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LI-ion cells-one more time

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Forum Archives 2010 - » Archive through 13 January, 2012 » LI-ion cells-one more time « Previous Next »

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rob_guyer
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Username: rob_guyer

Post Number: 24
Registered: 08-2011

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Posted on Friday, 06 January, 2012 - 06:51 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Twenty years or more ago, a contributor to "Wireless World" magazine partially restored worn NICAD cells which had become dehydrated because repeated warm/cool cycles had caused expansion/contraction of the enclosed nitrogen gas resulting in a loss of water vapor through the breather holes. He injected 1-2 ml of deionised water back through the septum and reported encouraging results. Has any Poster heard if this works with LI-ion cells?
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terry
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Username: terry

Post Number: 642
Registered: 05-2005

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Posted on Friday, 06 January, 2012 - 07:56 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

No is the short answer, I believe they are sealed and dangrous if they leak.


Terry
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alexr
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Post Number: 196
Registered: 02-2008

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Posted on Friday, 06 January, 2012 - 08:15 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Lithium is VERY reactive with water and the electrolytes used in LI-ion batteries are NOT water based. Therefore trying to inject water into LI-ion battery would be a VERY VERY bad idea and would probably do serious damage both you and the battery!!!
Alex
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gordon
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Post Number: 744
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Posted on Friday, 06 January, 2012 - 12:07 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

When a Li-Ion goes bad, I think the electrodes suffer, rather than the electrolyte. As already posted, they are too dangerous to tamper with, better to get a replacement.
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rob_guyer
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Username: rob_guyer

Post Number: 25
Registered: 08-2011

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Posted on Saturday, 07 January, 2012 - 05:23 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Point taken- no further action. Just goes to show that chemistry and electronics are bad neighbors. My most perplexing equipment faults were brought on by dodgy chemical processes, and not just in cells and their close relatives, electrolytic capacitors.There could be a whole new thread here.
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dselec
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Username: dselec

Post Number: 373
Registered: 11-2010


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Posted on Saturday, 07 January, 2012 - 04:01 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Sorry i disagree with you rob/
i am woking in a field that works with chemicals mostly gases and they work wonders in electronic/components /micro electronics etc..etc..
cant even imagine life without electronics/chemicals.
as long as u know and accept the simple laws between both of them they are safe.
http://scifair.org/news/physics-news/using-chemistry-for-electronics-and-vice-versa.html
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rob_guyer
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Username: rob_guyer

Post Number: 26
Registered: 08-2011

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Posted on Saturday, 07 January, 2012 - 10:48 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

My posts often let brevity get in the way of clarity. Sorry about that. I should have said that well-intentioned, but poorly applied chemical processes can cause electronic equipment to behave in strange ways. An example;
Customer complained that the moving-coil meter needle in his elderly electronic millivoltmeter was "stuck at zero". Checked fuses OK, circuitry OK, applied a few microamps from my digital ohmeter to D'arsonval movement terminals- showed expected continuity- still OK, Eventually noticed many metal splinters, (dendrites?) filling the magnetic gap between magnet pole pieces and movement armature. Repaired "stuck" meter using a fine artists brush. Resolveed to listen next time to customer.
Cause thought to be faulty passivation of the cadmium plating intended to combat rust of steel horseshoe magnet. Others might have encountered similarly exotic faults.
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dselec
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Username: dselec

Post Number: 375
Registered: 11-2010


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Posted on Sunday, 08 January, 2012 - 08:06 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Yes i have rob.
u solved the riddle always wondered how/where did all that splinters came from .
thanks
dselec

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