Thunder Power 65C lipo with very high resistence - RC Groups
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Jan 31, 2013, 02:39 PM
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Thunder Power 65C lipo with very high resistence


I bought 8 Thunder Power 6s 7700 65C lipos about four months ago. I have finally finished the plane they are going in and am now charging them (kept at storage charge up until now). The packs will be used in series for 12s.

I noticed that one 6s pack has much higher resistence, 8 to 10 times higher, than the other packs. In addition to high resistence, my charger has a very hard time balancing this pack.

I have tried using different charging cables, different ports on my charger, two different chargers, I get the same result.

Has anyone encountered this problem before, and is there anything I can do other than return the pack to Thunder Power?

Thanks
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Jan 31, 2013, 02:48 PM
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Not uncommon to have variability. Far less common with quality packs (TP, Hyperion, etc.).

Absolutely nothing can be done to improve it other than returning to TP for warranty replacement.

Mark
Jan 31, 2013, 04:21 PM
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I'm most concerned with the huge variance in resistence.

I have contacted Thunder Power about this issue. I was just wondering if anyone had encountered a similar issue and knew of a solution.
Last edited by malcolmm; Jan 31, 2013 at 07:07 PM. Reason: accuracy
Jan 31, 2013, 07:14 PM
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Quote:
Originally Posted by malcolmm
I'm most concerned with the huge variance in resistence.

I have contacted Thunder Power about this issue. I was just wondering if anyone had encountered a similar issue and knew of a solution.
Only solution is to replace the pack, its a dud, happens to all of them.
Dec 24, 2016, 11:14 AM
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Ir resistance with lipos !


WHAT IS AN ACCEPTABLE VALUE FOR SAY A 3S 2250 65C LIPO-- FOR internal resistance--I measured a brand new Venom-3s 65c--7-8 m-ohm. Is there a chart somewhere available ?

Thanks,

Bob
Dec 24, 2016, 11:37 AM
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No chart bill .. im sure someone will have a link maybe?..
7-8 mohm is ok range with a 65c it will run alittle higher but ok..
i have a few in the 12mohm range that are great..they do go down while in charge mode..
Mar 04, 2017, 11:35 PM
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brushless55's Avatar
Quote:
Originally Posted by BIGBOB4877
WHAT IS AN ACCEPTABLE VALUE FOR SAY A 3S 2250 65C LIPO-- FOR internal resistance--I measured a brand new Venom-3s 65c--7-8 m-ohm. Is there a chart somewhere available ?

Thanks,

Bob
Smaller packs have higher IR #s vs bigger capacity
some of us have found IR values are very inconsistent anymore with judging a batteries performance vs real world use..

I would not worry about it and have fun
Mar 08, 2017, 11:35 AM
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Dennis C's Avatar
Quote:
Originally Posted by brushless55
Smaller packs have higher IR #s vs bigger capacity
some of us have found IR values are very inconsistent anymore with judging a batteries performance vs real world use..

I would not worry about it and have fun
I have been using the Lipo performance tool to compare and keep track of my packs This is the first post I have seen that does not consider IR as an important means of checking and comparing packs.

What do you consider inconsistent?

Dennis
Mar 08, 2017, 02:56 PM
Registered User
It really is just simple physics; higher IR means larger voltage drop, means lower voltage to the motor which must result in less power at the prop.
It is also a square law so that 5% less voltage will result in approx. 10% less power so that a small voltage drop is important.

Unless the laws of physics have changed recently, anyone who says IR is irrelevant are just deceiving themselves.

Wayne
Mar 08, 2017, 03:23 PM
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brushless55's Avatar
from my original comment...
Quote:
Originally Posted by BIGBOB4877
WHAT IS AN ACCEPTABLE VALUE FOR SAY A 3S 2250 65C LIPO-- FOR internal resistance--I measured a brand new Venom-3s 65c--7-8 m-ohm. Is there a chart somewhere available ?

Thanks,
Bob
Smaller packs have higher IR #s vs bigger capacity
some of us have found IR values are very inconsistent anymore with judging a batteries performance vs real world use..

I would not worry about it and have fun


Quote:
Originally Posted by Dennis C
I have been using the Lipo performance tool to compare and keep track of my packs This is the first post I have seen that does not consider IR as an important means of checking and comparing packs.

What do you consider inconsistent?

Dennis
Dennis, there are a few of us who have talked about this over the past 18months...
we have not talked about it much because a few hover around and try and prove us wrong with no success on their part.. so we don't say much about anymore.. Way to many battery Gods floating around the forums who try and disprove what a few have founds in battery testing... one reason my ignore list has gotten bigger...
It's kind of hard to explain but if you look at the battery testing thread you'll see several of us have come to similar conclusion about IR numbers and we no longer really care about those anymore we're more interested in the real world performance

Not an idea but something we've actually found to be true.

Most all high IR numbers will produce lower power vs lower IR numbers of the same pack.. if you have two packs and one has much higher numbers its a possibility it will be down on performance..
but manufacture vs manufacture, label vs label, things are hard to add up vs real world performance

We just had a lot of inconsistency and no longer consider those numbers as a tool for us to really worry about anymore and picking batteries.

For a long time so many people put way too much importance in that mainly because you already have the battery and what does it even matter to check those numbers anyway just go ahead and use it have fun with it.
Last edited by brushless55; Mar 08, 2017 at 03:41 PM.
Mar 08, 2017, 03:43 PM
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Dennis C's Avatar
you still did not address the Lipo objective performance calculator which does take into account the difference in IR due to capacity.

I have to say that this is the only report I have seen that tries to debunk IR as a valid way to compare pack performance

Dennis
Mar 08, 2017, 03:46 PM
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Dennis C's Avatar
Quote:
Originally Posted by Wayne Giles
It really is just simple physics; higher IR means larger voltage drop, means lower voltage to the motor which must result in less power at the prop.
It is also a square law so that 5% less voltage will result in approx. 10% less power so that a small voltage drop is important.

Unless the laws of physics have changed recently, anyone who says IR is irrelevant are just deceiving themselves.

Wayne
Thanks I always try to give some one a chance to clarify their position so far no clarity

Dennis
Mar 08, 2017, 03:53 PM
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brushless55's Avatar
Quote:
Originally Posted by Dennis C
you still did not address the Lipo objective performance calculator which does take into account the difference in IR due to capacity.

I have to say that this is the only report I have seen that tries to debunk IR as a valid way to compare pack performance
Dennis
sorry dude
I already made a comment about smaller packs almost always having higher IR numbers vs greater capacity..
not directed at you at all...
but I don't argue any of this anymore because their are trolls who follow me and a few others about IR numbers, and we don't talk much about my battery testing along with a few others because of the constant controversy with out finds in real world testing...
I would suggest reading around and you will find more about it, only if you care to

have a great day
Mar 08, 2017, 03:56 PM
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brushless55's Avatar
......................
Mar 08, 2017, 08:23 PM
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Quote:
Originally Posted by malcolmm
I'm most concerned with the huge variance in resistence.

I have contacted Thunder Power about this issue. I was just wondering if anyone had encountered a similar issue and knew of a solution.
I think we've all encountered weak or failing cells at one time or another, if it was an old pack id probably use it as a power bank. As others have said with a new pack it's better to simply return for refund or replacement.


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