Can you de-bloat XUBA 280aH Lifepo4 cell?

For the OP. You might check ebay. I am seeing a few sellers with 280AH cells. They aren't cheap, but it might be better than air shipping on a single cell. You could also contact the sellers to see if they have individual cells. You could also post up to see if anyone is putting an order in for cells, and have them add 1 more.

Ampster said:

If i understand the differences between active and passive it is that active balancing uses less power because it transfers energy between cells. That would be from high voltage to low voltage near the top and bottom.

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Yes, exactly

Ampster said:

If i understand the differences between active and passive it is that active balancing uses less power because it transfers energy between cells. That would be from high voltage to low voltage near the top and bottom.

Click to expand...

It has also been my casual/passive observation that active balancers tend to have a higher balance current. But I don't know if this is broadly true or just what I've noticed.

It seems most passive balancing BMS are between 35 mA and 150 mA, (Chargery being an exception to this), whereas the active balancer's I've seen are capable of like 1-3 A. This may or may not be representative, but has been my observation based on most common BMS and balancers used on this forum.

Dzl said:

It has also been my casual/passive observation that active balancers tend to have a higher balance current. But I don't know if this is broadly true or just what I've noticed.

It seems most passive balancing BMS are between 35 mA and 150 mA, (Chargery being an exception to this), whereas the active balancer's I've seen are capable of like 1-3 A. This may or may not be representative, but has been my observation based on most common BMS and balancers used on this forum.

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I have seen the same thing as you ......... and also like you not an expert or professional on this subject, .....and would agree with the "most of the times for most of these things" generality....... the passive ones I have seen are resistive load dumps so they generate heat ......... and for 3 Amp balance current it would have a rather large heat sink getting adjacent components hot. Plus most folks with limited PV power, or large power bank owners where all this little energy adds up to large energy ...... would not want so much wasted power. Value added for cost of design/manufacture makes capitalist/free market sense for larger balance amp design complexity-probably not so if really low balance amps on mass produced consumer applications where such minor wasted power hardly drives consumer purchase dollars as much as value (cheapness).

fhorst said:

I stand corrected for the naming confusion

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So we agree Lithium or Lithium Ion should be used as a general term for batteries using lithium in their chemistry? Many of us might eat fruit, but only a few eat Mango or Pear.

Ampster said:

So we agree Lithium or Lithium Ion should be used as a general term for batteries using lithium in their chemistry? Many of us might eat fruit, but only a few eat Mango or Pear.

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Not sure.. I guess we do

If we talk about normal day to day used lithium battery, that are mostly Lithium Polymer, and say that the general term for Lithium Polymer is "Lithium" or "Lithium ion", yes.
Totally

If you like to include lifepo4 and other new chemistry types, I disagree.

General speaking lithium ion (polymer) is "everywhere" and dangerous if used wrong.
Many people fear their possibly to catch fire or explode, and they should.

That fear is not justified for Lifepo4.
It is the "safe" type.

I can not speak for all bloated cells.
I can talk about my experience with my bloated cell, that shows almost no capacity difference with a "good" cell.
150 Vs 152Ah.

I didn't do capacity test on all my cells but expect that several others who aren't bloated will give 150Ah as well.

For day to day usage, nothing wrong with mildly bloating cells.
My personal experience and research showed this.

Extreme bloating for sure is a problem

Even then, continue to use them will be still safe.
Those cells probably have just 1/4 or less capacity left and drop fast in voltage
That makes them useless to use, not dangerous.

One bad cell in a serie will reduce the overall capacity, not make it dangerous or leak power from the good to the bad cell.
Most likely, your BMS will go crazy due the low voltage on one cell ?

Lithium or Lithium Ion that most people talk about is Lithium Polymer.
For that type of Lithium Ion cell, using a highly bloated cell is dangerous.

Other types, it's not.
Maybe useless, not dangerous.

fhorst said:

If you like to include lifepo4 and other new chemistry types, I disagree.

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Three people have told you that LFP or LiFePO4 is just one of the types of Lithium batteries. Why do you insist on your own definition?
Using your analogy you are saying pears are not fruits.
I know English is not your primary language but you did indicate that you attended a US university so I know you must understand logic. What logical argument can you make for using unconventional terminology?

fhorst said:

Lithium or Lithium Ion that most people talk about is Lithium Polymer.

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If you are a radio control hobbies there is a lot of Lithium Polymer battery use. If you are an EV builder or manufacturer the Lithium ion type most commonly used is NMC or other Lithium Iron chemistry containing Cobalt.

I never attended any US university, you must me mistaken me for some one else.
Or any university for that matter.
I have several computer related papers, like MCSE, master CNE, some Cisco related, DBA (SAP, Oracle), list goes on for a while.
Sadly last time I used any of them professionally was 15 years ago, before the problems in the hospital.
Since then I've been on high doses of pain meds, morphine related and grown from not being able to read a page of Donald duck (concentration problems) to where I am now.

Not as sharp as I used to be, flying around Europe, fixing computer related problems at the top 500 companies, but I'll get by. It was a long struggle.

The basics stay the same.
Is slightly bloated lifepo4 safe or unsafe.
That is the question here, and the part where the disagreement is.
I totally agree that slightly bloated lithium polymer is unsafe.

Lifepo4 is one of the (safe) lithium battery.
Yet, some people insists that lifepo4 is as dangerous as lithium polymer once bloated.
Saying it is the same.
I clearly disagree on that point.

Lifepo4 (pear) is the safe type
Lithium polymer (apple) is not.

When a cell gets bloated, looking more round, it suddenly is as dangerous as lithium polymer (apple)

Yes apples are more round then ?, that doesn't make them the same dangerous.

Does it?
Two of the three insist that it is.

Talking about dangerous thermal run away, and electrical fire.

I clearly disagree on that point of few.
Thermal run away that can occur when 2 sheets make contact is problematic for lithium polymer, not for Lifepo4!

You can puncture with an iron pin the whole pack, making connections between many sheets, without any real problems.
I would not advise to keep using a punctured or shot at cell, that is clear also.

The advice to stop using a cell because it's slightly bloated as it "is dangerous" is plain wrong, based of the fear from lithium polymer.

It is fine they like to stay away from the edge of the world, as according to them it's still flat
Sure.

They just should not advise people to stop using slightly bloated cells with the doomsday scenario that it will burn their house down.

With any Powerwall that is a possibility, it won't be the fault of the bloated lifepo4 cell

I know it's hard for them to accept that lifepo4 is not as dangerous as lithium polymer.

Alarm bells going off for lithium polymer are not intended for Lifepo4.

Like it was hard for people to accept that our world isn't flat..

That's is fine for them, don't use slightly bloated lifepo4 cells

Please just don't spread useless fear that will cost other people their money.

So now we agree that Lithium battery terminology contains many subsets, including Lipo and LFP. I think we have always agreed that Lipo is not safe.
Thanks for the insight into your thought process. Best of luck.

The only disagreement is about (slightly) bloated lifepo4 cells being safe to use, or not.

Abused cells naturally never are safe to used.

Lifepo4 Cells that have some bloating during normal operation, are perfectly safe to use.

Telling people that they suddenly are as dangerous as bloated lithium polymer is plain wrong advice based on fear.

I have used slightly bloated used LFP cells safely on the past. If they became bloated under the user's watch then before using them the user should have a clear understanding of how they became bloated.
In my case it was over discharge and most of them came back to at least 95% capacity but remained bloated.

Ampster said:

In my case it was over discharge and most of them came back to at least 95% capacity but remained bloated.

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I should add that the process of restoring an over discharged cell or cells needs to be done carefully with attention to current. It is not as simple as putting a load on an overcharged cell.

It seems that just as the LiFepo4 hold same voltage while discharging and then drops fast at end, the charge does same and when a cell reaches 3.65 it charges alot faster and reaches high voltage quickly before other cells have reached 3.65, BMS supposed to cut charge when individual cell reaches a certain level. Not cumulative V but individual cell V is the thing.

jonnyo said:

thank you for sharing your experience as it s a frustrating situation but it s worth a lot to other like me to learn. I put my set of 4 battery in the solar system and will let the BMS do the work over the next few weeks. Seems like they are getting closer and closer daily. But i think my impression of this is... a BMS is essential and such a peace of mind.

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Verify the BMS HIGH/LOW cell V disconnect, some don't even work, don't believe "SPECS" until you see it work.

most lipoly cell will bloat soon or later, it is very common on laptop, it happens on smartphones and tablets.
Lipoly is made to bloat. It doe not make it dangerous, but yes, unsafe is the word.
i would be more worried by li-ion that are prone to set on fire without warning (like in e-cigarettes).
I think LFP is pretty comparable with Lipoly, except most LFP are hard cased, so bloating will be hidden
for most of the cases.
for the problem with prismatic LFP at high capacity as the XUBA 280Ah , i think it is just a normal issue.
People think that industrial processes deliver standard and identical products.
that is not the case most of the time.
it cost less to produce loose specs and make bin sorting at the end than trying to stick to hard specs and reject the bad ones.
at least if you are targeting mass production and cheap price.
so i think if you want premium cells, you will purchase the same as XUBA is selling, but you will have a warranty about
performance.
you can also purchase more cells than needed (16 instead 8) , and if you are lucky you get twice the capacity.
if not you could possibly sort the cells to produce 2 batteries with matched cells.
You can also override problem with some BMS or balancer.
if very unlucky, you will end up with some "defective" cells and try to return them, but since cost of shipping largely exceed the value of
the product, it is easier to trash them.
even purchasing double bring you still lower price than an equivalent tesla wall.
So i would say there is no XUBA quality, XUBA seems to be only a box pusher.
The only service they provide is to sell and ship you cheap cells, and apparently they do this right.

binning cells is a tedious task, you have to draw the charge/discharge curve for each cell.
at then end you can set the low limit for the weakest cell and the high limit for the strongest cell, so all cells are happy.
example , you stop discharging when first cell reach 3V and you stop charging when first cell reach 3.5V.

My 32 x 280Ah cells, none of them are bloated yet. (16 not yet installed)
From the 48x 152Ah... sadly several are bloated.
I don't know exactly how much till next week when i'll be doing serious maintenance.

I tried to make my own busbars from old copper I have left over.
That didn't workout.
Now I ordered 22.5 kg copper bars, when they arrive, time to make permanent setup.

I did search to find replacements for bloated 152's, only to find that production was stopped for the 170x173x45mm 152Ah
Reason: They bloat..
The 170x173x45mm casing used fro 100Ah to 152Ah. Till 130Ah it went fine, higher.. not.
The 140Ah and +150Ah all have problems. Not all the cells, but significant part of them.
The +150Ah for sale now have a bigger casing.

Statement:
Probably all cells are expanding / bloating but their casing is big enough so most of the times you don't see it.

Other statement:
Its good practice to compress cells, tape them together (@Will Prowse like to do) use large "hose clamps" or other ways to make compact set.

This brings me to an interesting question:
As the 152Ah cells (those I know for sure) have "too small casing", and will expand / bloat beyond the limitations of the casing....
Should those be compressed?? Or better give them the space the need??

I can see 3 options:

1. The elastic tape used by Will can give the best of both worlds, but then flexible bus-bars should be used. (braided) (@BiduleOhm, thanks for this tip!)
2. Or, when using rigid bus-bars, keeping the cells somewhat apart to give them the space they need to expand
3. Or compress the new cells in a way they can't expand. Not sure what would happen! (I can think of nasty scenario's)

What would be best and why?

I choose nr2.
My setup 1016Ah / 50 kwh will handle 275-300A loads, that does require thicker bus-bars.
Massive was already a pain to find in Thailand, braided in that size..... not available.

That rules out option 1.
Option 3..... I don't want to risk my +$5.500,- investment just to keep them look nice.

I am really curious about the results if compression will be done at the start.
Compressing already slightly bloated cells seem like a really bad idea to me.

JoeHam said:

That is why I chose to never top balance my new, well matched cells and have been a proponent of that policy on the forum.

Here is how I made my choice:

I tend to make decisions based on a risk/reward analysis. The supposed benefit of top balancing is increased capacity, or increased cell life or ? To be honest I'm not sure what the benefit is.

However, for the sake of discussion, let's assume that top balancing gives us a 10% increase in some measurable parameter for a cell.

We have seen reported, more than once, irreparable cell damage during the top balance exercise. When this does happen, AFAIK this has always resulted in a 100% loss of the cell.

So I have a 100% risk to the cell for maybe a 10% benefit? That would be a 10X risk/reward. I would prefer to see a risk/reward of less than a whole number.

Just my opinion.

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When I got mine, they were all the same voltage. Hooked them all up parallel, hit them with a 15 amp power supply, and was surprised that within minutes they were going over voltage. They were already stuffed and over 14.8 or something like that. Sucked them back down quick, built the battery, fine ever since.
I’m with you, all this step charging top balance was unnecessary.

fhorst said:

My 32 x 280Ah cells, none of them are bloated yet. (16 not yet installed)
From the 48x 152Ah... sadly several are bloated.
I don't know exactly how much till next week when i'll be doing serious maintenance.

Other statement:
Its good practice to compress cells, tape them together (@Will Prowse like to do) use large "hose clamps" or other ways to make compact set.

This brings me to an interesting question:
As the 152Ah cells (those I know for sure) have "too small casing", and will expand / bloat beyond the limitations of the casing....
Should those be compressed?? Or better give them the space the need??

I can see 3 options:

1. The elastic tape used by Will can give the best of both worlds, but then flexible bus-bars should be used. (braided) (@BiduleOhm, thanks for this tip!)
2. Or, when using rigid bus-bars, keeping the cells somewhat apart to give them the space they need to expand
3. Or compress the new cells in a way they can't expand. Not sure what would happen! (I can think of nasty scenario's)

What would be best and why?

Click to expand...

For option 2 : I see a vendor on Alibaba has a plastic stack frame for prismatic cells which will give some rigidity and some space between cells.

I choose option 3 : Like Will, I'm going to wrap with tape and large hose clamps (+/- double sided tape in between cells)

By my calculations 8s * 280Ah cells in a 2 rows of 4 has a circumference of 1266.4mm

The only large enough hose clamp I've found online is to join 2 * 700mm hose clamps.


This should still leave enough space to put option wooden/acrylic plates at either end.

AussieSim said:

For option 2 : I see a vendor on Alibaba has a plastic stack frame for prismatic cells which will give some rigidity and some space between cells.

I choose option 3 : Like Will, I'm going to wrap with tape and large hose clamps (+/- double sided tape in between cells)

By my calculations 8s * 280Ah cells in a 2 rows of 4 has a circumference of 1266.4mm
The only large enough hose clamp I've found online is to join 2 * 700mm hose clamps.

This should still leave enough space to put option wooden/acrylic plates at either end.

Click to expand...

CALB cells like you show have rigid casing and probably wouldn't visually bloat.
For the CALB type, yes, totally agree.

CALB with rigid case:


Eve cells with aluminium case:


unknown brand, also aluminium casing:


If you know you have cells that will expand / bloat, would you still choose to clamp them together?
And why?

In my situation the cells are standing on 20cm thick reinforced concrete, they should not move.
(if it does, the cells are the least of my problems )
Adding a plastic stack frame doesn't add any benefit, except cost.
If it would be cells in RV or other mobile application, they can be a good help!
Can you share the link for those who need it?