EVE LF280 arrived damaged.

[Colonel.lp]

My 4 cells arrived today from Xuba, the packaging was fine, but one of the cells has a dent near the top, about 8mm across and 1.5mm deep.(1st picture) What do people think about this in terms of long term functioning of the cell? Should I be adamant about a replacement?

Also is it normal that the sides of the cells undulate, I've never had cells this large before, so was expecting perfectly flat. Across the large sides there is a slight wave(3rd picture), and top to bottom of the large sides they all scallop before the top(2nd picture)

I'd like to know what's what before I chat to Amy.

 

[Steve_S]

The Aluminium on these casings is very thin, pop can thin actually, the large "flat" sides are soft (squeeze the cells) and if you shake them you'll hear some slushing (quite normal). Have a firm grip when you do.

A small crease isn't much to be concerned about if it is at the edge. If it was dented in the middle or crease elsewhere it could be a problem. Check the voltages and if they are close (within 5mv) you 99.99% have nothing to worry about.

 

[AussieSim]

I have 8 cells from Xuba and another 8 from Luyuan, they shipped about 1 month apart.

All of my cells are slightly concave on the short side and all of my cells undulate on the long side. Around half of the cells bulge out (twice, more for the positive terminal than the negative terminal) so much that putting them in parallel to top balance with the supplied busbars means the cells putting tension on the terminal grub screws and splaying apart at the base.

Because the positive terminal bulge is larger than the negative terminal bulge, and the degree varies, I can make 8s square packs with each set of 8 that fits without tension on the terminals.

 

[Colonel.lp]

I have 8 cells from Xuba and another 8 from Luyuan, they shipped about 1 month apart.

All of my cells are slightly concave on the short side and all of my cells undulate on the long side. Around half of the cells bulge out (twice, more for the positive terminal than the negative terminal) so much that putting them in parallel to top balance with the supplied busbars means the cells putting tension on the terminal grub screws and splaying apart at the base.

Because the positive terminal bulge is larger than the negative terminal bulge, and the degree varies, I can make 8s square packs with each set of 8 that fits without tension on the terminals.

View attachment 26104View attachment 26105View attachment 26106

That's the same as mine too, I did also notice the difference at the +and- after I posted. Luckily I'm just making a 4s so it will even out. I'm going to clamp mine with 10mm aluminium plates at each end and 4mm between the cells, so will be interesting to see how they clamp, and if charge cycles will cause expansion in the gaps. I am a bit miffed a about the dent though, that should have been picked up when packing.

 

[snoobler]

Concerning the case inconsistencies, if they can be easily squeezed flat to one another, I wouldn't be concerned. HOWEVER, on the dimple, that's an indication of a significant impact. The location isn't that much of a concern, but that something like that could happen to it indicates a lack of production/quality control. Personally, I would ask for a replacement for that one.

 

[Colonel.lp]

Thanks, that's what I was thinking really, considering they are supposedly matching the cells, it would have been obvious.

 

[Gazoo]

All of my cells are slightly concave on the short side and all of my cells undulate on the long side. Around half of the cells bulge out (twice, more for the positive terminal than the negative terminal) so much that putting them in parallel to top balance with the supplied busbars means the cells putting tension on the terminal grub screws and splaying apart at the base.

Mine are the same and came from Basen. My busbars reach but barely. We know some expansion is normal and I wonder if the expansion is on account of capacity testing done by the supplier. I haven't tried to flatten them out. Does anyone know if they will flatten out when compressed?

 

[Steve_S]

A few simple suggestions.
Seriously do consider binding / squeezing / compressing the cells when making your battery packs. It does not have to be heavy duty pressure but enough to say a "double hand squeeze" on clamps, then bind the cells together. Box them, use plates, etc, to keep them that way.

On "plates" if you are using the threaded rod with end plates method... Use Wood, Acrylic, ABS and even aluminium BUT BE CAUTIOUS !
- tip, if making end plates, consider cutting "handles" into the material at the tops, makes handling the packs so much easier.
- The threaded Rods should be covered with a non-metallic tubing,
- The face of the metal which will be touching the cels should have a Non-metallic insulator between the metal & cell.
- DO NOT FORGET Bottom Support ! (Imagine picking the whole kit up and having the cells fall out the bottom ~bad day~)

Just like the tools you use when assembling your battery packs, and taping off wrenches, sockets etc to prevent an accidental short because you can get Really Zapped ! Making sure that none of the materials used in your casing could cause a short, whether immediate or over time due to chafing or rubbing from motion or vibrations (if mobile).

I have squeezed all of my cells, bound them and boxed them tightly in cases I made myself,
The cells all flattened out without much effort. BUT my method was to square them up, squeeze them, let them sit for a couple of hours, then again a wee squeeze, then another hour, and bind them.

Below is a series of Pics:
Squeezing the recovered cells from that ShunBin Disaster (forgot to take photo's when I did my 280's)
They are wider cells compared to 280's so binding a bit different.
280AH Square Pack Box pre-assembly & assembled.
280AH Box with cells installed. Also shown are the 280AH cells bundled into sets of 4 (pull string there to help removal from box if needed)

 

[Deleted member 9967]

Mine bulged out in the middle a tiny bit.
But I expected that.
The dent is another matter that I will not address as others already have done so.

 

[Gazoo]

I'm going to clamp mine with 10mm aluminium plates at each end and 4mm between the cells,

The reason for clamping is to increase the number of cycles from 2000 to 3500. If you have 4mm between the cells your are defeating the purpose of clamping them.

 

[Gazoo]

Because the positive terminal bulge is larger than the negative terminal bulge, and the degree varies, I can make 8s square packs with each set of 8 that fits without tension on the terminals.

After taking a closer look at my cells there are two out of 8 cells like yours. I completed my top balancing and those two did not appear to expand any more. The other cells did expand slightly. Fortunately by arranging them I was able to make a square pack.

I am planning on mounting the BMS over the weekend and will begin a capacity test.

 

[Colonel.lp]

Ok. Update guys.
As you know I mentioned in another thread that all my cells had arrived 99% charged.

After top balancing to 3.65V and 0 current draw, I let them sit for 12hrs before test. They all settled to 3.332, 3.339, 3.331, 3.325 ∆14mv not too shabby.

I did a capacity test on the pack with the BMS set to Cutoff at 2.5, and right down until the bottom the cells impressively stayed within ∆14mv right until the bottom when one cell dropped much faster. Pack capacity was 262ah with cells settling back to 3.169, 2.868, 3.156, 3.155 a few hours after cufoff. ∆300mv ! Draw was 0.05C

Charged back up to 3.65V again, about 30 minutes into a 0.17C (50amp) charge, the cells were back to a ∆14 and pretty much stayed that way until charged.

2nd capacity test on offending cell, at 0.07C discharge, result is 265ah. (Load tester cutoff voltage adjusted to account for voltage drop)

Manufacturing date: 89/9/06

One bad cell. Next one is on the bench.

@smoothJoey @ArthurEld @Gazoo

 

[John Frum]

Charged back up to 3.65V again, about 30 minutes into a 0.17C (50amp) charge, the cells were back to a ∆14 and pretty much stayed that way until charged.

Sounds like a good top balanced pack with a weak cell.

 

[ArthurEld]

Ok. Update guys.
As you know I mentioned in another thread that all my cells had arrived 99% charged.

After top balancing to 3.65V and 0 current draw, I let them sit for 12hrs before test. They all settled to 3.332, 3.339, 3.331, 3.325 ∆14mv not too shabby.

I did a capacity test on the pack with the BMS set to Cutoff at 2.5, and right down until the bottom the cells impressively stayed within ∆14mv right until the bottom when one cell dropped much faster. Pack capacity was 262ah with cells settling back to 3.169, 2.868, 3.156, 3.155 a few hours after cufoff. ∆300mv ! Draw was 0.05C

Charged back up to 3.65V again, about 30 minutes into a 0.17C (50amp) charge, the cells were back to a ∆14 and pretty much stayed that way until charged.

2nd capacity test on offending cell, at 0.07C discharge, result is 265ah. (Load tester cutoff voltage adjusted to account for voltage drop)

Manufacturing date: 89/9/06

One bad cell. Next one is on the bench.

@smoothJoey @ArthurEld @Gazoo

Thanks for sharing your results Colonel.lp
So far I have not been able to figure out why one of my cells hit the high limit before the rest.
I don't think capacity is the issue with mine.
My internal resistance tester is supposed to be here by Monday. Maybe I can get some useful info with that.

 

[Colonel.lp]

Thanks for sharing your results Colonel.lp
So far I have not been able to figure out why one of my cells hit the high limit before the rest.
I don't think capacity is the issue with mine.
My internal resistance tester is supposed to be here by Monday. Maybe I can get some useful info with that.

From my limited experience of these cells, and recharging the balanced pack, the rise from about 3.5ish up to 3.65 is really rapid. It was like the 4 cells were having a sprint to the finish line. Interestingly the low capacity cell wasn't the one that was misbehaving with rapid rise before. It still worries me that looking at the manufacturing dates they have potentially been sat at near 100% for 2 years. Waiting with interest to see the second cells capacity. Not sure what is acceptable tolerance.

 

[Luthj]

New cells should meet their nominal capacity at a minimum, in this case 280AH. That being said, as long as you are happy with the value, you can safely operate the pack even with one cell that's 10% less than the best cell. It just means your total pack capacity is limited by the weakest cell.

 

[Colonel.lp]

New cells should meet their nominal capacity at a minimum, in this case 280AH. That being said, as long as you are happy with the value, you can safely operate the pack even with one cell that's 10% less than the best cell. It just means your total pack capacity is limited by the weakest cell.

I ln my case I wouldn't really be happy with anything other than a few amp hours below stated capacity, certainly far from happy with 265ah. I live in my motorhome, and every ah is critical in the winter while solar is negligible.

 

[Gazoo]

After top balancing to 3.65V and 0 current draw, I let them sit for 12hrs before test. They all settled to 3.332, 3.339, 3.331, 3.325 ∆14mv not too shabby.

My 8 cells are all resting between 3.58 and 3.580 and they finished top balancing at 1-5-2020 1:10AM. I don't know how long it takes these cells to get to their resting voltage but that's what I see with mine.

 

[Colonel.lp]

My 8 cells are all resting between 3.58 and 3.580 and they finished top balancing at 1-5-2020 1:10AM. I don't know how long it takes these cells to get to their resting voltage but that's what I see with mine.

So you are saying after 48hrs resting they are all at 3.58? Is that what they should be?

 

[ghostwriter66]

The reason for clamping is to increase the number of cycles from 2000 to 3500.

OK - i had to delete my first response(s)(s) -- deep breath -- WHAT ARE YOU BASING THIS ON???