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diy solar

Are we all getting GRADE B cells??

RobertGreen said:
I just want to buy cells which are newly manufactured, unused, and which meet the manufacturers specifications in every way, while lacking any type of defect.
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Don’t we all. I bet you wouldn’t want to pay for them though!

It’s unfortunate you can’t put a price on a battery until it has failed - i still don’t know the $/kwh of my 11 year old cells.

Judging by the premature failures i’m seeing in the pylontech batteries, as well as the early buyers of the “cheap” CATL aluminium cells - i don’t hold much hope for the EVE / Lishen / CATL etc “backdoor” cells.

Another 5 years will paint a clear picture, and for those saying “who cares - we’ll all be using something different then” remember that was being said about LiFePO4 over a decade ago and nothing has changed.
 
toms said:
Judging by the premature failures i’m seeing in the pylontech batteries, as well as the early buyers of the “cheap” CATL aluminium cells
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edit: I've heard of users here receiving 'bloated' cheap CATL aluminum cells in recent years, but IDK if that's what you're referring to...

I'm curious if you can say more about the particulars of this... I'm specifically interested as to how or why these failures are happening, and if the commonly understood factors which are supposed to prolong cycle life in lifepo4 cells would have helped(reasonable storage temperature, conservative charge/discharge currents, conservative SOC profile such as 20%-90% etc)
Or are you saying that the cells are failing due to poor construction or other problems which users have no control over?
 
RobertGreen said:
edit: I've heard of users here receiving 'bloated' cheap CATL aluminum cells in recent years, but IDK if that's what you're referring to...

I'm curious if you can say more about the particulars of this... I'm specifically interested as to how or why these failures are happening, and if the commonly understood factors which are supposed to prolong cycle life in lifepo4 cells would have helped(reasonable storage temperature, conservative charge/discharge currents, conservative SOC profile such as 20%-90% etc)
Or are you saying that the cells are failing due to poor construction or other problems which users have no control over?
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these "cheap" CATL cells are most certainly comming out of busses/other high c-rate applications and are nowhere near good cells.
from what i found the CATL cells are a bit more prone to swelling, but as long as they are fixated as recommended by CATL there's no issue with them.

kind of like 'RTFM" and keep it within spec
 
RV10flyer said:
I have a 132kWh battery bank.

Three out of four of Amy's - Schenzen Luyuan "Grade A" 280aH 16S batteries do not have runners when I charge above 55.7V.

One out of four of Hayley's - Dongguan Lightning do not have runners above 55.7V.

Sanben's 320aH (really 304aH) and Trophy 220 aH both have runners above 55.7V.

FOUR out of ten batteries, I can take all the way to 57.6V or 3.6V per cell without having extra cell balancers installed. Just 10 individual BMS's with 0.15-2.0A balance current.

That is some poor manufacturing and QC. Sad. I stay just under 55.7V when charging and don't lose that much capacity. It's not a huge problem, just buy one more battery than you have planned. Along with 25% more pv? and you'll be fine.
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I have very similar results.

I tend not to charge mine more than 55V because they settle to 55v fairly quickly regardless how high I charge them.

I still have 4 batteries with the Heltech Balancer on them because of some runners early on.

The one with the balancers stay balanced almost all the way to 3.65 but like I said they settle quickly so rarely get charged that high.

The one without balancers vary but usually above 3.4 -3.5 they start divergent.

The balancers are nice but since the batteries like to stay around 55v I could probably do without them.

Yes they have all been top balanced.

All Cells (176) came from Docan and Shenzhen Qishou.
 
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toms said:
Don’t we all. I bet you wouldn’t want to pay for them though!
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The matched and batched 280Ah cells from Shenzhen Luyuan are $190US now (what some would call the "best" china vendor reviewed here).

We don't really know the source of their cells. They could be automotive grade, but could also just be new cells that EVE rejected because they didn't meet the automotive grade spec. I believe the general consensus/belief in this thread, is that they are likely the latter, and that this is the case for most of the reputable sources ppl buy from on this forum. And the less reputable vendors try to even get away with selling used cells, or just plain junk (see the post where buddy found blocks of granite in the battery to make it weigh more).

If you look at sunfunkits site (people who made the video in the OP), they assert that they are buying the automotive grade cells from EVE and on their site they are $925US for four 280Ah cells, or ~$231US each. Whether they are worth an additional $40US/cell, is for anyone to decide on their own I guess. I am sure they are "better" cells but whether it matters in practice for non-automotive applications (solar = lower charge/discharge rates from automotive), I'm not sure.
 
Actually found this buried in the Q&A on the sunfunkits website:
1651236371946.png

So that does sound somewhat re-assuring that Shenzhen Luyuans "Grade A" cells are perhaps the automotive quality cells from EVE.
 
houseofancients said:
this is true, but 125 vs 169 luyuan both unshipped is quite the difference
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I have 1 runner out of 64 cells from Amy. I have 3 runners out of 64 cells from Hayley's. My Sanben and Trophy batteries both have runners.


My recommendation is to just buy an extra cell for each 16S battery and that will cover runners and damaged cells. Are Amy's worth the extra money? Well, it depends on if you have spare cells and how much time you have to tinker with them.

Out of 10 16S batteries (132kWh), 4 can go above a charge of 55.7V without going off on a cell OVP.

We are not getting 100% Grade A cells that should be able to go to at least 3.60V/cell.
 
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RV10flyer said:
I have 1 runner out of 64 cells from Amy. I have 3 runners out of 64 cells from Hayley's. My Sanben and Trophy batteries both have runners.

My recommendation is to just buy an extra cell for each 16S battery and that will cover runners and damaged cells. Are Amy's worth the extra money? Well, it depends on if you have spare cells and how much time you have to tinker with them.
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What is the description of runners please?
 
Is it a runner if it doesn’t increase dramatically until after >3.5v?
 
flemmingdjensen said:
I have a facebook group in Danish where we build LFP batteries for our boats and since I opened the group I have recommended Basen Tech as being a reliabel supplier of GRADE A cells...

Now my frinds have bought 16 x 304AH CATL and they do not seem to be GRADE A. QR code seems to be scratched away and a few cells has minor dents in the casing.

I looked at this video yesterday saying that if we do not get certificates and Excel spreadsheets with test results for each cell then we are dealing with GRADE B...

Is this correct? Are we all getting rejected cells that cannot be used for fx Automotive purposes?

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This video contains the exact info that I was told by Fortress Power and two sellers including Eco-Direct.
Fortress Power has the certificates for the each cell in each pack.
The bottom line that all three companies told me was the same thing. If the price of a cell or pack is half that of a reliable Tier One battery Suppliers equivalent product then the Cells are Grade B.

Now IMO if they last at least half as long as a Grade A cell then there is really no loss involved for the buyer and it's not a bad deal.

Dunno why this is such a hard concept for some people on this forum to accept. If someone is selling you a "Brand New" F150 Pickup for half the Price that a Ford dealer sells it for then you pretty much know something is up! But for some reason in the LFP battery world this logic gets thrown out the window.
 
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IMO more along the lines of I don’t buy “Honey Nut Cheerios”, I save a few bucks and enjoy “Honey Toasted Os” end product is so close that I gladly save a few bucks and never notice the change in quality.
 
740GLE said:
IMO more along the lines of I don’t buy “Honey Nut Cheerios”, I save a few bucks and enjoy “Honey Toasted Os” end product is so close that I gladly save a few bucks and never notice the change in quality.
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Unfortunately their are only about 5 factories in China that make LFP batteries and all of them are making Grade A cells to meet the Standards of the EV market, because that is where the money is. So there is no low priced lower quality manufacturing being done. The only thing that is available for cheap is the 10% of new batteries that are rejects or old Grade A cells that are being replaced and can be dispossed of on the grey market.
 
And you think there are hundreds of factories making “Honey Toasted Os” for each house brand? ?‍♂️
 
740GLE said:
And you think there are hundreds of factories making “Honey Toasted Os” for each house brand? ?‍♂️
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As I said logic flies out the window on this subject, so whatever makes you feel better?
 
Sometimes you just can’t help people. I’ve seen hundreds try to get a “good deal” over the last decade or so on cells or electronics. I’m yet to see one last the distance.

I guess it depends on expectation also - if i only want my cells to last 5-7 years, seconds might be an option.

If you think you’ll get anything close to 15 years out of your Alibaba grade A+++ cells, you are dreaming.
 
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