Supplier defends lower capacity as being within 5% of stated capacity

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
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A reminder on a few points.
1) Charge a cell to 3.650 and allow to saturate till <2A is being taken. One hour rest will see it settle to 3.550 +-0.050, more likely closer to 3.500.
2) The primary voltage curve of LFP is 3.000-3.400, there is very little AH below or above these voltage. Remember LFP settles.
3) The NOMINAL voltage is 3.200 and that is where the Watt Hours are calculated. 3.2V*280AH=896Wh per cell * #ofCells (4)=3584, (8)=7168, (16)=14,336
4) Temperature DOES affect Charge & Discharge capacities. Nominal Test temperatures is 25°C/77°F

You can charge LFP cells to 3.650 until amps taken is ZERO and even leave it there for 24hrs charging at that rate, within an hour of power being removed they will settle to 3.500-3.550, within 12 hours they will sit around 3.450 without any charge going it. This is Completely Normal for this chemistry.

The Bulk Commodity ESS cells will vary much more and generally diverge somewhat above 3.400 and below 3.000 and that can be as much as 1mv per AH of capacity.

There are some links in my signature which would help you related to ESS Cells, Voltage Curves and such.
Hope it helps, Good Luck.
 

Johnson

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I'm of the mind that paying 1/3 to 1/2 the price for cells vs. those obtained through official distribution channels carries with it the expectation that the cells do not meet spec.
Not diagreeing that the cells are cheap, but it is bad marketing, if I bought a 272Ah cell (which is more than what I needed for my application) and it tests out at 274Ah, I am happy, if that same cell is sold to me at 280Ah I will be annoyed. I am also more likely to buy the cell from the "honest" supplier, even though they advertise the cell at a lower capacity.
 

Cdkipp

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Setting aside all the other arguments, but as Johnson says above this is crap. Legally this is a crap argument to use a more polite term. If 5% variation is the standard they use then they need to say that upfront before you make the buy. You gave the rating--nut a plus or minus. Exceed it or equal it or you are violating the terms of the contract. Of course, enforcing the contract against a Chinese company is another issue, but they should in no way be allowed to pretend this is acceptable especially to a group like this. If you buy into that argument, you buy into their misrepresentation and fraud.
 

Johnson

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Did the supplier request the cells be returned?
No, but that is what I would have expected. Even if they had let me keep them, I wouldn't have know what to do with them except sell them at the tested capacity, which would be unfair to the seller.

I want to add that I want them to stay in business, just up their game a little. The downside of being harsh, is that it will only make those things more expensive. Lying on the other hand, is not acceptable. And in this case a discount on the next order was enough for me.
 
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Gazoo

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Hi folks

I'm curious if this is quite common.
We decided, partly out of curiosity, to check out a few Alibaba sellers of cells.
We've received a set of 4x300ah cells a few weeks ago which have tested out at 285ah (four tests including high current at around 0.5C and low current at around 0.04C, three done at a controlled temperature of 25°C and one at a lower temp of 21°C).

Anyway, we got hold of the seller and challenged him. His response: as long as it's within 5% of stated capacity that would be acceptable.

Comments?
I don't agree with that type of response or suppliers advertising cells as new grade A cells. It's Alibaba and this type of advertising is common with these sellers.

Having said that your battery is 95% of the rated capacity of the cells rating. As suggested you could capacity test each cell but I don't think it's necessary. I passed on it. You can get a good idea of the runners from monitoring your BMS. One needs to take into consideration the price per wh paid and then decide if it's a good deal based on expectations.

I bought 8 280ah EVE cells and my battery tests at 272ah 0r 97% capacity. This is due to a couple of my cells being weak. At first I was a bit disappointed but after I realized my cost as compared to buying direct from the manufacturer, or paying for binned and capacity matched cells, I felt I got a great deal.

I do think it's good to call out the suppliers that are posting misleading ads with the hopes they will do better. In your case you could ask for a prorated refund type of thing which would be 5% of the cost of the cells if it would make you feel better. In my case I didn't bother since I got a good price on my cells.
 

Cdkipp

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I don't agree with that type of response or suppliers advertising cells as new grade A cells. It's Alibaba and this type of advertising is common with these sellers.

Having said that your battery is 95% of the rated capacity of the cells rating. As suggested you could capacity test each cell but I don't think it's necessary. I passed on it. You can get a good idea of the runners from monitoring your BMS. One needs to take into consideration the price per wh paid and then decide if it's a good deal based on expectations.

I bought 8 280ah EVE cells and my battery tests at 272ah 0r 97% capacity. This is due to a couple of my cells being weak. At first I was a bit disappointed but after I realized my cost as compared to buying direct from the manufacturer, or paying for binned and capacity matched cells, I felt I got a great deal.

I do think it's good to call out the suppliers that are posting misleading ads with the hopes they will do better. In your case you could ask for a prorated refund type of thing which would be 5% of the cost of the cells if it would make you feel better. In my case I didn't bother since I got a good price on my cells.
Right, that is the thing there are few issues (1) it is still a good deal even if the cells do not perform 100% so you take the chance (2) they should not be lying about their cells (3) we certainly should not let things get to the point where an acceptable response is "well everyone knows we lie"..
 

RGIvy

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A few people have asked me to name the supplier:
The vendor in question is Dongguan Huanhuan Energy Technology Co. They have been mentioned in some other threads, and not often in a positive light. I have no beef with the supplier, but I am planning to write a full review once all of this is concluded. I will leave a review on Alibaba once it's all done and dusted. The ball is currently in their court.

In answer to various questions, let me be very explicit on how we did the test.
1. Top balance to 3.65v using a desktop power supply. Let it rest for 4 hours.
2. Assembled the pack into series.
3. Low current capacity test at 25°C using a 150W adjustable Constant Current Electronic Load Battery Tester. The test was done at around 12-14amps. The tester can run up to 185w, and the battery pack finally produced 285ah.
4. Charged battery to 14.6v. Let it rest for 4 hours. Daly BMS final delta was less than 0.1v
5. High current capacity test at 25°C using a 300A shunt with a 2kw inverter and heater. The inverter cut out when the voltage reached 11v. This meant there was still some juice left in the cells, so ran the other tester until the BMS cut the discharge. Simply added up the ah to 284.5ah
6. Charge battery to 14.6v. Let it rest for 4 hours.
7. Repeat the test done in step 3 at 25°C. We made up new cables with decent lugs instead of those flimsy little crocodile clips that came with the tester. This test came out at 284.5, same as step 5.
8. Charged and rested again.
9. Repeat the test done in step 3 but this time at 21°C to prove a point to someone that disputed that 25°C is too high. Came out at 284.5ah

The consistency is quite something. Almost worrying - we’re used to a little bit of natural variation. We were quite consistent with charging and resting though. And, as mentioned, we have a constant temperature testing cabinet. Interesting that there is no difference between 25°C and 21°C

We used multiple devices to check the amps being drawn. Everything was agreeing within an amp or two.

Just for interest the cells have no QR code. We took this up with Dongguan Huanhuan Energy Technology but they have consistently dodged the question. Of course, they never stated anywhere that each cell would have a QR code so we don’t really have grounds for a dispute based on this.

We asked Dongguan Huanhuan Energy Technology for some documentation around tests performed on the cells and were told that they were 300ah .... period.

Our next step is going to be checking individual cells just to see what that adds up to. We know that one cell is weaker, but the other three were dropping rapidly when the BMS cut off. Still, I’d like to know so we’ll do the test.

Finally, I’m not disputing that the 285ah won’t work (and work well) in this particular installation. I’m not even saying it’s not a good deal. It’s just that in this particular market when we say 300ah we don’t really mean “up to 300” we mean “300 or more”. We did actually ask for 280ah cells but were told that are out of stock and for a little bit more money we could get 300ah.
 
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Not to be the one standing in the way of you and your pitchforks, but it is totally reasonable for something labeled as 280Ah to be 280Ah nominally and +/-5% in reality, whether reality means at the factory or once it reaches the customer. Unless you got a datasheet before you ordered which said "+5/-0%" capacity, rating typical values is very common in electronics. Just take a look at any integrated circuit specification sheet: it will have a "min", "typ", and "max" column, and usually only some values are filled out in each column for each parameter. That is the contract.

Without reading this whole thread I think sometimes people are complaining unnecessarily even though they paid dirt cheap prices for a grey-market product that doesn't even come with a spec sheet or any guarantees. If you want "+5/-0%" capacity, meaning it will be *at least* the stated capacity or your money back, you are going to spend a lot more money in the first place, because only a portion of the items produced by the factory meet that requirement. In reality every physical measurement and production process has a random distribution around the mean.
 

Johnson

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Not to be the one standing in the way of you and your pitchforks, but it is totally reasonable for something labeled as 280Ah to be 280Ah nominally and +/-5% in reality, whether reality means at the factory or once it reaches the customer
I am all for keeping those guys in business and to thrive. And when there are tolerances, they would need to do is advertise those tolerances upfront and not tell you after you bought and tested them. When I bought mine, the seller simply apologized and offered a discount on a future sale, they didn't try to defend it by saying 5% lower should be acceptable. It is not unreasonable to expect 280Ah cells when the seller advertised them as 280Ah (without the tolerances)
 

chrisski

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So what vendor would you recommend that is advertising something like 280 AH +- 5, and the average would be at 280 AH, not an average of -5% at 266 AH?

If no lithium vendors are doing this, would you be willing to switch back to FLA?
 

snoobler

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Where would you draw the line?
Yes. And once we establish a line what prevents them from lowering it again. The rated capacity is the line.

90%

China suppliers lie. Period. They will try to get away with whatever they think they can. They will tell you what you want to hear. I've made several purchases over the years, and I'm constantly contacted by Chinese suppliers pedaling junk. I have the data showing how inferior their product is, and they will just deny it over and over and claim how widespread and successful their product is.

A friend of mine has a million dollar/year battery business. He catches them routinely testing the boundaries. A shipment will come in, and 80% of it will be clearly matched. The remaining 20% is all over the map. He catches them. They apologize and say this has never happened before. The next two shipments are great with no issues. The 3rd to 4th shipment - boom... 20% garbage. Rinse and repeat... 9 years running.

If he didn't do as much testing as he does, he would have been out of business years ago.

Bottom line:

If you believe that you are purchasing "Grade A" cells from suppliers off Alibaba for a small fraction of the going price, you are gullible and have horribly unrealistic expectations. To believe that your standards of "honesty" apply in dealings with China based suppliers is just a misplaced sense of entitlement and disillusionment with how you think the world should be instead of how the world really is.

China: Buyer Beware. Always. Every. Single. Time.
 
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petee_c

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in pharmacy, the actual medication quantity of the tablet/capsule should be within somewhere between 5-7.5% of what is on the label...

ie a 100mg tablet may have between either 95-105mg or if it's 7.5% 92.5 to 107.5mg in each tablet.

It may also be a statistical reference. they sample the batch. They don't test every single tablet.

They don't ask you for 5% more money if you got cells that came with 315Ah......
 

Johnson

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They don't ask you for 5% more money if you got cells that came with 315Ah......
Of course not, but this is human nature, when we get more of something we want, we are happy with the seller, which means we are even more likely to refer the seller to others. When we get less , we complain and feel cheated, I know I do that as well. Personally I am willing to pay up to 10% more to buy from a supplier I can trust, then a supplier who tells it's customers after they bought the goods that 5% lower should be acceptable. Now if they put the +/-5% tolerance on the website, that would be fine, but when I compare them with other vendors, I would be rating those batteries at a 5% lower capacity than what is stated, as that is the minimum they promise to sell.

Now I am biased against advertisers to begin with, I have always been very skeptical, which is I know is unhealthy. I aggressively block all advertising and when sites insist on advertising, I stop going there rather than disable my add blocker. I do not watch tv because the advertising is crazy. When I look for something, I expect to get at least what the item is sold at and assume the lowest when they post the tolerance.

And even so, I left an angry message with the vendor even though I let the vendor get away with it by not asking for a partial refund. I just posted a warning in here like the OP.
 
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Bottom line:

If you believe that you are purchasing "Grade A" cells from suppliers off Alibaba for a small fraction of the going price, you are gullible and have horribly unrealistic expectations. To believe that your standards of "honesty" apply in dealings with China based suppliers is just a misplaced sense of entitlement and disillusionment with how you think the world should be instead of how the world really is.

China: Buyer Beware. Always. Every. Single. Time.
Cool story bro.
In my opinion the market gets what it accepts.
 

snoobler

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Cool story bro.
In my opinion the market gets what it accepts.

Your opinion will not change the way China does business. It's a culture thing.

We're volunteering to purchase cells that have NO manufacturer's warranty. The only potential support you may get is if you have the capacity to harm the vendor's market, i.e., by telling everybody on this forum, they won't support what they sell. I am personally aware of a user who got "sorry, we can't help," until they indicated they would share their negative experience on this forum... Now replacement cells are on the way.

If you were buying a name-brand product from a North American vendor, and they told you the manufacturer does not offer a warranty with this purchase, would you actually make that purchase? If your answer is "no," then you don't consistently apply your philosophy with these grey market cells.
 
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Your opinion will not change the way China does business. It's a culture thing.
Mine alone won't but I'm confident the market as a whole can.
All cultures lie, China more so it seems.
But I think the saying "Money talks and bullshit walks" still applies, even in China.
 

snoobler

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Mine alone won't but I'm confident the market as a whole can.
All cultures lie, China more so it seems.
But I think the saying "Money talks and bullshit walks" still applies, even in China.

The problem is the bullshit isn't walking. It's talking, and the money is buying it. The market is perpetuating it and will continue to do so on the false promises of non-conforming products sold way below market value.

Buy an EVE, Fortune, CALB, etc. cell from an authorized distributor? You have every right to jump up and down and scream bloody murder if capacity is missed by even a single mAh, and you should expect to be supported. Buying from sources that are selling known "cast-offs"? You just bought the bullshit.
 
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