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Salt water baths DO NOT WORK for lipo disposal

Old 11-05-2006, 07:23 AM
  #1  
Larry3215
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Default Salt water baths DO NOT WORK for lipo disposal

I have posted this before on RC Groups with pictures but here is more proof.

I had a 3S 1320 pack that had suffered some minor crash damage, then got over discharged and it finally puffed very slightly.

I decided to do one more test of the "salt water bath" urban ledgend that keeps croping up over and over and over again.

This pack was about 1/2 charged when I dumped it into a 1 quart mason jar 3/4 filled with salt water. Its been in there for the entire summer because I forgot about it untill tonight.

Its been so long all the salt water evaporated.

I just desected the pack and ALL THREE of the positive aluminum tabs are completely erroded from the cells.

Tomorrow I will take the pack outside and puncture it to see how much stored energy is still in the cells.

DONT use salt water to discharge cells or packs for disposal!!

It does not work.

The red circles in these pictures show the positive tabs - they are all gone.

Larry
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Old 11-05-2006, 12:16 PM
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Once again you have proven that salt eats aluminum!!!!!!

Anyone that has had a boat and ran it on the ocean could have told you that. We have known it for years.

The last thing you do before putting your boat up after using it is flush the motor system to get the salt water out of it to prevent corrosion. The wash the rest of the boat to remove any residue from the metal fixtures on the hull to prevent corrosion and the "tabs" from disappearing.

Great job!!!!!

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>
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Old 11-05-2006, 07:28 PM
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I think a bigger warning would be this:

Do NOT put a LiPo battery in a glass container!

Whether the salt water worked or not, if that LiPo decided to have a sudden catastrophic failure then the glass jar would have exploded. If anyone would have been near it when it blew apart, then they'd definitely get hurt. Always store LiPo batteries out in the open (like on a concrete floor or on a concrete block) and away from flammable materials, observe damaged LiPo batteries in a fireproof open container (like a bowl or pail), and dispose of LiPo batteries in a fireproof open container that is full of salt water.

The reasoning behind putting LiPo batts in salt water is simply because the salt helps to make the water more conductive. Immersed in salt water, the cells of a LiPo will slowly discharge until they're completely dead. Each cell will discharge evenly, since each cell's interconnects would be exposed to the salt water solution. The current from one cell wouldn't need to travel through an adjacent cell, which lessens the risk of running current through a damaged cell (and heightening the risk of fire or explosion). And if a runaway reaction does occur, then the battery is already in water!

The reason the aluminum interconnects were gone is because of the electrolytic action of the discharging cells. Electroplating is done using this same method - Metal ions detatch from the positive electrode and are deposited onto the negative electrode, thus coating the negative electrode with the metal that made up the positive electrode. The aluminum was simply taken off one set of interconnects and ended up on the other interconnect.

Another way to see electrolysis in action is to stick a 9-volt battery in a salt water solution (you'll see bubbles of gas boil off its terminals). If you're using salt water as the electrolyte, then the gas emitted from each battery terminal will be hydrogen and chlorine. If you're using dilute acid (hydrochloric, sulfuric, etc) as the electrolyte, then the gas emitted will be hydrogen and oxygen.

---

Alrighty, that was a pretty long-winded explanation, don'cha think?
By looking at the logic behind the idea, plunking a dead or damaged LiPo in an open container (like a bowl or pail) of salt water seems like the right thing to do. But putting it in a restricted glass container (like a jar or bottle) is not a safe thing to do.
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Old 11-05-2006, 08:42 PM
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*sigh* this old wives tail is sure hard to kill.

You obviously didnt read my post or look at the pictures above.

Putting the packs in salt water DOES NOT DISCHARGE THE PACK.

Instead, it corrodes away the aluminum tabs long before it can discharge the pack.

The discharging stops when the tabs are gone.

Do NOT put your charged packs in salt water - no matter what type of container you use. It will not discharge the pack!!!!!!!!!!!!!!!!!!!!!!

Please - do a Google for "galvanic corrosion".

It takes salt water, aluminum (in this case) and a current flow for the tabs to errode.

Get some salt water and put a piece of aluminum in it and see how long it lasts - years.

Run a small current thru that same piece of aluminum and it will be gone in a few minutes - at which point the current stops.

Good luck gentlemen.

Larry
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Old 11-05-2006, 09:14 PM
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Someone someday had GOT to see what happens with a lipo in a microwave.
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Old 11-05-2006, 09:23 PM
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That's a good idea Forest... let us know how it turns out!


just kidding of course!


really...



I mean REALLY!!!
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Old 11-05-2006, 10:03 PM
  #7  
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Originally Posted by Larry3215 View Post
I have posted this before on RC Groups with pictures but here is more proof.

I had a 3S 1320 pack that had suffered some minor crash damage, then got over discharged and it finally puffed very slightly.

I decided to do one more test of the "salt water bath" urban ledgend that keeps croping up over and over and over again.

This pack was about 1/2 charged when I dumped it into a 1 quart mason jar 3/4 filled with salt water. Its been in there for the entire summer because I forgot about it untill tonight.

Its been so long all the salt water evaporated.
I just desected the pack and ALL THREE of the positive aluminum tabs are completely erroded from the cells.

Tomorrow I will take the pack outside and puncture it to see how much stored energy is still in the cells.

DONT use salt water to discharge cells or packs for disposal!!

It does not work.

The red circles in these pictures show the positive tabs - they are all gone.

Larry
The salt water bath works only if you do it properly. That is, you must first discharge the pack completely by putting a low load (never a dead short) across the pack such as a motor, light bulb, or resistor and let it sit until the pack reads zero volts. Then use a new # 11 blade to slice a very small incision through the outer pouch along an edge where you can not stick the blade into the plates. ONLY THEN- drop the cells/pack into salt water. You may see a few bubbles appear in the water and maybe not. Let it sit for 24 hours (not until the water evaporates!) and you can dispose of the cells/pack in the trash. Don't tell me this does not work as I have done it many times. I have even dissected a pack so neutralized and stuck the plates in a torch flame to see if they ignited. All that happened is that a pretty green flame pattern appeared as the copper was heated. Not old wives tales but proven empirically. Yes, if you just drop a cell in salt water, you have done half the job and it won't work.
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Old 11-05-2006, 10:29 PM
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Exactly.

Use any other method to discharge the packs - except salt water.

Thanks Fred.

Larry
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Old 11-05-2006, 11:03 PM
  #9  
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Originally Posted by Larry3215 View Post
Exactly.

Use any other method to discharge the packs - except salt water.

Thanks Fred.

Larry
I think in this case you should rename the title of the thread. As it is now you thread says salt water does not work for Lipo disposal. But it was shown in a previous post, and you didn't dissagree, that it does. However what it does not do is discharge the lipo for you. I'm not sure the reason for the salt water but I have read from a couple of manufacturers the exact set of "rules" as listed above. connect the the battery to a load to discharge it. then cut the pack to allow salt water to engage the plates. Then let it soak for 24. I think the title of the thread should reflect that Salt Water does not work for Discharging, which as stated above, is only half of the proper disposal method.
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Old 11-05-2006, 11:35 PM
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Originally Posted by firemanbill View Post
That's a good idea Forest... let us know how it turns out!


just kidding of course!


really...



I mean REALLY!!!
I do have a microwave we'll be retiring soon.
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Old 11-05-2006, 11:49 PM
  #11  
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What is the risk to anyone who has no real chemical or electrical knowledge when he just cuts thru the plastic cells because it is so obvious to just cut them open and let the water in?
Many Have no interest or equipment to do the needed steps.

Engine runs slow. Buy new pack. Throw old one in the trash. Life is really that simple for 1,000's of flyers.
Garbage truck compacts them. Poof. Who really cares?

That is the risky step to LIPOS.

No high energy source can be made safe. Increasing power densities mean more violent chemical reactions. No mystery.

How many of you remember the " story" of the gallon of Nitromethane that blew up while being moved after sitting in a garage for years. They never came up with a answer. " Just be more carefull about long term storage. "
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Old 11-06-2006, 02:04 AM
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Originally Posted by ForestCam View Post
I do have a microwave we'll be retiring soon.

well get a video of if you do. from a long way away of course!
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Old 11-06-2006, 02:05 AM
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Originally Posted by Cyclops View Post
Engine runs slow. Buy new pack. Throw old one in the trash. Life is really that simple for 1,000's of flyers.
Garbage truck compacts them. Poof. Who really cares?

"
That really is the dangerous part!
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Old 11-06-2006, 02:19 AM
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I just went through all that with the 3S 2100 lipo I crashed in my Spitfire. Put a light bulb on it to discharge. Reading on all three cells before I hooked up the bulb was 3.9 volts. After the discharge was 0, 0, 0 volts. Put a small slit in each cover and soaked in salt water for 24 hours and pitched it.

Seemed like a lot of work but I sure didn't want it to be dangerous to anyone.
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Old 11-06-2006, 02:56 AM
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Originally Posted by Larry3215 View Post
Exactly.

Use any other method to discharge the packs - except salt water.

Thanks Fred.

Larry
Why are you thanking Fred?

He just told you to finish the job with SALT WATER!

"Let it sit for 24 hours (not until the water evaporates!) and you can dispose of the cells/pack in the trash. "

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
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Old 11-06-2006, 12:07 PM
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Originally Posted by ForestCam View Post
Someone someday had GOT to see what happens with a lipo in a microwave.
Might as well throw in a cat if you have one handy.

Some of the kids do that, I read somewhere.


I think I'm kidding??


ADDED: Could put it all in the back of a Suburban, then try it.





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Last edited by ragbag; 11-06-2006 at 12:09 PM. Reason: ADDED INFO
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Old 11-06-2006, 03:27 PM
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Tomorrow I will take the pack outside and puncture it to see how much stored energy is still in the cells.
Larry,

I've read the thread twice now and maybe I missed it, but did you ever do this? Was there any energy left in the pack?

I also must call into question the assertion that the tabs will be gone "in a few minutes." You left the pack in salt water for months, and the severe tab corrosion is to be expected. Were they really gone that quickly? I thought you dunked the pack and neglected it for months. Did you perform tests after the fact to see how long the tabs would last?

I've been spreading this alleged "myth" for years based on the recommendations of those who sell the batteries. Over that time people have often misunderstood the real reason for the dunking (they usually thought it somehow "neutralized" the lithium), but this is the first time I have ever seen the practice itself attacked.

If there is some scientific proof that all salt water does is eat the tabs off without actually discharging the pack, I will gladly stand corrected.

However, your assertion at this point can be boiled down to, "I left the pack soaking for months, and the tabs are eaten away. Therefore, salt water baths do not work for lipo disposal." It's not a logical conclusion to draw with the information provided to this point.

So far, it does not appear that you have stated whether or not the pack was discharged. If the pack is indeed discharged, then your conclusion is incorrect. Please let us know if the pack is discharged or not.

The only myth I see in this thread is the one about putting the battery in a glass container. There are a few Mythbuster-esque corner cases where if you purposely put a shorted-out LiPoly in a weak glass container, and sealed it up, that it would turn into a "grenade" due to the pressure buildup from the combustion gasses. However, in a salt water bath in a nice strong OPEN Mason jar, there is no absolutely no danger of it turning into a "grenade." Under water, the pack can't get oxygen to burn in the first place. Even if the pack could burn under water, there would be no pressure buildup because the jar is open. The pack itself would have to explode, and that in and of itself is a myth that has proven to be false: LiPoly packs may burn violently but they do not explode in the scientific sense.
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Old 11-06-2006, 05:08 PM
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Matt, you are right on the money.

The alu tabs won't be eaten overnight. The water will discharge the battery long before that. Water is a pretty good conductor and salt increases the conductivity even more.

I have to disagree with Larry, the water trick discharges the battery in a controlled manner.
If you discharge the batteries to zero with a light bulb or any other means then there is no point in throwing them into salt water....

BoKo
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Old 11-06-2006, 05:30 PM
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Put it out on the rock out back, half a dozen .177 pellets at 1000 fps, soak in the bucket of water overnight, toss in the trash
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Old 11-06-2006, 06:21 PM
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It wasn't that long ago someone posted a pic of an un-discharged pack nailed to a tree.
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Old 11-07-2006, 12:45 AM
  #21  
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Originally Posted by Driver330 View Post
Matt, you are right on the money.

The alu tabs won't be eaten overnight. The water will discharge the battery long before that. Water is a pretty good conductor and salt increases the conductivity even more.

I have to disagree with Larry, the water trick discharges the battery in a controlled manner.
If you discharge the batteries to zero with a light bulb or any other means then there is no point in throwing them into salt water....

BoKo
Sorry to disagree, but the purist of water is an insulator or my instructors way back in 1955 were wrong. It is the impurities in the water, salt, that are the conductors. That is the reason to add the salt.

If you add water to a wet cell and it is not distilled it will short the plates in a lead acid battery.



>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> >>>>
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Old 11-07-2006, 02:05 AM
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http://www.rcgroups.com/forums/showt...t=510204&pp=53


Originally Posted by Matt Kirsch View Post
Larry,

I've read the thread twice now and maybe I missed it, but did you ever do this? Was there any energy left in the pack?
Matt is refering to this thread:

http://www.rcgroups.com/forums/showthread.php?t=592509

Yes I did do the test and yes there was still energy in the cells - enough to heat some water significantly. Se post 15.

I also must call into question the assertion that the tabs will be gone "in a few minutes." You left the pack in salt water for months, and the severe tab corrosion is to be expected. Were they really gone that quickly? I thought you dunked the pack and neglected it for months. Did you perform tests after the fact to see how long the tabs would last?
Matt - did you go back to the original thread I did on this same subject?

http://www.rcgroups.com/forums/showt...t=510204&pp=53

In that thread - starting on about post 53 - I did a series of tests - with photos and watt meter readings - showing just how fast the tabs would errode. I also tested some large chunks of aluminum and copper wire. NONE of them lasted more than 30 minutes - even relatively large chunks of solid aluminum many times the size of a lipo tab.

In addition - this pack in this thread is the third pack I have opened up after sitting in salt water. ALL three still had significant amount of charge left in them and all three had ALL the positive tabs gone completely

The reason I left this sooooo long was not specifically to show that the tabs would be gone, but to show that the cells in the pack would NOT be discharged - even after 3 months.

The tabs were gone within minutes.

There is a simple test you can do to prove this to yourself. See post 29 for details of how to do it. Its fast and easy and very informative.

http://www.rcgroups.com/forums/showp...3&postcount=29




I've been spreading this alleged "myth" for years based on the recommendations of those who sell the batteries. Over that time people have often misunderstood the real reason for the dunking (they usually thought it somehow "neutralized" the lithium), but this is the first time I have ever seen the practice itself attacked.
So far as I know - NO lithium pack manufacturors still recomend this and no retailers still recomend this practice. If you can find one please let me know

If there is some scientific proof that all salt water does is eat the tabs off without actually discharging the pack, I will gladly stand corrected.
Google "galvanic corrosion" and also see my three examples in the above two threads. Not "scientific" proof, but Im batting 100%.

Also, as I said NO manufactorors still make that recomendation that I have been able to find.


However, your assertion at this point can be boiled down to, "I left the pack soaking for months, and the tabs are eaten away. Therefore, salt water baths do not work for lipo disposal." It's not a logical conclusion to draw with the information provided to this point.

So far, it does not appear that you have stated whether or not the pack was discharged. If the pack is indeed discharged, then your conclusion is incorrect. Please let us know if the pack is discharged or not.
See my comments above

The only myth I see in this thread is the one about putting the battery in a glass container. There are a few Mythbuster-esque corner cases where if you purposely put a shorted-out LiPoly in a weak glass container, and sealed it up, that it would turn into a "grenade" due to the pressure buildup from the combustion gasses. However, in a salt water bath in a nice strong OPEN Mason jar, there is no absolutely no danger of it turning into a "grenade." Under water, the pack can't get oxygen to burn in the first place. Even if the pack could burn under water, there would be no pressure buildup because the jar is open. The pack itself would have to explode, and that in and of itself is a myth that has proven to be false: LiPoly packs may burn violently but they do not explode in the scientific sense.
I agree

Larry
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Old 11-07-2006, 02:11 AM
  #23  
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Originally Posted by Driver330 View Post
Matt, you are right on the money.

The alu tabs won't be eaten overnight. The water will discharge the battery long before that. Water is a pretty good conductor and salt increases the conductivity even more.

I have to disagree with Larry, the water trick discharges the battery in a controlled manner.
If you discharge the batteries to zero with a light bulb or any other means then there is no point in throwing them into salt water....

BoKo
Sorry, but the only thing that I agree with here is that there is no point in throwing them in the salt water.

Try the test I talked about above for yourself. Its easy and positive proof that what Im saying is 100% true.

See if you can find a single recomendation from a lipo manufactiror or retailer on how to discharge or dispose of lipos that says to use salt water to discharge the packs.

There are none.

Its an old wives tail.

Dont do it.

Larry
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Old 11-07-2006, 02:13 AM
  #24  
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Well ,I may as well stir the pot up.

(A) A Lipo is a mixture of chemicals that can and do go into THERMAL RUNAWAY when short circuited or crushed to the point that the chemicals physically begin touching each other when charged.

That most would agree upon.

(B) Are there any chemical engineers that know for a absolute fact that a completly discharged cell will NOT go in to thermal runaway ?

That is a fact I have never see anyone back up with proof.

If (A) is true, all that is needed is a complete discharge.

Am I making this too simple ?
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Old 11-07-2006, 02:14 AM
  #25  
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Well ,I may as well stir the pot up.

(A) A Lipo is a mixture of chemicals that can and do go into THERMAL RUNAWAY when short circuited or crushed to the point that the chemicals physically begin touching each other when charged.

That most would agree upon.

(B) Are there any chemical engineers that know for a absolute fact that a completly discharged cell will NOT go in to thermal runaway ?

That is a fact I have never see anyone back up with proof.

If (B) is true, all that is needed is a complete discharge.

Am I making this too simple ?
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