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I have just torn a part a 2013 nissan leaf pack, the pack has some physical damage and puncture, but only a few module was slightly bend on the corner... Each cell measured 4.03v and they are all within .006v of each other balance wise. Everything seem favorable but my only concerns is when I took apart the 24module (big section)... I understand they're under compression and when taken apart they will expand a bit. However, one side of every single module the aluminum imprint in the middle seem to expand and bulge up a bit... kind of like puffy like RC lithium polymer... I am not sure if that's how they are suppose to be or all of the cells/module are puffy because of misuse?

It's weird, because only one side of each module the aluminum seem to bulge up.. the other side it's still sunk down in the center imprint.

Attached images... am I screwed?
Any advise?
 

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am I screwed?
Any advise?
I've had modules like that and they were fine when reassembled :)

In the past when I was storing Leaf modules I would typically create a pile of ten and use their own weight to minimise 'bulging'. I would rotate the members within the pile once a week so that the top module became the bottom. I did this simply because I found it much easier to assemble packs when the modules weren't bulging.

I would suggest putting them in piles and rotating the members for a couple of weeks and assuming the bulging improves assemble them into your new packs at the correct pressure. As a precaution I would also suggest you keep the modules away from the house and check temperatures on a regular basis just incase something else is going on.

That said 4.03V is ~85% SOC so I think you're ok.
 

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Discussion Starter #4
I've had modules like that and they were fine when reassembled :)

In the past when I was storing Leaf modules I would typically create a pile of ten and use their own weight to minimise 'bulging'. I would rotate the members within the pile once a week so that the top module became the bottom. I did this simply because I found it much easier to assemble packs when the modules weren't bulging.

I would suggest putting them in piles and rotating the members for a couple of weeks and assuming the bulging improves assemble them into your new packs at the correct pressure. As a precaution I would also suggest you keep the modules away from the house and check temperatures on a regular basis just incase something else is going on.

That said 4.03V is ~85% SOC so I think you're ok.

Pheww... that's a relief to know.

So you're saying face the two side that's bulge up against each other? I assumed if I reassembled it back together now without letting it sit and adjust itself would be a super bad idea? Since I would physically push against the cells instantly and do some damage?

Don't quite understand how this could be cause, they seem like they were tie down and secured... can't imaging any physical impact that could have caused this? Unless the cells themselves are puffing?

I was thinking to pull apart the aluminum shell on the damaged corner cells that I will not be using... to see if the lithium cells are puff? good idea?
 

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So you're saying face the two side that's bulge up against each other? I assumed if I reassembled it back together now without letting it sit and adjust itself would be a super bad idea? Since I would physically push against the cells instantly and do some damage?
Once you release the pressure by disassembling the pack all Leaf modules bulge to some extent. Trying to reassemble the pack can be very challenging without minimising the bulging and while we did that on the first pack we built we developed a procedure to use time and weight to minimise the problem on later packs. So, yes place the two bulging sides against one another and build a stack of ten modules... then wait a week and rotate the modules.

I was thinking to pull apart the aluminum shell on the damaged corner cells that I will not be using... to see if the lithium cells are puff? good idea?
Sure, it's easy (see here). Just be extremely cautious about shorting the terminals... I did it once and had molten steel and copper flying around :eek:
 

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Discussion Starter #7
Thank a lot guys.

It's good to have confirmation from previous user... I've use Lithium Polymer for RC stuff for many years... so puffing and bulging lithium are never a good sign. So that's why it freak me out a bit.

I have also pull apart Chevy Volt cells, and didn't notice such bulging, all the cells are pretty much flat.

I guess I will stacked them like Kevin suggested for a week and see what happen. I bought a 30gal flammable cabinet... I think I will stick it in there for now.
 

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Hey guys.

Got some good new, I remove the aluminum shell on one of the damaged module and from what I can tell, the lithium cell is rock firm, no puffing. So I can see it's bulge up in the middle, but this look like it's a deformation of some sort physically.

This got me thinking, wouldn't it be better to leave it the way it is and try to reattached the pack in a way that all of the bulge follow in the same direction? My thinking is it's like a piece of metal, you bend it one way... as long as you leave it like that it doesn't weaken it unless you bend it the other way... ???

Eventually my plan is to hook 6 modules in parallels and make a 14s6p battery for my solar storage application. I look at the relays that came with the Leaf and I want to see if I can use them as a LVD (from inverter to battery) and a HVL (from solar panel to charge controller). This offer extra redundancy in case of a runaway.

At 56volts, 250amp max (my inverter circuit breaker is 250amps). But I dout my system will ever pull this much. I think the most I would ever be pulling is 130amps-150amps. Do you guys think I would need to do the precharge resistor? Or can the relays work without precharge?
 

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Jimmyaz, I disassembled a pack last night. There was also some bulging present throughout my pack but like Kevin, they are stacked to reduce bulging on their own weight. Looks like everyone else has already steered you in the right direction.


Sent from my iPhone using Tapatalk
 

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Discussion Starter #10
Jimmyaz, I disassembled a pack last night. There was also some bulging present throughout my pack but like Kevin, they are stacked to reduce bulging on their own weight. Looks like everyone else has already steered you in the right direction.


Sent from my iPhone using Tapatalk
Thanks for all the reply guys.

One last thing I want to throw it out there... I have exams all of the module closely and I have yet to find a module with any holes or puncture cells. However, I keep on smelling this sweet smell, it's not much... But I know it's there and I can't seem to isolate it to any particular module. I have separated it from the 3 modules that was physically damage... but still the smell is there.

Does any of you ever notice your modules smell sweet? Could it be that yellow rubber that's around the cells giving up that rubber sweet smell? Or is it that puncture lithium sweet smell?
 

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Thanks for all the reply guys.

One last thing I want to throw it out there... I have exams all of the module closely and I have yet to find a module with any holes or puncture cells. However, I keep on smelling this sweet smell, it's not much... But I know it's there and I can't seem to isolate it to any particular module. I have separated it from the 3 modules that was physically damage... but still the smell is there.

Does any of you ever notice your modules smell sweet? Could it be that yellow rubber that's around the cells giving up that rubber sweet smell? Or is it that puncture lithium sweet smell?


I have noticed a similar smell from a couple of leaf packs, I assumed it was the adhesive from the outer casing. This is because when I inspected a few modules that were in the shelf for a few months the smell was not present.

I think you're fine man. As with any pack just closely monitor your pack during test phase. And place your questionable modules in an area that is easy to get to and/or isolate.
 

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Discussion Starter #12
I have noticed a similar smell from a couple of leaf packs, I assumed it was the adhesive from the outer casing. This is because when I inspected a few modules that were in the shelf for a few months the smell was not present.

I think you're fine man. As with any pack just closely monitor your pack during test phase. And place your questionable modules in an area that is easy to get to and/or isolate.
Thanks Danny. That's reassuring. :) Unlike you EV guys I will be using these for my solar storage so it will be inside my Garage... I have the full at most respect for Lithium... I will be placing these pack inside a Flammable Cabinet and add a few redundancy... :)

I think I will only be charging these to 85-90% and discharge down to 40% and leave a head of head room for troubles....

thanks all.
 

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My battery (made up of Fluence modules, same as the Mk1 leaf) builds up that sweet smell in the car if it's been sat for a while (weeks) not used. Once the car is vented for a few minutes it clears. I also noticed the smell quite strongly when I first cracked open the original battery casing from the fluence.

I've also had others report the same smell when opening up both fluence and low mileage salvage leaf packs of the Mk2 module type.

My modules have no damage or any signs of leakage or deteriation at all and still perform perfectly 3 years on... The smell no longer worries me, I think it's actually the smell of electrolyte permeating the materials enclosing the cell somehow. :confused:
 

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Discussion Starter #14
My battery (made up of Fluence modules, same as the Mk1 leaf) builds up that sweet smell in the car if it's been sat for a while (weeks) not used. Once the car is vented for a few minutes it clears. I also noticed the smell quite strongly when I first cracked open the original battery casing from the fluence.

I've also had others report the same smell when opening up both fluence and low mileage salvage leaf packs of the Mk2 module type.

My modules have no damage or any signs of leakage or deteriation at all and still perform perfectly 3 years on... The smell no longer worries me, I think it's actually the smell of electrolyte permeating the materials enclosing the cell somehow. :confused:
I think it's the smell from the yellow silicon rubber that they put around all the cells to protect the edge. Either that or the adhesive they use to glue the side plate on the cells.

Because Chevy Volt is supposedly the same chemistry as the Leaf right? I have open 3 Chevy Volt battery, never notice such smell.
 

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That said 4.03V is ~85% SOC so I think you're ok.
Hi Kevin,

What would roughly be the voltage for 20% SOC? I config my system to a 14s ... But now I just found out my inverter cut off is limited to 48V and it can not be set any higher... Now I may have another problem on my hand... 48v/14s= 3.42volts per cells... Too low?

I would only want to take the battery down to 20%, nothing lower.
 

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...However, I keep on smelling this sweet smell...
The sweet smell is battery electrolyte. My Leaf has that smell when I open battery disconnect hatch behind front seats. I took apart A123 m1A LiFePO4 cell one time, and whole room was filled with strong sweet smell once I unrolled the battery. It must be the electrolyte.

I think pouch cells do vent electrolyte gas through tiny gap between cell tab and plastic pouch.
 

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The sweet smell is battery electrolyte. My Leaf has that smell when I open battery disconnect hatch behind front seats. I took apart A123 m1A LiFePO4 cell one time, and whole room was filled with strong sweet smell once I unrolled the battery. It must be the electrolyte.

I think pouch cells do vent electrolyte gas through tiny gap between cell tab and plastic pouch.

That's odd. Maybe the Leaf cells are different than other?

I have many different type of lithium battery and none have this smell... unless you poke a hole in the cell. :)

Chevy Volt cell, RC lithium polymer, 18650 cell.... None ever had such smell... unless it was poked.

But so far it work... :) Been cycling 5-8kwh a day of the 22kw pack... The voltage hold is amazingggg...
 
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