Severe capacity degradation of 280Ah cells -- warning!

Wavepax

Solar Enthusiast
I ordered 16 280Ah Varicore cells for $2020 via AliExpress from the LiitokalaVariCoreFlagship Store. It took two months for the cells to be delivered from China to Arizona.

All 16 cells were capacity tested with an EBC-A40L tester upon receipt, and all cells tested to 85% of 280Ah advertised capacity. An average of 238Ah capacity was measured for all 16 cells.

Below is the capacity test result for cell 6 (238.1Ah measured capacity). The capacity test results for cells 5-12 are attached. The blue curve is voltage in volts, the red curve is amperage in amps, and the horizontal axis is time in hours. The capacity test results are in Ah and the energy units are Wh. The test charged the cell fully using 3.65V, followed by a 30 minute wait, followed by a discharge at 40A until 2.5V reached, then charged at the end in order not to leave the cell in a discharged state. The max charging and discharging rate for the EBC-A40L tester is 40 amps, corresponding to 0.143C for these cells.


Cell 6 Max Capacity Test.JPG

The manufacturer specifications for these cells shows capacity degradation vs. cycle below. The horizontal axis is cycle number and the vertical axis is percent of 280Ah capacity. We see that 85% measured capacity corresponds to 2750 cycle loss. The lifetime cycles was advertised to be 4000 cycles for these cells.

Varicore 280Ah cell cycle vs capacity curve.JPG

Lifetime Ah is defined as the total Ah over all 4000 cycles. Percent Lifetime Ah loss of these cells = the area under the above curve out to 2750 cycles divided by the area under the curve out to 4000 cycles. Doing that calculus, Lifetime Ah loss = 73.4%. I disputed the transaction and requested a 73.4% refund based upon Lifetime Ah loss.

I paid for 8 of the cells with a credit card and 8 of the cells with Paypal. All were bought on the same day in May 2021. AliExpress dispute resolution was horrible. They resisted the 73.4% refund, sided with the seller fraud, and closed the dispute associated with each package of 4 cells. In response, I contacted my credit card company and Paypal. The credit card company, Chase, was excellent. My credit card now shows a full refund. Paypal dispute resolution has so far been horrible. Paypal completely ignored all the definitive evidence that I provided. That evidence took over two weeks to measure. You never get to talk with the person making the dispute resolution decision. The initial response from Paypal was to side with the fraud committed by the seller and close the dispute. I called Paypal twice after they sided with the seller fraud. The first person refused to reopen the dispute. The second person correctly reopened the dispute. You never get to talk to the Paypal dispute "judge" to make sure they understand the evidence. The first anonymous Paypal "judge" response did not address the evidence. It's as if they didn't at all understand the evidence and just skipped it. Anonymous backroom blackbox "judges" in the Paypal dispute resolution have so far been horrible.

This is not the first time that I have experienced fraud from a seller on AliExpress. I ordered 500g of what was supposed to be Nicotinomide Riboside. It failed a basic melting point test and taste test. The seller sent a sugar. I submitted a picture of the melting point test and got my money refunded. However, the seller was allowed to continue to sell the same fraudulent product on AliExpress, so I submitted a review with pictures of the melting point test. The seller delisted the product to erase the review and relisted the exact same product on AliExpress. AliExpress allows proven fraudulent sellers to continue to use their platform. This is one reason why there are so many fraudulent sellers on AliExpress.
 

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MurphyGuy

Solar Addict
Credit card companies are fantastic at protecting their customers.. Paypal is as well but only under some conditions. I'm kind of surprised they didn't protect you in your case.. really surprised.

Lessons learned 1) China makes garbage 2) China inflates all numbers 3) Use your credit card.

I won't buy anything more important than a keyboard from China.. and NEVER EVER directly, always through a big box distributor.
 

Wavepax

Solar Enthusiast
Agreed. Exactly.

An update -- Paypal improperly closed a dispute on 4 of the cells and kept the dispute open on the other 4 cells. All the cells have the same capacity degradation issues, so that alone shows incompetent inconsistency.

Since Paypal is supporting fraud and false advertising by the seller, I will take them to court. Is small claims court an option? Time to consult consumer law and Nolan references.
 

Gadgetnerd

Solar Enthusiast
I ordered 16 280Ah Varicore cells for $2020 via AliExpress from the LiitokalaVariCoreFlagship Store. It took two months for the cells to be delivered from China to Arizona.

All 16 cells were capacity tested with an EBC-A40L tester upon receipt, and all cells tested to 85% of 280Ah advertised capacity. An average of 238Ah capacity was measured for all 16 cells.

Below is the capacity test result for cell 6 (238.1Ah measured capacity). The capacity test results for cells 5-12 are attached. The blue curve is voltage in volts, the red curve is amperage in amps, and the horizontal axis is time in hours. The capacity test results are in Ah and the energy units are Wh. The test charged the cell fully using 3.65V, followed by a 30 minute wait, followed by a discharge at 40A until 2.5V reached, then charged at the end in order not to leave the cell in a discharged state. The max charging and discharging rate for the EBC-A40L tester is 40 amps, corresponding to 0.143C for these cells.


View attachment 66454

The manufacturer specifications for these cells shows capacity degradation vs. cycle below. The horizontal axis is cycle number and the vertical axis is percent of 280Ah capacity. We see that 85% measured capacity corresponds to 2750 cycle loss. The lifetime cycles was advertised to be 4000 cycles for these cells.

View attachment 66446

Lifetime Ah is defined as the total Ah over all 4000 cycles. Percent Lifetime Ah loss of these cells = the area under the above curve out to 2750 cycles divided by the area under the curve out to 4000 cycles. Doing that calculus, Lifetime Ah loss = 73.4%. I disputed the transaction and requested a 73.4% refund based upon Lifetime Ah loss.

I paid for 8 of the cells with a credit card and 8 of the cells with Paypal. All were bought on the same day in May 2021. AliExpress dispute resolution was horrible. They resisted the 73.4% refund, sided with the seller fraud, and closed the dispute associated with each package of 4 cells. In response, I contacted my credit card company and Paypal. The credit card company, Chase, was excellent. My credit card now shows a full refund. Paypal dispute resolution has so far been horrible. Paypal completely ignored all the definitive evidence that I provided. That evidence took over two weeks to measure. You never get to talk with the person making the dispute resolution decision. The initial response from Paypal was to side with the fraud committed by the seller and close the dispute. I called Paypal twice after they sided with the seller fraud. The first person refused to reopen the dispute. The second person correctly reopened the dispute. You never get to talk to the Paypal dispute "judge" to make sure they understand the evidence. The first anonymous Paypal "judge" response did not address the evidence. It's as if they didn't at all understand the evidence and just skipped it. Anonymous backroom blackbox "judges" in the Paypal dispute resolution have so far been horrible.

This is not the first time that I have experienced fraud from a seller on AliExpress. I ordered 500g of what was supposed to be Nicotinomide Riboside. It failed a basic melting point test and taste test. The seller sent a sugar. I submitted a picture of the melting point test and got my money refunded. However, the seller was allowed to continue to sell the same fraudulent product on AliExpress, so I submitted a review with pictures of the melting point test. The seller delisted the product to erase the review and relisted the exact same product on AliExpress. AliExpress allows proven fraudulent sellers to continue to use their platform. This is one reason why there are so many fraudulent sellers on AliExpress.
How is the discharge of a 280ah cell at 40 amps a rate of .143C? (from original testing comment) Never heard of the company, sucks the batteries didn't meet spec, and yeah, always pay with a cc for the reasons you state above. I would recommend Gloria at Basen, I guess I was lucky.
 

Wavepax

Solar Enthusiast
How is the discharge of a 280ah cell at 40 amps a rate of .143C? (from original testing comment) Never heard of the company, sucks the batteries didn't meet spec, and yeah, always pay with a cc for the reasons you state above. I would recommend Gloria at Basen, I guess I was lucky.

40/280 = 0.143. 1C is 280A for a 280Ah cell.

Will Prowse had a video from Jan 2021 about 280Ah cells from the same seller but different cell manufacturer. I tested Varicore cells. Will tested Eve cells. Will didn't experience the capacity fraud with the Eve cells like I did with the Varicore cells.

I will look at Basen. All LiFePO4 roads point to Shenzhen it seems.
 

MattiFin

Solar Addict
Not suprise with Liitokala-Varicore. They have been "famous" in flashlight community because of their counterfeit or recycled 18650 batteries.

Aliexpress is a wild west bazaar and in generally Chinese way of doing business&ethics are different from what you are used to.
 

Short_Shot

Photon Sorcerer
Same seller. 86% expected capacity.

I didn't request as much of a refund as you but if they don't give me all of it, I'll be contacting the credit card company.

Also purchased at Wills recommendation.
 

Gadgetnerd

Solar Enthusiast
I just take 280 divide it by 40 (7) (which is how many hours to charge/discharge at that rate) and invert, easier on the brain...lol Yeah Basen/Eve is the route I took. First I calculated 280ah was the best value, then it was a tossup between Eve and Lishen brands, then saw some failed capacity tests and deformed cells with Lishen so that's how I arrived at Eve. Having said that who even knows what's what, it just has a frickin' sticker on it....:)
 

Gadgetnerd

Solar Enthusiast
Not suprise with Liitokala-Varicore. They have been "famous" in flashlight community because of their counterfeit or recycled 18650 batteries.

Aliexpress is a wild west bazaar and in generally Chinese way of doing business&ethics are different from what you are used to.
Hey in China Alibaba was/is a bit of a joke especially early on. Ordering a watering can and getting a front-end loader. Heard similar tales about Dragon Mart there.....:ROFLMAO: Yeah, there you are allowed to be late to a meeting if you are the seller, but not the buyer. Also if you get ripped off its on you for being taken apparently. (the shame) :rolleyes:
 

Short_Shot

Photon Sorcerer
Yeah I'm not thrilled. I'm glad there's a couple of known decent sellers, at least one with a US warehouse, and I hope the trend continues by their success.
 
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Gadgetnerd

Solar Enthusiast
Yeah I'm not thrilled. I'm glad there's a couple of known decent sellers, at least one with a US warehouse, and I hope the trend continues by their success.
I guess there's a risk, but the savings are huge. I mean 16 280ah Eve cells @ 48V =13.4kwh for $1600. Spend that on 1.5 Battleborns gets you 150ah @ 12V or 1.8kwh.... :ROFLMAO:
 

Short_Shot

Photon Sorcerer
I guess there's a risk, but the savings are huge. I mean 16 280ah Eve cells @ 48V =13.4kwh for $1600. Spend that on 1.5 Battleborns gets you 150ah @ 12V or 1.8kwh.... :ROFLMAO:
Sure. Except instead of 280ah I got 240ah and almost certainly have 1/3 of the rated cycle life remaining. If that. The reason the cells have such low capacity is because they're already used and degraded, since they seem to meet all the other specs of weight and size you'd expect for the 280ah.

The risk is negated by spending slightly more on known good cells from a known good seller.
 

Gadgetnerd

Solar Enthusiast
Sure. Except instead of 280ah I got 240ah and almost certainly have 1/3 of the rated cycle life remaining. If that. The reason the cells have such low capacity is because they're already used and degraded, since they seem to meet all the other specs of weight and size you'd expect for the 280ah.

The risk is negated by spending slightly more on known good cells from a known good seller.
Even at 240ah its still 5x the capacity rather than 7x. Even better if you negotiate a refund.
 

curiouscarbon

Science Penguin
240 for a 280 ad is bad

sorry you got ripped off

good job on the lifetime calculations. i came up with slightly less than 70 but i think it’s clear that if 280 was the beginning point, 240Ah is definitely more than half way to end of life condition

thank you for educating others about this unfortunate undershooting of specification
 

Wavepax

Solar Enthusiast
Thanks. Yeah, if you do linear approximations to the curve when calculating the area under the curve, then 70% lifetime Ah degradation is what I get also.

The lifetime Ah calculation assumes the cells capacity degrade according to spec. Since the cells failed capacity testing, I would not at all be surprised if they failed cycle testing. With my 40A tester, it would take way too long to repeat that test. The capacity degradation curve above was cycling at 1C (280A current), which would lower the test time to 146 days for 3500 cycles.

I cycled cell 12 for 3 additional cycles to see if the capacity would drop off noticeably. I measured

Cycle #Capacity (Ah)
1238.3
2237.1
3237.5
4237.5

The number of cycles is too low to conclude anything, but the drop from the 1st to 2nd cycle is concerning and all subsequent cycle measurements where lower than the first cycle. That drop is way faster than the spec.
 

curiouscarbon

Science Penguin
Someone linked this recently and I hope it’s not weird to link it here in context of LiFePO4 cell degradation:

It’s kind of long and definitely recommend 1.25x playback speed. some interesting info maybe. under the header of general info.

thanks again for posting your analysis!
 

MurphyGuy

Solar Addict
I found this gem of a website giving very detailed advise on how to take Paypal to small claims court.

http://www.screw-paypal.com/resources/small_claims_court.html
That is not a "gem of a website", in fact, websites like that are a virus and do more harm than good.

If people start taking paypal to court over silly small garbage, paypal will simply update their user agreements to include a provision for mandatory arbitration.. and once they do that, everyone loses.

I'm not suggesting that a a lithium battery bank costing hundreds or thousands of dollars is "silly small garbage" by any means.. but that screw paypal website, and others like it, are the result of spoiled little brats who didn't get the right sized shoes or read the fine print when they hit the buy-it-now button.

Here is something to consider.. The website lists the battery's amp-hour rating at 280.. but how was that amp hour rating determined? The OP said he did a 40 amp discharge.. what if the AH rating was done by the manufacturer at 20 amps? Or 10 amps? As the current draw goes down, so does the discharge hysteresis, which results in the battery reaching its cut-off voltage at a later time, which results in a higher amp hour result.

A quick google search for the product shows no specifications about this rating..

The OP chose 40 amps.. why not choose 100 amps or 0.5 amps?
Max and nominal discharge ratings are not related to overall battery capacity..
 
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