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Old 02-25-2013, 06:28 PM   #1
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Questions?? Reducing Internal Resistance On Older Lipo's

Is there any way to reduce the internal resistance on a pack of lipo cells?

A couple of mine have shot up resistance wise and was wondering if there was any way back for them?

Thanks
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Old 02-25-2013, 06:45 PM   #2
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1) Open wallet and pull out credit card
2) Order new ones
3) Count your blessings that we do this less often than with NiMh's

... But I'll be watching this thread to see if anybody has found a way!
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Old 02-26-2013, 01:31 AM   #3
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Quote:
Originally Posted by Skiddins View Post
Is there any way to reduce the internal resistance on a pack of lipo cells?
Yes !!!

Find out the Internal resistance of each cell
Yes, open them up and wire in a resistor (parallel) the of the same resistance across each cell
You have now halved the batts total internal resistance

If you actually try this, sell all your RC gear and get a car that you pull along with a length of string.

OK, sensible answer.
Open up the batt pack & remove all the cells. Buy a new high C softpack & put those cells in the hardcase
If you actually try this, sell all your RC gear and......
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Old 02-26-2013, 02:21 AM   #4
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The IR of a lipo cell is determined by the chemistry and materials used in its manufacture and will change through the life of the cell because of degradation of same said chemicals and materials.

There is nothing you can do at all to change this, other than buy a new pack. If you packs have desegregated sufficiently, buy news ones and make these your practice packs.
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Old 02-26-2013, 02:56 AM   #5
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is there a way to put back the flavour in a chewing gum? In all honesty, I would really like to know
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Old 02-26-2013, 03:07 AM   #6
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Nice to see the asylum has let so many of you out today.

Thanks RogerDaShrubber
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Old 02-26-2013, 08:38 AM   #7
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Quote:
Originally Posted by Dread Pirate View Post
1) Open wallet and pull out credit card
2) Order new ones
3) Count your blessings that we do this less often than with NiMh's

... But I'll be watching this thread to see if anybody has found a way!
LOL!

This is true!
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Old 02-26-2013, 08:43 AM   #8
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You can always heat them up....
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Old 02-26-2013, 09:14 AM   #9
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I hear driving a nail through them is the "hot" ticket.



Sean
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Old 02-26-2013, 09:26 AM   #10
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You can always heat them up....
X2
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Old 02-26-2013, 09:34 AM   #11
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Quote:
Originally Posted by 1101 View Post
Yes !!!

Find out the Internal resistance of each cell
Yes, open them up and wire in a resistor (parallel) the of the same resistance across each cell
You have now halved the batts total internal resistance

If you actually try this, sell all your RC gear and get a car that you pull along with a length of string.

OK, sensible answer.
Open up the batt pack & remove all the cells. Buy a new high C softpack & put those cells in the hardcase
If you actually try this, sell all your RC gear and......
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Old 02-26-2013, 10:19 AM   #12
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Not sure if it's possible but these info might help on how to, at least, extend their peak life cycle.

http://www.gibbsguides.com/lipoguide.htm

http://www.mpoweruk.com/testing.htm

http://data.energizer.com/PDFs/BatteryIR.pdf

http://www.slkelectronics.com/ecalc/lithium.htm

On the last two links, it is discussed how temperature affects the internal resistance of both Alkaline and Lipo bateries. Based on
the information, the internal resistance of a Lipo batt DECREASES as the battery gets hotter.

So, the answer is take your wife's or girlfriend's hair blower and take it to the races with you and heat those suckers before charging! (just kidding!)
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Old 02-26-2013, 11:47 AM   #13
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Quote:
Originally Posted by RogerDaShrubber View Post
The IR of a lipo cell is determined by the chemistry and materials used in its manufacture and will change through the life of the cell because of degradation of same said chemicals and materials.
1. Buy said chemicals
2. Buy 2 heavy duty hypodermic needles

Rest is pretty easy to figure out.
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Old 02-26-2013, 12:48 PM   #14
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Give them a full charge, toss them in a bucket of water, and wait for chemicals to start bubbling. After water is not longer bubbling, battery should be completely toast and have an IR of 0

LOL don't actually try this...
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Old 02-26-2013, 01:34 PM   #15
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Quote:
Originally Posted by JamesL_71 View Post
You can always heat them up....
100% true, Discharge them from their storage voltage to 3.1 volts. They should be quite toasty. Immediately begin charging them, and run them ASAP after charging. They'll run noticeably better, but a fresh pack will still be significantly faster.
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