cycles they have increased to between 3.4 and 4.0.
Do these figures mean anything?
I use a cellpro 10.

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05-09-2011 09:17 PM  7 years agoPost 2
Gregor99

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Western Wa

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On the Cellpro10s for accurate IR measurement you need to use a manual charge rate of 1c (no auto mode 1c). IR can be impacted by a number of things including pack tempature, and state of charge. Generally speaking an increase in IR over time is expected. But the percentage of increases you are seeing are likely within the margin of error for IR measurement. If the trend continues with each successive charge, then that would indicate a problem with the packs. I'd start by trying standardize your measurement process. 1c charging, start from close to the same state of charge and pack tempature.

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05-10-2011 03:39 PM  7 years agoPost 3
AnneThe Man

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Ireland

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Thanks. Temperature has been consistant as have charge and discharge rates at 0.26A or just over 0.5C, with several hours resting between charge and discharge. Discharge has been using a CBAII so that too is consistant with discharge stopping at 3.7V.
I hope you're right and these are just imprecise measurements.
Only time will tell when I start flying them.

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05-11-2011 09:53 PM  7 years agoPost 4
JOLT

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Baltimore, MD

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I wanted to chime in on this because I am really discovering the importance of IR in the quality of a battery pack. I charge Turnigy 3000mah 6S 30C lipos at 1C.

I have always subscribed to the thought that Turnigy is a bargain and the way to go. I am starting to shift that philosophy as I am realizing the IR on a Turnigy pack is terrible and causes a lot of problems over time. One being, inconsistent balancing peaks causing problems receiving charge that higher qulaity lipos do not have showing a much lower IR value.

Just a predicition, but I think more and more people will be converting their Turnigy stash of MANY Lipos to higher quality chargers with higher quality batteries as more knowledge of IR and other important factors become known to everyone.

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05-11-2011 11:03 PM  7 years agoPost 5
helicraze

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Victoria - Australia

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Yep, for me the cost of the turnigy (take into account the failures) the extra weight (talking upto 200-300 grams on 12S) and the extra size of HK packs along with IR getting worse (not better) and balancing taking longer etc and no warranty i opt for TP packs, 2 6S packs only a little over $400 smackers and 65C rating!

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05-12-2011 01:55 AM  7 years agoPost 6
w12martin

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Chengdu, Sichuan, China

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Sorry to hear your bad experience with turnigy batteries.
In my case, I have over 100 cycles on my turnigy 3S 40C and the IR is not that good, but... I don't care much about that after 100 cycles on a 20 dollars battery.
On my 700E, I use Turnigy Nano-Tech 4000mha 25/50 and the IR is pretty good and getting lower after 35 cycles...

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05-12-2011 03:41 AM  7 years agoPost 7
Twrecks600

rrKey Veteran

Round Rock, Texas

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I run 2 X 6s, 5300 mAh, 30c (12s setup) Spyder packs and I charge at 3c EVERY charge and my IR is NEVER above .8m. Any battery that gets above 2.0 is used strictly for hovering packs due to the possibility of heat buildup.

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05-12-2011 03:53 AM  7 years agoPost 8
Ace Dude

rrProfessor

USA

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Just a predicition, but I think more and more people will be converting their Turnigy stash of MANY Lipos to higher quality chargers with higher quality batteries as more knowledge of IR and other important factors become known to everyone.
I highly doubt it. I've always purchased high quality batteries (Hyperion, TP, Neu, FlightPower, etc.), but I doubt many will switch. I understand the importance of IR, but many purchase Turning for one reason.

  

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05-12-2011 03:36 PM  7 years agoPost 9
Gregor99

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Western Wa

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Temperature has been consistant as have charge and discharge rates at 0.26A or just over 0.5C,
On the Cellpro 10s I would use a 1C charge rate for checking the IR. While I do like your testing methodolgy, I suspect you would see slightly lower IR figures if you were to increase your discharge rate and lower your "resting" time.
but many purchase Turning for one reason
Agreed. Then they come the forums and complain about packs that arrvied with low, or dead cells, premature puffing, cold solder joints, long delays in shipping, incorrect orders and rant about service.

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05-12-2011 04:05 PM  7 years agoPost 10
AnneThe Man

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Ireland

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My packs were $115 each, so not particularly cheap. Is it possible for the IR to go down?

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05-12-2011 04:40 PM  7 years agoPost 11
dxflyer

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Bay area, California

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Yes I have noticed some new packs IR go down after some cycles.

Logo 600 12S vbar, Logo 500 vbar
Protos FBL vbar

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05-12-2011 05:18 PM  7 years agoPost 12
rexxigpilot

rrProfessor

Florida

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The photos above show the IR per cell of a Flightmax 4Ah, 6S battery that has just under 100 flights/cycles. I cycled the pack from full to storage charge then back to full on my PL8 charger, then photographed the IR readings. This pack started out with cell IR's from 1.5 to 2.0. If you didn't know, the Flightmax line is the bottom tier of the batteries from HK/hextronix. Turnigy is the top and the Rhino is the mid grade line. So, I can say with verifiable proof that there is no difference in quality between a TP pack and those from HK. If the placebo effect works for you by buying something more expensive, go for it.

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05-12-2011 05:31 PM  7 years agoPost 13
Ace Dude

rrProfessor

USA

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So, I can say with verifiable proof that there is no difference in quality between a TP pack and those from HK.
So you're saying that IR is the only factor that determines a high quality pack?

  

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05-12-2011 06:19 PM  7 years agoPost 14
rexxigpilot

rrProfessor

Florida

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You tell me what else matters Ace Dude? IR is the whole point of this thread! Lipo cells are all made in the same few factories. The difference between say a 40C Turnigy pack and 40C Flightmax is not related to performance. For instance, the balance lead wires on a Turnigy have silicone insulation whereas the Flightmax is PVC (which is cheaper but not very flexible). The wrapping of the cells on a Turnigy includes a protective plastic film/tape on the butt end. The Flightmax has none. I could go on an on, but I don't want to sound like a Stephen Bishop song. Buy what you want, It's your money!

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05-12-2011 09:56 PM  7 years agoPost 15
Ace Dude

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USA

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You tell me what else matters Ace Dude?
To me, cycle life and ability to hold voltage under load are also important factors in assessing overall quality.
IR is the whole point of this thread!
That doesn't mean it's the only point.
Lipo cells are all made in the same few factories.
Can you provide us a list of all the factories? Should be easy since it's only a few, right?
The difference between say a 40C Turnigy pack and 40C Flightmax is not related to performance. For instance, the balance lead wires on a Turnigy have silicone insulation whereas the Flightmax is PVC (which is cheaper but not very flexible). The wrapping of the cells on a Turnigy includes a protective plastic film/tape on the butt end. The Flightmax has none.
Cool, so if the PVC melts at 200F and the silicone melts at 500F that's not performance related. Of course, if this thread is about IR why are you discussing the type of wire insulation used?

  

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05-12-2011 11:14 PM  7 years agoPost 16
Gregor99

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Western Wa

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I've really come to take IR values with very big grain of salt. Using them to compare packs can be pointless and really only valid in the realms of marketing. The same groups that determine C ratings. I've had packs with puffed cells, not holding voltage showing good IR values. I've had good cells that work fine showing higher IR values. Sure, there are trends over time. But the mechanism used to measure IR is not precise and varies from charger to charger. IMO the only real numbers to be concerned about is how the packs hold voltage under load. Far more telling than the IR values so many misplace thier faith in.

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05-13-2011 12:07 AM  7 years agoPost 17
rexxigpilot

rrProfessor

Florida

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To me, cycle life and ability to hold voltage under load are also important factors in assessing overall quality.
I hope you are aware that holding voltage under load is a function of the IR. The lower the IR the less voltage drop under load - Ohm's law. The IR is also mostly what determines the C rating of one LiPo versus another.

Regarding pack life, if you read my post carefully you would have noticed the almost 100 flights/cycles part. My experience with even the cheapest of the batteries from HK, Flightmax, indicates they provide reasonably long life if cared for properly. A change in IR from 1.5 to 2.5 after almost 100 cycles is excellent performance. This indicates that the packs are now capable of operating like 24C packs still.
Cool, so if the PVC melts at 200F and the silicone melts at 500F that's not performance related. Of course, if this thread is about IR why are you discussing the type of wire insulation used?
Actually the common max. operating temps for PVC and Silicone wire insulation are 221°(105°C) and 392F (200°C), respectively. But both these values are far above what your battery will see in normal use. If your battery gets to 221°F it is toast anyway. My point was that there are ways to save money on a battery construction that won't affect the performace. Most people got this point!

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05-13-2011 01:40 AM  7 years agoPost 18
Gregor99

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Western Wa

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I hope you are aware that holding voltage under load is a function of the IR.
Completely agree. But since IR values as measured and reported by our hobby grade equipment are not always reliable indicators of pack performance, one can only assume that the measurement equipment or methods are at best questionable. Whereas, voltage under load is far easier to measure and is a much more reliable indicator of pack performance.
The IR is also mostly what determines the C rating of one LiPo versus another
In theory. But in practice, it ends up being more marketing spin. For example I have a 25c pack that has IR numbers around 12 per cell. Its been that way since new and not is not a cheap HK brand. I have another 25c pack that shows IR numbers below 4. Both hold voltage under load equally well. Which IR is correct? How can these two packs have the same C rating?

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05-13-2011 02:48 AM  7 years agoPost 19
rexxigpilot

rrProfessor

Florida

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Gregor99, you're absolutely correct. IR is not the only indicator of high C capability. It is just one of the variables. Many other factors come in to play. The C rating is just a measure of how much current can be provided before damage to the pack occurs.

One thing folks need to know about IR is that it is lower on larger packs and higher on smaller packs due to physical dimensions of the current flow path. Battery chemistry means a lot too.

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05-13-2011 03:34 AM  7 years agoPost 20
Ace Dude

rrProfessor

USA

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I hope you are aware that holding voltage under load is a function of the IR. The lower the IR the less voltage drop under load - Ohm's law.
I'm well aware of Ohm's law and the proper application of Ohm's law.
Regarding pack life, if you read my post carefully you would have noticed the almost 100 flights/cycles part.
I read your post. Almost 100 flights doesn't impress me. I don't recall your post showing any comparative data of one your HK packs versus a premium TP or Hyperion pack at say 50, 100, 150, and perhaps 200 cycles at various discharge rates.

Looks like your response also forgot to include your list of the "few" LiPo factories you're aware of that exist. Perhaps you can even tell us which brands are made in which factories.

  

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