280a LifePO4 Battery

[SeanF1]

I see that Fogstar offer tested and matched Grade B Eve 280ah cells for £119.99. 12 month warranty. Has anyone built a battery pack using these and how are they performing?
Cheers,
Sean

 

[Raul]

I have no idea about the B grade. I did seen a review left from buyer of B grade, stating they are as expected 10% down on capacity. My opinion is if you build a bank and don’t expect to pull big rates, they are worth it. But, if you expect to pull 0.3Cand above, better to go for the grade A. The grade A double terminal it’s miles better compared to the single stud found on grade B.

 

[SeanF1]

I have no idea about the B grade. I did seen a review left from buyer of B grade, stating they are as expected 10% down on capacity. My opinion is if you build a bank and don’t expect to pull big rates, they are worth it. But, if you expect to pull 0.3Cand above, better to go for the grade A. The grade A double terminal it’s miles better compared to the single stud found on grade B.

They say that they guarantee that the capacity will be at least 277ah.

 

[Lenny HB]

You are only going to save £100 on the 4 you need for a 12v battery so is it worth the risk?

 

[Raul]

They say that they guarantee that the capacity will be at least 277ah.

There abouts, not bad for the price, looks good value.

I don’t think it’s any risk Lenny, if they match them from the same batch, and have equal or close resistance, and no bulges, then they as good as new 277ah cells. These cells are not cycled at all, they are just graded by manufacturer at first test, then the seller can grade them again if he/she wishes to weed out the week ones.

^{_{Subscribers  do not see these advertisements}}

 

[SeanF1]

There abouts, not bad for the price, looks good value.

I don’t think it’s any risk Lenny, if they match them from the same batch, and have equal or close resistance, and no bulges, then they as good as new 277ah cells. These cells are not cycled at all, they are just graded by manufacturer at first test, then the seller can grade them again if he/she wishes to weed out the week ones.

This was my thinking on risk also. Probably a lot less risky than buying so called Grade A cells from AliBaba. I've discussed with a lot of AB suppliers over the last few days and 4 x 280ah Eve LF280Ks are costing in the region of $540 to $560 delivered direct duty paid to the UK. This is £450 - £460 and of course you are not sure whether what is going to turn up will really be Grade A anyway. So these matched and guaranteed Grade B for £479 (free delivery) for 4 compare well

 

[Raul]

I share your concern with alibaba, if they can’t provide factory data sheet with your cells QR, then I would not touch them.

 

[Ditcha]

This was my thinking on risk also. Probably a lot less risky than buying so called Grade A cells from AliBaba. I've discussed with a lot of AB suppliers over the last few days and 4 x 280ah Eve LF280Ks are costing in the region of $540 to $560 delivered direct duty paid to the UK. This is £450 - £460 and of course you are not sure whether what is going to turn up will really be Grade A anyway. So these matched and guaranteed Grade B for £479 (free delivery) for 4 compare well

How do you know the grade B cells are actually what they say if the grade A aren't?
It's a bit of a minefield to be honest you just need to do your homework and stick with good feedback and recommendations and keep your fingers crossed good luck but I would go for A grade and if they were B grade it wouldn't really bother me at that price.

 

[SeanF1]

How do you know the grade B cells are actually what they say if the grade A aren't?
It's a bit of a minefield to be honest you just need to do your homework and stick with good feedback and recommendations and keep your fingers crossed good luck but I would go for A grade and if they were B grade it wouldn't really bother me at that price.

Only because Fogstar is a reputable UK company who purchase direct from Eve and guarantee that the cells are what they say and they test, match, and give a 12 month UK warranty.

 

[DavidCh]

I worried about this so much when I bought my cells on Alibaba. Having now learnt a lot more, I think its probable I (we) worry too much. From my perspective if my 280ah bank was only actually 270 it would not make any real difference and (as other people have pointed out as well) if it only did 1000 cycles, not 3000 its still going to last much longer than I am.

^{_{Subscribers  do not see these advertisements}}

 

[Ditcha]

Interesting comparison on grade of cells here.

 

[SeanF1]

Interesting comparison on grade of cells here.

This is a very interesting video.
Forgive me if I am repeating what people already know here but I have had quite a few conversations with suppliers on AliBaba over the last few days. Two in particular who are highly regarded on Will Prowse's DIY Solar Forum.

It is clear that what these suppliers call A grade cells are actually what the manufacturers (Catl, Eve, Rept etc) describe as B grade cells. One of them admitted this openly and the other one told me that what I was describing as A cells are actually "A+" cells. The manufacturers do not use + or - in their classifications.

Since new classification were introduced in 2020 (I think), Eve's policy has been to print a capital B across the QR code on their cells that do not meet the Automotive Grade certification tests. Apparently this can be up to 30% of cells tested and these are then auctioned off to the AliBaba types who sell them as Grade A. They replace or cover up the QR with a B.

I was looking for 280ah cells. Both suppliers offered me Real grade A (or A+) cells for around $140 each plus another $110 shipping. The "false" Grade A's are around $110 each plus another $110 shipping. So DDP to me in the UK around $700 for real A and $570 for false A's.

These costs converted to £stg are within whispering distances of the prices for certified Eve Grade A and Grade B cells on the Fogstar website.
I had a chat with Fogstar about their B cells and they indeed have the B on the QR code and have data as to the tested data on a small white sticker applied to the cell by Eve. Fogstar only sell cells that have tested above 277ah (for 20s). They provided me with this picture of one of these cells from their warehouse this morning which shows the B superimposed on the QR code and the test data on the little white sticker.

So long story short, given that they also guarantee the cells I have now bought 4 of these from Fogstar.

It is clear that lots of people who buy these from China get a perfectly good product and it is fascinating to see in the video that they all performed the same more or less in the tests.

I'm not sure if Fogstar are selling these cells particularly cheaply as a policy, but with the current state of the pound v Dollar and very high shipping costs, there does not seem to really be a financial advantage to the average Joe like me importing them from China in small quantities.

Anyway, just my experience which I hope helps someone. I will update when the cells arrive but I have ordered the BMS from China so have to wait on this anyway!

Cheers,
Sean

 

[Raul]

Battery 1 almost completed

 

[Raul]

I woke up the bms

 

[Raul]

Hopefully battery 2 will be completed by weekend, then I will hook up the multiplus for first charge, both in parallel.

^{_{Subscribers  do not see these advertisements}}

 

[SeanF1]

Hopefully battery 2 will be completed by weekend, then I will hook up the multiplus for first charge, both in parallel.

Looking good Raul. I top balanced mine over night.

 

[DavidCh]

Out of interest did you compress the batteries or decided it was not required? I spent hours of research, did compress mine but I am still not sure if I needed to?

 

[SeanF1]

Out of interest did you compress the batteries or decided it was not required? I spent hours of research, did compress mine but I am still not sure if I needed to?

Hi David,
Yes I did. Piece of 6mm ply each end, compressed with 4x2 and threaded bar, and wrapped with fibre tape whilst compressed. So far so good.

 

[DavidCh]

Neat solution.

 

[Raul]

In my case I built the ply box very tight, allowing a space for 1.5mm fibre board separator for each cell. Two fibre boards on the ends, so it has 3mm ish compression on a stack of 8 cells. At first full charge, I will take note if the plywood box will bulge out on the ends. At the moment they are not charged and quite snug, cells will not move if I tip the box on its side. I tend to agree that a restrain it’s better than compression, unless you can apply a even 12psi pressure. I have seen the way seplos build theirs, and they do not compress but restrain. Similar results are achieved with fibre tape.

^{_{Subscribers  do not see these advertisements}}

 

[SeanF1]

Neat solution.

Thanks.

 

[DavidCh]

In my case I built the ply box very tight, allowing a space for 1.5mm fibre board separator for each cell. Two fibre boards on the ends, so it has 3mm ish compression on a stack of 8 cells. At first full charge, I will take note if the plywood box will bulge out on the ends. At the moment they are not charged and quite snug, cells will not move if I tip the box on its side. I tend to agree that a restrain it’s better than compression, unless you can apply a even 12psi pressure. I have seen the way seplos build theirs, and they do not compress but restrain. Similar results are achieved with fibre tape.

Again, clever. Maybe I overthought mine

 

[Two on Tour]

I do not compress the cells in my battery packs as certainly the manufacturer of my cells does not indicate or state that the cells need to be compressed.
SeanF1 on what basis did you compress your cells, did the manufacturer of your cells advise this or was it because of those that promote the practice of doing so on Youtube?
I like Raul restain mine by binding the battery pack together, but I use Kapton tape as does Will Prowse.

 

[Two on Tour]

You may note that I use cable busbars and I fit them so that they have a slight curve in them.
This allows for some "give" when the cells expand so no putting strain on the terminal post of the cells as solid copper and aluminium busbars do when the cells expand and contract.

 

[SeanF1]

I do not compress the cells in my battery packs as certainly the manufacturer of my cells does not indicate or state that the cells need to be compressed.
SeanF1 on what basis did you compress your cells, did the manufacturer of your cells advise this or was it because of those that promote the practice of doing so on Youtube?
I like Raul restain mine by binding the battery pack together, but I use Kapton tape as does Will Prowse.

I am using eve cells and they recommend using 300kgf compression in their datasheet. I followed the Fibre Tape method used by Offgrid Power Solutions on YouTube as their approach made sense to me

^{_{Subscribers  do not see these advertisements}}

 

[DavidCh]

I can see you are using the same BMS as me (the JK). One issue I have is the voltage reported is incorrect. I get the same reading on my two multimeter’s and the victron which was different to the JK. I used that reading to calibrate the JK but it does not hold the calibration across the whole voltage range. In the end I set it when the batteries where at 50% but it is incorrect when fully charged by about 100mv. Have you encountered this?

 

[Two on Tour]

My CatL cells data sheet states that the inner walls of the cells aluminium container apply 300kgf to the cell contents.
Note that the arrows are internal and pointing outwards.
If pressure was required to the outer of the case, then the arrows would be outside of the case show pressure would need to be applied.

 

[Raul]

I can see you are using the same BMS as me (the JK). One issue I have is the voltage reported is incorrect. I get the same reading on my two multimeter’s and the victron which was different to the JK. I used that reading to calibrate the JK but it does not hold the calibration across the whole voltage range. In the end I set it when the batteries where at 50% but it is incorrect when fully charged by about 100mv. Have you encountered this?

I haven’t run my bms long enough to notice any accuracy as yet. But 100mv for the hole pack it’s nothing that concerns me. I always dial in conservative figures, then keep all charging sources below that at the top, and keep load alarm above the bms limits. I have oversized for my needs, so I won’t cycle the top and bottom ends at all. Unless it’s a emergency.

 

[SeanF1]

I can see you are using the same BMS as me (the JK). One issue I have is the voltage reported is incorrect. I get the same reading on my two multimeter’s and the victron which was different to the JK. I used that reading to calibrate the JK but it does not hold the calibration across the whole voltage range. In the end I set it when the batteries where at 50% but it is incorrect when fully charged by about 100mv. Have you encountered this?

Haven't run it long enough yet to notice anything like this. I put it together in 4s with the bms to charge it up to 14.3v then disconnected to put the cells in parallel to top balance. Left the cells in parallel after top balance completed and haven't put back to 4s yet.
How are you all capacity testing ?

 

[DavidCh]

Haven't run it long enough yet to notice anything like this. I put it together in 4s with the bms to charge it up to 14.3v then disconnected to put the cells in parallel to top balance. Left the cells in parallel after top balance completed and haven't put back to 4s yet.
How are you all capacity testing ?

I could not quit bring myself to buy a proper tester as to be honest it’s pretty irrelevant. I charged that battery to the max cell voltage, reset the victron, set the bms to cut off at minimum and switched enough on the camper to create a 10a load. Left it till the bms shut down, then recharged to full at 10a. Took the measurements from the victron and the bms. In my case the BMS showed 286 and the victron 281.

^{_{Subscribers  do not see these advertisements}}