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Old Dec 30, 2011, 10:38 PM
Expo is built into my thumbs
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Lipo in saltwater for fun and science Updated Jan 13

The old lipo in saltwater thing keeps showing up from time to time. Some people swear that it works and others swear that it doesn't work. I got in a debate about it again today so I decided to try it for myself and see what happens.

I found an older 3s 1300mah turnigy pack that is what I would call squishy. Its not puffed up bad just a little on the soft side. I grabbed the battery, an old empty ice cream buck and mixed up some salt water. Right now it is 19:30 on December 30 the battery has been in the salt water for about ten minutes. There are quite a few bubbles coming off the negative side of the deans connector and a few bubbles coming out of where the leads exit the shrink wrap. I am going to leave it in the saltwater bath for the next two weeks and see what happens. I will post updates along the way.

Edit: The battery was at storage voltage when I put it in the saltwater. I forgot to add that to the post.


Untitled by Hance1976, on Flickr


Untitled by Hance1976, on Flickr


Untitled by Hance1976, on Flickr


Untitled by Hance1976, on Flickr
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Last edited by Hance; Jan 13, 2012 at 01:47 PM.
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Old Dec 30, 2011, 10:38 PM
Expo is built into my thumbs
Hance's Avatar
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Joined Jul 2008
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OK its been two weeks or close enough to it. The battery went for a swim on the evening of Dec 30 and its now Jan 13 at about 12:30 PM. First off the deconstruction photos.

This is what the container looked like after two weeks. Notice the salt ring from water evaporation ?

DSCN2259 by Hance1976, on Flickr

Out of its bath and ready for an autopsy.


DSCN2260 by Hance1976, on Flickr

Outer shrink wrap removed.


DSCN2261 by Hance1976, on Flickr

Inner wrapper removed.


DSCN2262 by Hance1976, on Flickr

End of the battery/circuit board.


DSCN2263 by Hance1976, on Flickr

Circuit board exposed.


DSCN2264 by Hance1976, on Flickr

Circuit board exposed 2 notice the large amount of corrosion materials on everything.

DSCN2265 by Hance1976, on Flickr

Circuit board cleaned up


DSCN2266 by Hance1976, on Flickr


DSCN2267 by Hance1976, on Flickr

Separating the cells.


DSCN2267 by Hance1976, on Flickr


DSCN2270 by Hance1976, on Flickr

Volt meter and getting ready for the final testing.

DSCN2271 by Hance1976, on Flickr
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Old Dec 30, 2011, 10:39 PM
Expo is built into my thumbs
Hance's Avatar
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Now for the final testing. I knew the tabs on the battery have to exit between a couple of insulating layers and if I could somehow stick a probe between those two insulating layers I would be able to read if there was any voltage left in the battery pack. I busted out my trusty Fluke 87 volt meter, a couple of jumpers I have and stole a couple of push pins off my building board and I was ready to see if there was any voltage left in the pack.

I slipped the pins in where the tabs used to be like so and then hooked the jumpers up to my volt meter.


DSCN2272 by Hance1976, on Flickr

Cell one looked like so when I hooked it up. Its sitting at .581 volts so its not totally dead but close to it.

DSCN2274 by Hance1976, on Flickr

Cell two looked like so. Its sitting at .344 volts so it is slightly more discharged than cell number one but still not totally dead.

DSCN2275 by Hance1976, on Flickr

And finally we have cell number three. It was the center cell in the pack and the last cell I tested. It looked like so when I hooked the volt meter up. Cell number 3 had a little bit of a tab left sticking out so I didn't need to use the push pins on both tab on that cell.


DSCN2276 by Hance1976, on Flickr

HOUSTON WE HAVE A PROBLEM Thats right 3.74 volts so that cell only lost .1 volts over two weeks time. I don't think I even need to share my conclusion at this point.
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Old Dec 30, 2011, 10:48 PM
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So what is the final goal here?

To see if the pack has zero volts after 2 weeks?
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Old Dec 30, 2011, 10:51 PM
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What was the voltage of the pack before you started ?

Cheers
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Old Dec 30, 2011, 10:53 PM
Expo is built into my thumbs
Hance's Avatar
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Quote:
Originally Posted by TheWoodCrafter View Post
So what is the final goal here?

To see if the pack has zero volts after 2 weeks?
Exactly right. Thunderpower says saltwater bath for two weeks right on their website as the proper method to fully discharge a lipo. I had an old lipo that needs to be trashed anyway so I figured what the heck lets see what happens.


The battery has now been in the saltwater for 20 minutes there is what looks like grey smoke coming out of the shrink wrap where the leads exit the pack.

The battery was at storage voltage 3.85 per cell.
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Old Dec 30, 2011, 11:00 PM
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Electrolysis...

I forget the polarity, but the bubble stream off one of the leads will be pure oxygen gas and the other will be straight hydrogen.

Seal up the bucket and suck out as much air as you can, then open it in two weeks and light a match
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Old Dec 30, 2011, 11:06 PM
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Lets see what happens.

(don't do what TP16 suggests. I don't want to hear about any fires)
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Old Dec 30, 2011, 11:10 PM
Frankenstein recycled packs
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It won't be a fire. It will be an explosion.
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Old Dec 30, 2011, 11:12 PM
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As per TP's instructions

http://thunderpowerrc.com/PDF/DISPOS...-BATTERIES.pdf


The pack is supposed to be discharged as low as you can before throwing them into the Saltwater

It is not designed to discharge them, just make them safe for disposal

If left with a charge in them the tabs could corrode before they are energy depleted, meaning they are no longer landfill safe

Cheers
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Old Dec 30, 2011, 11:16 PM
Expo is built into my thumbs
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Quote:
Originally Posted by crusey_aus View Post
As per TP's instructions

http://thunderpowerrc.com/PDF/DISPOS...-BATTERIES.pdf


The pack is supposed to be discharged as low as you can before throwing them into the Saltwater

It is not designed to discharge them, just make them safe for disposal

If left with a charge in them the tabs could corrode before they are energy depleted, meaning they are no longer landfill safe

Cheers
Step one from thunder power states "1. If any LiPo cell in the pack has been physically damaged, resulting
in a swollen cell or a split or tear in a cellís foil covering, do NOT discharge the battery.
Jump to step 5."

The battery is squishy ie swollen I am following their directions to the letter
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Old Dec 30, 2011, 11:20 PM
Expo is built into my thumbs
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Quote:
Originally Posted by TP16 View Post
Electrolysis...

I forget the polarity, but the bubble stream off one of the leads will be pure oxygen gas and the other will be straight hydrogen.

Seal up the bucket and suck out as much air as you can, then open it in two weeks and light a match

Yes electrolysis is going on but the smoke as I called it is probably aluminum leaving the tabs of the battery.

I know more about electrolysis than almost anybody on this website I happen to be certified by the National Association of Corrosion Engineers www.nace.org to do corrosion protection work on underground structures to prevent corrosion. Its my day job
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Old Dec 30, 2011, 11:23 PM
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So the salt water will also rot a hole in the cells besides corroding off the tabs.

That should kill the battery.
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Old Dec 30, 2011, 11:31 PM
Expo is built into my thumbs
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Quote:
Originally Posted by TheWoodCrafter View Post
So the salt water will also rot a hole in the cells besides corroding off the tabs.

That should kill the battery.
I don't honestly know if it will corrode the tab off and stop leaving the battery partially charged or if it will breach the cell itself and totally discharge it. Once the two weeks is up I will remove the battery from the water and do an autopsy on it. I have a rather expensive volt meter than I use for work and I will probe each cell to see if any voltage remains. Thunderpower states it will fully discharge the battery that means 0 volts. If I can measure any voltage from any of the cells I would say the test is a failure because the battery is not fully discharged.
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Old Dec 31, 2011, 07:02 AM
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Quote:
Thunderpower says saltwater bath for two weeks right on their website as the proper method to fully discharge a lipo.
Thier website and LiPolyt Safety Sheet also states to charge at 1C ,yet they have LiPolys rated for up to 12C charge rates.

FYI I have tested LiPolys,balancers and chargers for TP for years and I am fully aware that much of thier website info is completely outdated.
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