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Old 09-26-2012, 09:18 AM   #1
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Questions?? One For The Chemists (Lipo Discharging Question)

As a responsible club, when someone has a problem with a lipo we put in a container of saline solution to discharge it. When we next come to race the packs are then removed and put into the electronic recycling at my work.

When the salt water solution is first created it is nice and clear and you can see the negative battery terminals fizzing.

After a few packs have been put through it, the solution turns cloudy and a thin, pale blue sludge appears in the water.

Can anyone tell me what the blue sludge is.

As the water is acidic, is there electrolysis occurring and producing something alkaline?

As you've guessed, I haven't done any chemistry since school and can remember very little of it.

Thanks
Skiddins
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Old 09-26-2012, 05:20 PM   #2
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Quote:
Originally Posted by Skiddins View Post
As a responsible club, when someone has a problem with a lipo we put in a container of saline solution to discharge it. When we next come to race the packs are then removed and put into the electronic recycling at my work.

When the salt water solution is first created it is nice and clear and you can see the negative battery terminals fizzing.

After a few packs have been put through it, the solution turns cloudy and a thin, pale blue sludge appears in the water.

Can anyone tell me what the blue sludge is.

As the water is acidic, is there electrolysis occurring and producing something alkaline?

As you've guessed, I haven't done any chemistry since school and can remember very little of it.

Thanks
Skiddins
Just what i know from grade 10 high school science;
Lithium is an alkali metal which would produce a reaction when placed in sodium solution probably producing some form of sodium (e.g. sodium chloride etc... hope you get what i mean). But correct me if I'm wrong, eager to learn about chemistry.
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Old 09-26-2012, 05:31 PM   #3
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http://wiki.answers.com/Q/What_happe..._in_salt_water

Could just be the oxidization from the terminals in the battery? Is the bluish color the same bluish color you see when copper oxidizes? Do they even use copper for the battery terminals?

-Mike
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Old 09-26-2012, 06:13 PM   #4
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http://wiki.answers.com/Q/What_happe..._in_salt_water

Could just be the oxidization from the terminals in the battery? Is the bluish color the same bluish color you see when copper oxidizes? Do they even use copper for the battery terminals?

-Mike
That's what I was thinking. Copper terminals corroding. The lithium should be contained within the cell wrapper, otherwise it would react violently with the water.
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Old 09-26-2012, 06:26 PM   #5
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Now you mention it, one of the terminals always disintegrates as the process goes on (I'm going to presume the one that vanishes is the same one that appears to be fizzing during the discharge.
From a full charge, the packs take a few days to discharge, so plenty of time to corrode anything

Yes, the terminals and plugs we use tend to be copper with gold plate etc on them to help prevent corrosion.

SO it sounds likely that the sludge is in fact copper paste or something
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Old 09-27-2012, 03:59 AM   #6
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SO it sounds likely that the sludge is in fact copper paste or something
Copper Chloride:

http://en.wikipedia.org/wiki/Copper%28II%29_chloride
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