How do you know when you’ve pierced a terminal bottom on an EVE 280Ah cell?

fafrd

Solar Addict
I’m interested in hearing from anyone who has accidentally pierced through the aluminum bottom of a terminal on an EVE 280Ah cell: what happens and how do you know the worst has befallen?

It’s probably a false alarm but I may just have pierced the bottom of one of my terminals and don’t know how to confirm the worst or prove I’m still OK.

I’ve been gluing stainless grubscrews into my 280Ah cells and my process involves:

1/ characterizing number of turns to bottoming ‘dry’ and noting that for each terminal (big range so, with maximum of 5-3/4 turns and minimum of 4-5/8ths turns).

2/ Applying some JB Weld into the bottom of the terminal and some more on the cupped end of the grubscrew and then starting to thread the grubscrew.

3/ Once the grubscrew bottoms into the liquid JB Weld, finger tighten with an Allen Head wrench until JB Weld begins oozing out of the thread at the terminal surface (typically tighten ~1/8th turn every minute or so), keeping track of number of ‘wet’ rotations versus the rotations to bottoming dry noted earlier.

4/ Continue applying turns/pressure slowly by hand until you hit the number of turns to bottom (at which point the grubscrew should be fully threaded to the bottom of the terminal).

It’s all been working out well and I believe I can ‘feel’ when the grubscrew bottoms and I am no longer just applying some incremental pressure to force some incremental volume of JB Weld to ooze out at the top, but I just had a strange result with one terminal;

One of my deepest terminals at 5-1/2 turns still felt soft when I hit that point. So I kept gently applying pressure at ~1 minute intervals all the way until an additional 1/8th turn at which point I stopped (even though I felt like I could have threaded further.

Probably I made a mistake when I counted the turns to bottom the grubscrew dry, or a mistake when I noted those number of turns, or I lost track of the number of turns when I began threading with JB Weld.

But the torque required to get the JB Weld to ooze out of the top is not nothing - I believe it would easily pierce a layer of aluminum foil from the pressure/torque involved.

And I’ve seen all the warnings about how important it is to back screws off after bottoming because it is so easy to pierce the thin aluminum bottom of the terminal.

So on the off-chance I’ve ruined thus terminal (or possibly all of the terminals I’ve already JB Welded, what happens when you pierce through the bottom of a terminal and how can you test for it?
 

FilterGuy

What, me worry?
The thing is....Nothing may happen if you pierce the bottom of the terminal. These cells all have a bunch of pouch cells inside. Here is a picture of a plastic case cell:
1613093855014.png

This looks like a Winston cell and they are known to be more robust than others and I am certain that the details of an aluminum case cell is different.... but there will be similarities. In particular, there will be a bunch of pouch cells with tabs that get combined onto the terminal. If piercing the bottom didn't damage one of the pouch cells, the cell will continue to function as normal.

Where things might go off the rails is if for some reason one of the pouch cells goes bad and ruptures. Normally, this would cause the preasure cap on the top of the aluminum cell to burst..... However, if the pressure can escape through the punctured terminal, the pressure cap would not burst so you would have no visual indication of the problem.

If anyone has a cut-away pic of an aluminum cell..... I would love to see it.
 

FilterGuy

What, me worry?
Found this on youtube
Thank you. That is very interesting. I did not expect the liquid in the cell.... If that is normal, the only thing I can think of is that the liquid helps transfer heat to the aluminum case.

The video did not show a good shot of the terminal, but it did not look like the terminals go much deeper than the holes.
 

Dzl

Perpetual Newbie & Unofficial Forum Librarian
Staff member
Moderator
From what I've heard, the terminals on the aluminum commodity cells (excluding Frey/Fortune maybe) are substantially weaker than the terminals on the nylon cased cells (CALB, Winston, Sinopoly, GBS).

Not sure whether or not the liquid (inside the case but outside the pouches) is normal or not. From what I've heard its smelly stuff.

I suspect @Luthj may have some useful input/wisdom (in regards to the original question and/or the liquid)
 

Luthj

Photon Sorcerer
The terminals consist of an aluminum block which is ultrasonically welded to the current collectors (aluminum or copper) foil inside the cells. If you go deep enough on the anode you should see copper from the weld area. On the cathode its aluminum all the way through.

From the video above it should be similar on the larger cells.
1613099619479.png

Some cells use a different fastening method for the current collector foils, but these high density aluminum cased prismatics have limited space.

I have not had an LFP cell apart, but reports are that the electrolyte has a strong chemical odor. Its a clear-ish liquid with low viscosity. If you penetrated the cell, you should be able to invert it and see/smell the liquid.

I have not seen any prismatics with separate pouches. While there are various layouts for the sandwich (rolls, flip flop, etc), they all share a common electrolyte.
 

Maast

Compulsive Tinkerer
Having ruined a few headways by over torquing one of the ends and breaking it loose; there's a organic solvent inside and if you break the seal it'll start leaking and I have to tell you the stuff stinks to high heaven. Also, if you get it on your skin the stink stays there for a long long time.

Turn it upside down and give it a good sniff. If you dont see anything leaking or smell anything you're good.
 

fafrd

Solar Addict
Having ruined a few headways by over torquing one of the ends and breaking it loose; there's a organic solvent inside and if you break the seal it'll start leaking and I have to tell you the stuff stinks to high heaven. Also, if you get it on your skin the stink stays there for a long long time.

Turn it upside down and give it a good sniff. If you dont see anything leaking or smell anything you're good.
Since I glued a grubscrew in with JB Weld, I’m pretty certain I don’t need to worry about anything leaking out...

But thanks.
 

Just John

Photon Sorcerer
Thank you. That is very interesting. I did not expect the liquid in the cell.... If that is normal, the only thing I can think of is that the liquid helps transfer heat to the aluminum case.

The video did not show a good shot of the terminal, but it did not look like the terminals go much deeper than the holes.
I imagine the liquid is the electrolyte.

Per Wikipedia.
 

fafrd

Solar Addict
The terminals consist of an aluminum block which is ultrasonically welded to the current collectors (aluminum or copper) foil inside the cells. If you go deep enough on the anode you should see copper from the weld area. On the cathode its aluminum all the way through.

From the video above it should be similar on the larger cells.
View attachment 36901

Some cells use a different fastening method for the current collector foils, but these high density aluminum cased prismatics have limited space.

I have not had an LFP cell apart, but reports are that the electrolyte has a strong chemical odor. Its a clear-ish liquid with low viscosity. If you penetrated the cell, you should be able to invert it and see/smell the liquid.

I have not seen any prismatics with separate pouches. While there are various layouts for the sandwich (rolls, flip flop, etc), they all share a common electrolyte.
Thanks got the post and the picture.

At most, I penetrated down 1/8th turn it 125microns, so your making me feel much better that I couldn’t have penetrated into the pouch.

And since I had applied JB Weld to the terminal and the grubscrew and it was under pressure (from torque), I’m thinking it must have kept the hole sealed from the get-go and at worst, the small volume of JB Weld I was attempting to force out of the threads through pressure/torque, may have oozed into the cell cavity instead.

I just checked and that’s cell voltage reads exactly the same as it’s brethren that were top-balanced with it and ~1/3rd drained with it in 8S configuration before I started on JB Welding the grubscrews, so I’ll keep my fingers crossed that anything that might have happened to the terminal bottom won’t have any significant impact internal resistance and I may skate through this little episode..,
 

Just John

Photon Sorcerer
Ugggg .... I just had a vivid memory of the Limburger smell. Went to an away basketball game and they snuck on our bus and put limburger cheese in all the bus heaters .... some smell memories never go away.
My best friend, his brother put limburger cheese on his exhaust manifold when he got married. You could smell that car from blocks away.

But, more on topic, I suspect any puncture is well sealed by the JB Weld. I wouldn't worry about it.
 

fafrd

Solar Addict
My best friend, his brother put limburger cheese on his exhaust manifold when he got married. You could smell that car from blocks away.

But, more on topic, I suspect any puncture is well sealed by the JB Weld. I wouldn't worry about it.
That’s what y’all are making me cautiously optimistic about.

I’m hoping that either I barely punctured the bottom but just replaced the aluminum seal with a JB Weld seal or I either undercounted dry turns to bottom or over counted wet turns to bottom with JB Weld (either of which should mean at least 4+ threads engaged meaning stronger than my weakest terminals...

Assuming no leakage, I’m thinking that other that testing internal resistance for a major increase versus other cells, all I can do is see whether capacity of this cell has dropped dramatically..
 

Just John

Photon Sorcerer
If it was electrolyte he poured out of the case in the video, then one or more of the pouches leaked.
Quite possibly, of course he did say it was a bad cell. I just know the contents of the cell in Wikipedia pretty much says the only thing liquid at room temperature is the electrolyte.
 

Luthj

Photon Sorcerer
There aren't pouches inside, just various ways of layering the electrodes.

See this photo, notice how you can see all the foil layers, as well as the separator layers? No mylar pouch material at all.

1613143088364.png
 
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