Does it feel like there have been more reports of failure, poorly matched cells, and dissapointment in the last 3ish months?

I haven't kept a tally or anything, but anecdotally it feels like there have been substantially more reports of failures, bloating, bad cells, poorly matched cells in the last few months (summer, maybe late spring too). Not like a huge number by any means, and in most cases rather moderate problems, but it seems reports are more common than in the first 6 months of this forums existence.

Maybe just my perception. What do you think? Have you noticed something similar?

Agreed, it does seem like there are more posts in that vein, but probably just related to the number of people building their own batteries, lack of experience doing it leading to failed cells and not forgetting that the community is becoming more confident purchasing direct from China and being more inclined to take a risk with new sellers, rather than a general decline in the quality of the cells. That's just my feelings of it anyway.

gnubie said:

Agreed, it does seem like there are more posts in that vein, but probably just related to the number of people building their own batteries, lack of experience doing it leading to failed cells and not forgetting that the community is becoming more confident purchasing direct from China and being more inclined to take a risk with new sellers, rather than a general decline in the quality of the cells. That's just my feelings of it anyway.

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That is certainly one reasonable possibility, and I suspect is at the least part of the reason.

I have also noticed a positive trend, which is that more and more people are documenting or reporting on their purchase+balancing+test+build, this could also be a factor contributing to the perception of more problems/issues/failures--simply greater visibility and awareness of the problems that do arise. Which is a good thing, particularly the more systematically this is documented.

Dzl said:

anecdotally it feels like there have been substantially more reports of failures, bloating, bad cells, poorly matched cells in the last few months (summer, maybe late spring too).

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It definitely does. I would not be surprised if the increase is coincident with the number of sales in the 4 months that I have been on this site. Of course I would have to discount the puffies since in every case it appeared to me there was some contribution of the user. I reported two out of 32 cells as having less capacity and two more were sagging under load. On further testing the capcity came back on the ones I had earlier reported with low capacity. The cells that were sagging under load were resolved by tightening the buss bars.

Ampster said:

It definitely does. I would not be surprised if the increase is coincident with the number of sales in the 4 months that I have been on this site. Of course I would have to discount the puffies since in every case it appeared to me there was some contribution of the user. I reported two out of 32 cells as having less capacity and two more were sagging under load. On further testing the capcity came back on the ones I had earlier reported with low capacity. The cells that were sagging under load were resolved by tightening the buss bars.

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My impression is most of the problems are user error.

There is a lot of shoot first and ask questions later going on.
I think that has increased in the last few monthes.

smoothJoey said:

My impression is most of the problems are user error.

There is a lot of shoot first and ask questions later going on.
I think that has increased in the last few monthes.

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I feel that this is at least a big part of it. I think its a combination of user error (lack of research/due diligence), and maybe over confidence in certain cells/suppliers that new members don't really realize are still very new to us. Obviously I think everyone should be doing their due diligence and research, but I also think its partially on us to remind people that the trade-off for the huge savings of a DIY battery with grey market cells is (1) you are taking on the responsibility to know what you are doing and not screw up, and (2) buying from grey market Chinese suppliers comes with more risk (and variability as well). I find that these two cautions are often unstated or downplayed.

DIY batteries w/ grey market cells can be a great value for low C-rate, non-critical, energy storage applications, and I do encourage people down that path frequently. But I think a proper accounting of risks and trade-offs is important, and I think those of us who spend a lot of time in the beginners sections should be careful not to push people towards that path if they seem scared, or unwilling or unenthusiastic about learning.

I think @Will Prowse's early DIY battery bank videos strike a good balance between "You can totally do this, its not too difficult!" while at the same time conveying "this is not for beginners, you could screw things up if you aren't careful, and their is risk and uncertainty buying used cells on ebay, or grey market cells from China... Buuuut you can do it!"

Maybe I am especially sensitive to this because, I myself am new to all this as well, or because I don't have a lot of money to throw around. But it seems like some of the disappointment is explained by lack of due diligence and unrealistic expectations (many new forums members think the EVE cells are verified, well matched, grade-A cells, the former doesn't appear to be true and the latter is possible but not verifiable). And at least a handful of newbies are building batteries without understanding the difference between cell level and pack level voltages and without understanding the role or purpose or usefulness of a BMS.

I think probably if some people went in with more realistic expectations, and spent more time up front understanding what they are doing and how to do it safely and correctly, we would probably be seeing less disappointment.

In my opinion too many people try to get 100% of the capacity out of their cells by playing with cell voltages that are on or very near to the edge and where issues with cells such as bloating can arise very quickly when not paying attention. Everyone should look at this curve and think: is it really needed to go to 3.65V if you can get to 99% capacity at 3.5V with substantially less risk to damaging the cells, and what current am I actually sending to the cell. Same reasoning at the lower end of the curve.



In addition: be patient; don't just try stuff out with your cells until you have the BMS and have it all configured. No quick tests, no hooking up the charge controller, etc. Take your time, make sure the connections are all good, verify everything twice, measure, and don't do anything without a BMS attached and verified working unless it's not your first rodeo.

I think there has been an uptick in problems also .... to me it seems like the increase started when there was a temporary lack of 280 cells available .... and then a new batch came in and they started flowing again.
I'm sure there are also a LOT more batteries being ordered and reported on .... so, it's pretty hard to tell for sure.

upnorthandpersonal said:

In my opinion too many people try to get 100% of the capacity out of their cells by playing with cell voltages that are on or very near to the edge and where issues with cells such as bloating can arise very quickly when not paying attention. Everyone should look at this curve and think: is it really needed to go to 3.65V if you can get to 99% capacity at 3.5V with substantially less risk to damaging the cells, and what current am I actually sending to the cell.

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This is the graph that first conveyed that sentiment to me (from the MarineHowTo article):



In general I think the tone and quality of the MarineHowTo and Nordkyn articles are great. They (particularly the marinehowto article) make you trudge through all the negatives, risks, caveats, qualifiers, disclaimers, and warnings, and spend time upfront talking about the fundamentals of the chemistry, and system design, and how to do it right. Which is important.

I wonder if y'all have any thoughts on this situation (i linked to the point in the thread where things go south for OP--see the first page for context, OP was happy and had seemingly healthy cells up to the point of the linked post). OP is not exceedingly forthcoming with details, and skips over the majority of clarifying and context questions, so its hard to get a good picture of whats going on, but there is certainly some (to me unexplained) weirdness going on, that I don't recall seeing before. Cells are EVE, seller is Senberry, problems start occuring after seemingly normal top balance and capacity test.

edit: fixed link

Dzl said:

I wonder if y'all have any thoughts on this situation (i linked to the point in the thread where things go south for OP--see the first page for context, OP was happy and had seemingly healthy cells up to the point of the linked post). OP is not exceedingly forthcoming with details, and skips over the majority of clarifying and context questions, so its hard to get a good picture of whats going on, but there is certainly some (to me unexplained) weirdness going on, that I don't recall seeing before. Cells are EVE, seller is Senberry, problems start occuring after seemingly normal top balance and capacity test.

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Your link isn't working

I have seen a lot of shotgun style builds, where users have little understanding of the chemistry, how BMS function, and how to configure them. 70% or more cases where cell failure is observed, it appears that user error is the primary cause.

Now low capacity is another matter, and there have been a few reports of that. Some of which may be measurement error, and some are legitimate low capacity cells. That's the small risk we take buying grey market cells at a fraction the price of USA distributed.

https://diysolarforum.com/posts/129911/ (correct link)

Dzl said:

OP is not exceedingly forthcoming with details, and skips over the majority of clarifying and context questions, so its hard to get a good picture of whats going on, but there is certainly some (to me unexplained) weirdness going on, that I don't recall seeing before. Cells are EVE, seller is Senberry, problems start occuring after seemingly normal top balance and capacity test.

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When the user skips over the clarifying questions I generally move on.
IMHO its usually a waste of time trying to help people who won't help you help them.

ArthurEld said:

Your link isn't working

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Thanks Arthur, fixed link

There are a lot of things in there that make no sense whatsoever. If the cells were charged to 3.65V and then placed in parallel overnight .... and then the BMS connected and sit in storage mode overnight .... how would some of the cells suddenly be too high?
Also at that point he indicated with a meter cell 9 showed too high even though it was OK on the BMS ... then suddenly cell 10 is showing way too high on the BMS. I think it is not possible to figure out what is going on based on the info provided.

smoothJoey said:

When the user skips over the clarifying questions I generally move on.
IMHO its usually a waste of time trying people who won't help you help them.

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Normally I agree,
However, in this case:

• Its 32 x 280Ah cells (2 packs of 16). It pains me to think about losing that kinda money. And it also confuses me how even if the seller has poor QA or no QA, how one large order could have so many faulty cells, particularly after seemingly successful balance and capacity test. Almost equally unlikely is 2 x malfunctioning Chargery BMS'.
• Its one of the first three orders to arrive, from a seller I'm interested in, so I'm motivated to understand what happened, and interested in the situation being portrayed accurately.
• Its strange enough, and different enough from other failures I've read about to make me very curious to understand what the hell is going on.

But it is mildly frustrating that OP is not really documenting his process or his problem in detail and moved pretty quickly to try to get the seller to cover a replacement seemingly without taking the time or fully making the effort to understand what went wrong and/or document his experience for others to learn from. But I can understand how documenting the problem might not be his first concern at the moment.

Bob B said:

There are a lot of things in there that make no sense whatsoever. If the cells were charged to 3.65V and then placed in parallel overnight .... and then the BMS connected and sit in storage mode overnight .... how would some of the cells suddenly be too high?
Also at that point he indicated with a meter cell 9 showed too high even though it was OK on the BMS ... then suddenly cell 10 is showing way too high on the BMS. I think it is not possible to figure out what is going on based on the info provided.

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I agree, I was particularly perplexed by that part, (All his cells in the second pack settled to 3.3xx, (3.373 +/- 25mV) after a top balance to 3.65 (+/- 5mV), and felt this indicated the cells were bad, and then apparently with no further catalyst the cells started jumping all over the place (as high as 3.9V) and the pack voltage somehow rose by 2 volts, Could this occur with no external catalyst?)

I don't feel confident enough in my understanding of battery chemistry or dynamics to fully understand what is going on here, but it seems quite strange.

Dzl said:

I agree, I was particularly perplexed by that part, (All his cells in the second pack settled to 3.3xx, (3.373 +/- 25mV) after a top balance to 3.65 (+/- 5mV), and felt this indicated the cells were bad, and then apparently with no further catalyst the cells started jumping all over the place (as high as 3.9V) and the pack voltage somehow rose by 2 volts, Could this occur with no external catalyst?)

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As you said the poster noted he had a successful top balance and capacity test with zero issues. However the poster began by parallel top balancing and when he realized how long it was going to take he charged up the packs and then went back to top balancing. I don't know if this plays into any of this. The capacity test went well and no cells were swollen at this point.

I am thinking attempting to parallel top balance 280ah cells could cause problems even if the charge leads are placed at each end of the pack. The poster was using a 6 amp power supply for balancing. Is it possible the cells in the middle didn't top up all the way? I honestly don't know but I am thinking it might be a better idea to charge each cell individually, then put them in series and connect the BMS no matter the size of the pack due to the size of these cells. Or use a power supply with a much higher current rating?

Anyways, problems started when he hooked up the Chargery BMS. Either he did not hook it up properly or he has two defective BMS's. I doubt it's the latter. I can not possibly conceive how the cell voltages changed that much on their own. The fact the one jumped as high as 3.9 volts with no charge applied is very odd. I don't understand how that is possible. And this was confirmed with the posters DMM.

All I am hoping for at this point is for the poster to come forward with more information or at least an update. There is no shame in admitting user error if that is the case here. I believe the poster could provide some very valuable input that would be beneficial.

I think that the most likely scenario is that for at least part of the process there were bad connection on some of the bus bars and maybe the balance leads ... but that doesn't explain how some of the cells went high since the Chargery doesn't have active balancing.

I ordered LifePo4 80AH cells from AliExpress before I saw Will's video warning about them. So I got scammed and with any luck they will get lost in the mail and I'll get a full refund. Since then, I have looked at several of them and found a few tell tale signs that indicate the seller is less than honest.

Markings - If there are no markings on the battery then its a repackage job. If someone is standing behind them, they will at least have their name on it.

Warranty - If the seller makes no mention of warranty, then its because its a used battery.

Returns Not Accepted - A guarantee that they don't have faith that you will be happy with the product.

Bigger - When the battery is physically bigger than other batteries of the same type and AH rating. When a defunct battery is taken out of service it may still test good for a lower AH rating.

Ambiguous AH rating - The cell is a 100AH battery, but the specs say it will produce "> 50AH".

I just wish I knew that stuff before I put my order in.