Leaking Electrolyte from Bigbattery Powerblock

Will Prowse

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Just my luck as always. I contacted poison control and they think I will be fine. No symptoms so far.

I am pretty sure it is due to cell configuration. 92 pounds of cells stacked in this manner does not seem like a good idea. Second to bottom cell has gas inside and you can hear the electrolyte sloshing around.

I would love to hear your thoughts.
 

Sillyputty

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Wow - that sucks. Did any of the cells vent through the top-vent? [Edit - to add screen-grab of sloshing cell]

1613586962568.png
 
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snoobler

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Just my luck as always. I contacted poison control and they think I will be fine. No symptoms so far.

I am pretty sure it is due to cell configuration. 92 pounds of cells stacked in this manner does not seem like a good idea. Second to bottom cell has gas inside and you can hear the electrolyte sloshing around.

I would love to hear your thoughts.

It looks to me that they at least attempted to address weight via the shelf such that the bottom cell only supports the weight of 3 cells above.

Preponderance of the evidence suggests cell defect over design flaw UNLESS they are not designed to operate on their side as you indicated and/or they should not be stacked that high.
 

curiouscarbon

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i’m glad you’re ok no symptoms

structural integrity of pack with >100Ah cells seems to become increasingly important

thank you for sharing this case
 

alfaeric

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I'm interested to find how where to find the battery specs on what kind of physical loading the shells can take.... I was considering a BB pack for my trailer, as well as a DIY 36V pack in the future.

Even if they are upright, how much loading can they take? As in- should one put a mat between the battery pack and hard surfaces? For instance, if you could put the entire pack in a milk crate (as Will's examples have), should you put some cushion between it and whatever trailer frame it ends up sitting on?

While it would be easy to blame Big Battery, the more interesting path I hope this goes is actual physical capabilities of the batteries.
 

Gazoo

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Second to bottom cell has gas inside and you can hear the electrolyte sloshing around.
Many of us who have EVE cells can hear electrolyte sloshing around in the cells. I am not sure that means anything. I would like to know what bigbattery thinks about this.

EVE has said stacking cells on the side is ok but they did not indicate the number of cells. I would like to know what bigbattery has to say about that as well. But they do have a plate between the cells and I would think stacking 4 on top of each other would not cause the cell to leak.

Electrolyte leaking is odd. Hopefully we will be told what caused it.

Glad you are ok. :)
 

Gazoo

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Even if they are upright, how much loading can they take? As in- should one put a mat between the battery pack and hard surfaces? For instance, if you could put the entire pack in a milk crate (as Will's examples have), should you put some cushion between it and whatever trailer frame it ends up sitting on?
There is no problem if the cells are kept upright and mounted in a fixture. What one needs to look at is the load capacity of the case if carrying the cells around. If cells are going to be stationary this is not as much of a concern. However in both cases it's a good idea to put plywood in the bottom of the case including milk crates and I also think it's a good idea to put an insulator between the cells especially if used in a mobile environment.
 

Luthj

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The electrolyte (Dimethyl carbonate) is essentially no more dangerous than methanol, and will eventually metabolize even if directly ingested in small amounts. The lithium perchlorate dissolved in the electrolyte is not fun on skin, so thorough washing is suggested. I wouldn't breathe the vapor for an extended period. Note that it is quite flammable, and static discharge could ignite it under the right circumstances.

In a well ventilated or outdoor space there isn't much concern.

EDIT: looks like some other stuff is in the electrolyte, see my post below. Avoid contact with the skin, use good ventilation.
 
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SteveDashH

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The electrolyte (Dimethyl carbonate) is essentially no more dangerous than methanol, and will eventually metabolize even if directly ingested in small amounts. The lithium perchlorate dissolved in the electrolyte is not fun on skin, so thorough washing is suggested. I wouldn't breathe the vapor for an extended period. Note that it is quite flammable, and static discharge could ignite it under the right circumstances.

In a well ventilated or outdoor space there isn't much concern.
Thank you for the feedback, the toxicity of the electrolyte in these cells has been a concern of mines. Someone asked this question under the video, but no answer yet, what smell should we be looking out for? I've read other places that the smell of the electrolyte is sweet and fruity.
 

Will Prowse

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The electrolyte (Dimethyl carbonate) is essentially no more dangerous than methanol, and will eventually metabolize even if directly ingested in small amounts. The lithium perchlorate dissolved in the electrolyte is not fun on skin, so thorough washing is suggested. I wouldn't breathe the vapor for an extended period. Note that it is quite flammable, and static discharge could ignite it under the right circumstances.

In a well ventilated or outdoor space there isn't much concern.
Good to know. What about the warnings stating that contact with water would create hydrogen fluoride? That stuff seems super dangerous. What is causing that reaction?

I really have no clue how to clean this stuff up. It is soaked into the floor board of my trailer. Any advice would be extremely appreciated.
 

Luthj

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Good to know. What about the warnings stating that contact with water would create hydrogen fluoride? That stuff seems super dangerous. What is causing that reaction?

I pulled a couple SDS, and it appears most LFP cells these days are using cells are using Lithium hexafluorophosphate as one of the components of the electrolyte. I can't tell if its by total weight or liquid percentage. Cells can also use LiBOB (Lithium bisoxalatoborate) or LiBF4 (lithium tetrafluoroborate) instead though, so reading the SDS is suggested.

1613608249788.png

LiPF6 will react with water to produce HF, LiF and phosphoric acid. Hence why you should wash any electrolyte off your skin, and work in a well ventilated area. There may be better solvents for washing skin than water, but I would need to consult a chemist, pure alcohols may work fine.

Atmospheric moisture will react, but its a pretty slow process. The carbonate evaporates readily, shielding the LIPF6. HF gas is much heavier than air.

The real risk is prolonged skin exposure, as water in the skin can react over time and HF can be absorbed. I guess if you took a nap in the room with a bunch of electrolyte that could be a problem.

Some back of the envelope math indicates high toxicity would require direct exposure to more than 1 cells worth of electrolyte.

The stuff is nasty, but its not an brief exposure risk. Use gloves, wash any exposed skin, use good ventilation.

If you have some soaked into the floor or other materials, ventilate the area before entering and during occupation for a week or so.
 
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Luthj

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Assuming the cells have 1 cup (about 30 grams) of electrolyte.

If its 4% of the liquid volume, then the breakdown is as follows:
4% is 1.2 grams of LiPF6
35% of that is F so 0.42 grams
100% conversion would yield ~0.5g of HF.

Exposure limits are 2.5mg per cubic meter in the air.

500mg/2.5 = 200 cubic meters of air to dilute.

Of course this assumes a bunch of stuff.

If its 4% of total cell weight, then the total amount in the cell is probably 50x higher. Though most of it is locked into the separator.
 

Will Prowse

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Thank you Luthj. I appreciate your insight. I was mostly concerned with the gas, but considering how slow this process seems to happen with atmospheric moisture, and that it was well ventilated, and the gas is heavy, I think my lungs should be alright.

This is a great lesson for everyone about the dangers of the electrolyte used. I will exercise more caution now and mention these points in the videos.
 

snoobler

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It also happens with the copious amount of water vapor in your lungs, so if you can't smell it, you're good. If you smell it and it burns your eyes, sinuses, chest.. GTFO...
 

Hedges

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Good to know. What about the warnings stating that contact with water would create hydrogen fluoride? That stuff seems super dangerous. What is causing that reaction?

I really have no clue how to clean this stuff up. It is soaked into the floor board of my trailer. Any advice would be extremely appreciated.


Couple of SDS



For Lithium hexafluorophosphate, do not add water.
For HF, treatment involves calcium compounds.

Seems to me slathering a calcium compound over the soaked floorboards might be a good idea. But not one made up with water?
Maybe place a tape layer over that area, to hold the compound and minimize gasses entering room?

I'm an electrical guy, pretty weak in chemistry.
 

Picasso

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I would have thought the cells would have had some sheet as a separator. Shipping those like that could cause them to rub to the cell case. Also no banding...
 

DerpsyDoodler

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I would have thought the cells would have had some sheet as a separator. Shipping those like that could cause them to rub to the cell case. Also no banding...
IIRC I am almost certain I read somewhere or saw on a video that prismatic cells should be installed upright. I have no reference, just a nagging familiarity. I’ve watched too many videos and read too many papers to keep track. Would not have opted to design a sideways installation myself, though I understand what enticed BB to do it.
 
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