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Old Aug 14, 2011, 09:24 PM
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United States, TN
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Lipo Pack Failure - What Kind Of Warning Signs Are There?

Are there any warning signs that a Lipo pack is starting to fail other than no longer taking a charge? If so what are the signs and can they be ranked in order of priority.

Thank you.
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Old Aug 14, 2011, 09:38 PM
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rcalldaylong's Avatar
San Jose, California
Joined Dec 2007
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Quote:
Originally Posted by itsme2 View Post
Are there any warning signs that a Lipo pack is starting to fail other than no longer taking a charge? If so what are the signs and can they be ranked in order of priority.

Thank you.

The obvious sign is puffing...but that only says the lipo is damaged in some way. I have lipos that are puffed, but put out great "C" ratings and take their full mah stated values.

For me, it's voltage sagging that is first sign, basically where a lipo no longer put out the high "C" ratings...Most of these lipos can still be fully charged and will still take a good charge up to close to it's mah stated values, but it is a quick downhill from there.
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Old Aug 14, 2011, 09:51 PM
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Originally Posted by rcalldaylong View Post
The obvious sign is puffing...but that only says the lipo is damaged in some way. I have lipos that are puffed, but put out great "C" ratings and take their full mah stated values.

For me, it's voltage sagging that is first sign, basically where a lipo no longer put out the high "C" ratings...Most of these lipos can still be fully charged and will still take a good charge up to close to it's mah stated values, but it is a quick downhill from there.
Do you ever see sudden failures that cause planes to crash?
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Old Aug 14, 2011, 10:00 PM
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San Jose, California
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Originally Posted by itsme2 View Post
Do you ever see sudden failures that cause planes to crash?
While possible, it's rare.

Personally I have not. This has happened to me though, but only because I ignored the sagging issues- Lipo was no longer able to provide enough juice and ESC cut power to motor completely. When a Lipo gets bad enough, you can charge up to full max, and when you WOT, voltage will drop dramatically below 9v and LVC will kick in and kill the motors.
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Old Aug 15, 2011, 06:56 AM
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Another sign is excess heat buildup. As the batteries age, their internal resistance increases resulting in greater dissipation during discharge. I've never had a battery completely fail either (so far ). There has always been at least enough voltage to run the receiver and servos.
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Old Aug 15, 2011, 11:12 AM
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Haralson County GA. USA
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Most often the first thing noticed if one pays attation to balanced charging is that the CV stage takes longer and longer and the cells are harder to balance. Next thing is that cells lose voltage faster when setting for 8 hours or more. Next is capacity is deminished so the power drop during a flight comes sooner and sooner.


Most sudden failiures during a flight is due to a bad solder connection which causes severe over heating and the joint (solder point) fails or a balancing leads comes lose and shorts out a cell .

Charles
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