EVE matched cells, some cells drops very fast

[ArthurEld]

One more snarky comment.

If I paid for matched cells, I'd stay even farther from the knees because I wouldn't want to mess up my expensive cells.

I'm not trying to start anything Steve. I know a lot of people will probably buy those matched cells. I won't. No biggie

I think your thrashing and bashing your cells into shape makes those matched cells worth less too.

 

[Steve_S]

Given what's coming out of my test & abuse cycles, is Bottom to Top Balancing is more important with these than most of us thought.
Why it's taken four fairly rough "empties" (as in quite rude & hard high amp) to get the bottom to play nice is odd.
The hard charges have been done with a stagger. 1 pack, 2 packs, 4 packs and in sets because I have 280 & 175's so I have to adjust for kicking the 175's on their own... Pushing 150A into a 175 = not good eh. I don't mention the 175's much, as they are Used Cells that came out of that ShunBin frackas. They are also a different class of cell, from what I could find out (not easy) they came from EV's. Quite thin and really wide. They have their peculiar quirks.

I have always kept the Thrashing below the max recommended C-rates. None of the cells ever got hot, barely warm TBH, even when a single 280 Pack was getting 150A. I'm not going to risk that kinda change sitting on the rack.

Up until today, they pretty much capped at 26.4V a pack, since the last run and "just" before I started this next charge cycle, they had levelled and were sitting at 27.1 disconnected from systems, as I flipped to the FLA bank to allow them to settle on their own... I ended up letting them sit 1.5 hours. First time I saw them settle into that voltage across all packs.

BTW, I was also one of the first here, right after Mdav to get a batch of these 280's, they came in March, I suspect they may have been New Old Stock but there is no way to verify such.

As for AH/WH/SOC.... Well I am trying something tediously painful but seems I may have nipped that in the bud. I dunno yet, that will be determined during the next set of load tests. Even then I'm not sure because I am not doing per cell stuff now... These are all bound, boxed and not coming apart again. Way too much Blue Air Potentential doing that.

ONE DIFFERENCE FROM MOST...
The powerhouse is at 10C/50F temp. Packs are averaging 16C/60F while charging, but I have the Charger (my EVO 4024) dumping the heat towards the battery rack, so this is no surprise and expected. I can't say if temp is a factor given where it sits.

The EVO's can output 100A but you have to program it, default is 40A.

EDIT: Just went out and checked on them they are within 10mv and tickling 3.4 per cell.
They can now rest and just do duty, as I'm already 16 hours into my day.

 

[Factory400]

I took the 'get the cheapest cells you can find' route. Of course the vendor claims Grade A, matched, etc, etc. but they are probably not.

The were so low-cost that even if they were significantly less than advertised, the $/per unit energy is still pretty good and it gives me the chance to better understand how to best cope with mismatched cells. In my case, the 16 cells I have are closer to advertised spec than I would have expected. The risk was worth it this time.

50% more for matching does not add up for how I am using the batteries. 20%-80% the majority of the time at .5C charge/discharge or less. Is it worth paying for and driving your expectations up?

 

[Steve_S]

The TRANSLATION> Matched = They are matched for IR with a YR1030 or YR1035 at their storage voltage 3.0-3.2V as received from the factory.

 

[Dzl]

Do you consider cells that are tested at less than 280 amps Grade A cells? Personally I don't.

Cells that do not meet minimum rated capacity are by definition not grade A, by general industry standards and by EVE's own standards (for any application).

 

[ArthurEld]

Has anyone demanded replacements? Has anyone determined that people have gotten better cells in the past?
I have looked through a lot of posts and I don't remember seeing people claiming to get full capacity.
There's always been a lot of mystery about whether people are getting full capacity.

But when I see a bunch of people saying they got low capacity cells replaced I will jump on board.

I kind of get the impression that everybody wants China to stop making false claims and they keep telling new buyers to demand that they change. But I doubt very much we can change China.

Like I said, when I see 5 or 10 people claim "I got all my cells replaced that were under 280Ah" then, I'll jump on board and demand my cells be replaced. I'm not going to be the 1st person to make those demands just because somebody says "Those people in China should change''. And a bunch of people jump in and say "Ya, those people in China should change"

Will is the only one I have seen get his money back. His cells were more than 15% under capacity too.

 

[Gazoo]

Cells that do not meet minimum rated capacity are by definition not grade A, by general industry standards and by EVE's own standards (for any application).

I just finished a charge staying within the sweet spot of my battery which is between 25.35 and 27.25 volts. I pumped in 248.8ah's so that is the useable capacity of my battery....or very close to it.

To prepare I discharged the battery to 25.35 and there was an 8mv difference. Below that the delta starts going up. The BMS displayed 17.5ah's remaining.

When the voltage reached 27.25 volts I had a 22mv difference between the cells. Remember the total capacity of my battery is right at 272ah's.

So add 248.8 plus the 17.5ah's remaining and that equals 266.3ah's. Then add what I would have obtained by letting the cells charge until the BMS cuts off the highest cell and we are getting close to 272ah's. I realize my test will vary plus or minus a few ah's. But it gives me a good idea of what my actual usable capacity will be if I keep the battery at a 60 to 70% SOC.

 

[Gazoo]

Will is the only one I have seen get his money back. His cells were more than 15% under capacity too.

With regards to the EVE cells yes...I recall one member who was only getting 177ah's. As I recall it was @Capt Bill and he had his cell replaced. In my case, and I am sure many others it's not worth the hassle. I have 97% capacity. But that's because I have one weak cell although I did not capacity test them individually. I still feel I got a good value for what I paid. But I am not happy with Basen since we were told in the group buy one thing and then that ended up not to be true. Basen lied. Granted the cells are not capacity matched, but each cell should have been 280ah's. And we see some getting 265ah's. What's up with that?

I do think everyone needs to realize before ordering any more EVE cells, the chances are good that no one will get the full capacity from the battery. One might get the full capacity form a couple of cells, but not all of them. Lishens look more promising (so far) of at least matching their spec sheet capacity of 272ah's.

The point I was trying to make is that any cell advertised as grade A, and most of them are, should have at least the capacity of their spec sheet. And I think it's time to start calling out the suppliers that are not living up to what they are advertising. How to go about that is beyond me.

 

[ArthurEld]

I have a couple cells that appear to be about 272. I still haven't checked them all and it could be months before I get done. Or never.

It seems to me that if you want to get the best out of your cells you have to have spares. The spares will be the lowest capacity until a cell in use becomes lower then swap the lower one for a spare.

I think buying 5 spares (48V) is cheaper than buying all of the stuff and taking the TIME to check cell capacity accurately. Cheaper than buying matched cells too. I'm not sure matched cells would beat unmatched cells with spares for total Ah over life.

My opinions are often unpopular. ?

 

[ArthurEld]

With regards to the EVE cells yes...I recall one member who was only getting 177ah's. As I recall it was @Capt Bill and he had his cell replaced. In my case, and I am sure many others it's not worth the hassle. I have 97% capacity. But that's because I have one weak cell although I did not capacity test them individually. I still feel I got a good value for what I paid. But I am not happy with Basen since we were told in the group buy one thing and then that ended up not to be true. Basen lied. Granted the cells are not capacity matched, but each cell should have been 280ah's. And we see some getting 265ah's. What's up with that?

I do think everyone needs to realize before ordering any more EVE cells, the chances are good that no one will get the full capacity from the battery. One might get the full capacity form a couple of cells, but not all of them. Lishens look more promising (so far) of at least matching their spec sheet capacity of 272ah's.

The point I was trying to make is that any cell advertised as grade A, and most of them are, should have at least the capacity of their spec sheet. And I think it's time to start calling out the suppliers that are not living up to what they are advertising. How to go about that is beyond me.

Sounds like Capt Bill had a really bad cell and deserved a replacement. I have seen a few people demand a replacement for a cell that was destroyed by the buyers mistakes. And they got the replacement cell.

 

[Gazoo]

Sounds like Capt Bill had a really bad cell and deserved a replacement. I have seen a few people demand a replacement for a cell that was destroyed by the buyers mistakes. And they got the replacement cell.

Yeah I have too....but speaking for myself I take responsibility for my own actions.

 

[Sojourner1]

With regards to the EVE cells yes...I recall one member who was only getting 177ah's. As I recall it was @Capt Bill and he had his cell replaced. In my case, and I am sure many others it's not worth the hassle. I have 97% capacity. But that's because I have one weak cell although I did not capacity test them individually. I still feel I got a good value for what I paid. But I am not happy with Basen since we were told in the group buy one thing and then that ended up not to be true. Basen lied. Granted the cells are not capacity matched, but each cell should have been 280ah's. And we see some getting 265ah's. What's up with that?

I do think everyone needs to realize before ordering any more EVE cells, the chances are good that no one will get the full capacity from the battery. One might get the full capacity form a couple of cells, but not all of them. Lishens look more promising (so far) of at least matching their spec sheet capacity of 272ah's.

The point I was trying to make is that any cell advertised as grade A, and most of them are, should have at least the capacity of their spec sheet. And I think it's time to start calling out the suppliers that are not living up to what they are advertising. How to go about that is beyond me.

Or the other option is if buying these cells... realize you're getting "grade a" 265ah not 280ah. Call it China windage, similar to Kentucky windage on the range.

 

[snoobler]

I have a couple cells that appear to be about 272. I still haven't checked them all and it could be months before I get done. Or never.

It seems to me that if you want to get the best out of your cells you have to have spares. The spares will be the lowest capacity until a cell in use becomes lower then swap the lower one for a spare.

I think buying 5 spares (48V) is cheaper than buying all of the stuff and taking the TIME to check cell capacity accurately. Cheaper than buying matched cells too. I'm not sure matched cells would beat unmatched cells with spares for total Ah over life.

My opinions are often unpopular. ?

I'm with you. I bought a single spare for a 24V. Essentially, $80 extra to avoid the hassle if a single cell turns out to be a turd.

Still gonna test all of them...

 

[ArthurEld]

The cells get tested pretty good during the top balancing process. I learn which ones have the lowest capacity. And I know the capacity of my whole battery. That gives me a pretty good feel of what I've got.
Maybe after I get my system installed I will get around to testing every cell.

 

[snoobler]

The cells get tested pretty good during the top balancing process. I learn which ones have the lowest capacity. And I know the capacity of my whole battery. That gives me a pretty good feel of what I've got.
Maybe after I get my system installed I will get around to testing every cell.

IMHO, that's adequate. I have the luxury of having enough test equipment to simultaneously charge and discharge 12 cells at a time. I won't be top balancing. I'll be individually charging all cells to 3.65V.

 

[Capt Bill]

.I recall one member who was only getting 177ah's. As I recall it was @Capt Bill and he had his cell replaced.

Yes, I did get one below par 280Ah cell from Xuba on my 1st 8 cell order. I noticed it was below par via my Chargery BMS8T's info pages, most notable was on the individual cell volage graphic showing one cell emptying early. I added pictures of that and some other pages to kind of document my situation including how that one cell also showed more internal resistance than the others (notice that shifts around depending on amp flows). My initial testing of that Battery Pack was my using it to run my main house sub-panel without solar or grid input using maybe up to 80 -100 + amp battery bank draws, mixed with 20- 30 amp draws and much less to see how long these new LiFePO4 could last before needing me to charge them back up with my grid powered Charge option at about 120 amps IN. That 177 Ah was an estimate based on the Chargery information whose 300A shunt could have been better calibrated (which I have done since then ). I later tested that same defective below par cell on one of those 200 watt fan heater draw down units, and got a 226 Ah measurement (still noticably below par). That same particular cell also has shown me via later testing; it would not take a full battery charge to 3.6v or 3.65v; as my 10 amp bench power supply could only get it up to a 3.3v max. ... Glad Xuba replaced it after a my document efforts of the short.

... One other Lesson: I tried to mix in the new cell at close to same cell voltages, and charging up full set. That resulted in a new battery cell that at first glance looked worse than the one it replaced (it drained WAY early). One forum member asked me if I had top balanced (which I only did the first time). Top Balancing a 2nd time with the new cell made it act new, like my other good cells. I learned from others including Will P, plus my personal hands on: Top Balancing is very important. ... Got a second set of 8x EVE 280 Ahs on way, & expecting them by end of Dec to up my battery bank to 560Ah. I expect them to prove to be their full 280Ah, and now have a couple of ways to test em for that. Super Glad we have a way to compare notes on LiFePO4 quality control issues here. Still seems mostly like the best deals I have seen. :+)

 

[Solarfun4jim]

IMHO, that's adequate. I have the luxury of having enough test equipment to simultaneously charge and discharge 12 cells at a time. I won't be top balancing. I'll be individually charging all cells to 3.65V.

@snoobler
Lucky lucky you. Do you think charging all your cells to the same 3.65v individually, but at the same time/temp/conditions etc, will in theory at least, give you the perfect top balance equivalent?

This is interesting.

 

[snoobler]

"Perfect" has no place on this forum...

Should work close enough to a full parallel balance to be adequate, particularly when these cells are full at 3.65/14A current. I'll only be pushing 20, and the charge will taper to 2A before termination, so they should all be stuffed to the gills.

 

[Solarfun4jim]

"Perfect" has no place on this forum...

Should work close enough to a full parallel balance to be adequate, particularly when these cells are full at 3.65/14A current. I'll only be pushing 20, and the charge will taper to 2A before termination, so they should all be stuffed to the gills.

thanks

 

[Honuz]

"Perfect" has no place on this forum...

Should work close enough to a full parallel balance to be adequate, particularly when these cells are full at 3.65/14A current. I'll only be pushing 20, and the charge will taper to 2A before termination, so they should all be stuffed to the gills.

Hello all,
I will receive my cells (hopefully) in 2 weeks

1. I top balance them individually at 3.65v under 14A, let them rest for 2 days, check

2. I top balance them all 16 cells in parallel at 3.65v under 14A, let them rest for 2 days, check

In the second case cells will certainly stay a longer time at 3.65v cause, I suppose, most of us do not have tremendous chargers.
(I followed the discussion but I may have misunderstood some english expressions)

So, in the end...what is the the best way we have (with small charger, my Riden is on the way) to deal with this top balancing (which certainly already have been done at seller office, at least celle per cell)...…?

Thanks and sorry if this question as already been asked a zillion times, I kind did not find the clear answer (taking into account I do not understand English perfectly).

 

[Dzl]

I like the parallel step method outlined in the marinehowto article:

    Parallel Step-Method Top Balance:

    0- Verify cells are at similar SOC/voltage, prior to wiring them in parallel.
    1- Wire the cells in parallel
    2- Set the power supply to 3.40V and 80% or less of the rated amperage (80% to not burn it out)
    3- Turn on power supply and charge cells to 3.400V
    4- When current has dropped to 0.0A at 3.400V turn off the power supply & set it to 3.500V
    5- Turn on power supply and charge cells to 3.500V
    6- When current has dropped to 0.0A at 3.500V turn off the power supply & set to 3.600V
    7- Allow current to drop to 0.0A (or very close) at 3.60V
    8- Done, pack is balanced.

The advantages of doing it in steps are (1) less time spent at or near 3.65V, (2) makes it easy to be present and attentive during the last phase (3) gives you a few steps to catch a mistake.

I also suggest you read the great resources filterguy has put together on the topic of balancing
explanation-for-beginners-of-top-and-bottom-balance
top-balancing-lifepo4-cells-using-a-low-cost-benchtop-power-supply

 

[Honuz]

I like the parallel step method outlined in the marinehowto article:

    Parallel Step-Method Top Balance:

    0- Verify cells are at similar SOC/voltage, prior to wiring them in parallel.
    1- Wire the cells in parallel
    2- Set the power supply to 3.40V and 80% or less of the rated amperage (80% to not burn it out)
    3- Turn on power supply and charge cells to 3.400V
    4- When current has dropped to 0.0A at 3.400V turn off the power supply & set it to 3.500V
    5- Turn on power supply and charge cells to 3.500V
    6- When current has dropped to 0.0A at 3.500V turn off the power supply & set to 3.600V
    7- Allow current to drop to 0.0A (or very close) at 3.60V
    8- Done, pack is balanced.

The advantages of doing it in steps are (1) less time spent at or near 3.65V, (2) makes it easy to be present and attentive during the last phase (3) gives you a few steps to catch a mistake.

I also suggest you read the great resources filterguy has put together on the topic of balancing
explanation-for-beginners-of-top-and-bottom-balance
top-balancing-lifepo4-cells-using-a-low-cost-benchtop-power-supply

Those steps are a good idea...I wonder why I did not think of it....
Thanks for this method, I will use it. Thanks for the reading too..!

 

[RCinFLA]

I would be suspect of bus bar contact area. Using the small head screws with small diameter washers provided with cells only pressures the bus bar around the head of screw and small washer forcing much of the current though that contact area. Copper bus bars are quite pliable. If the bus bar gets warm it further takes a dimple set around the head of screw and small washer so it relieves much of the bus bar surface area pressure from the battery post surface.

Cleaning surface area with alchohol and using a strong stainless washer with diameter as wide as bus bar will help maintain pressure on the contact surface across the whole bus bar to battery terminal interface. Just be careful the washer thickness and screw length doesn't leave too little thread penetration into battery terminal making stripping battery post threads more likely.

 

[Gazoo]

Hello all,
I will receive my cells (hopefully) in 2 weeks

1. I top balance them individually at 3.65v under 14A, let them rest for 2 days, check

2. I top balance them all 16 cells in parallel at 3.65v under 14A, let them rest for 2 days, check

In the second case cells will certainly stay a longer time at 3.65v cause, I suppose, most of us do not have tremendous chargers.
(I followed the discussion but I may have misunderstood some english expressions)

So, in the end...what is the the best way we have (with small charger, my Riden is on the way) to deal with this top balancing (which certainly already have been done at seller office, at least celle per cell)...…?

Thanks and sorry if this question as already been asked a zillion times, I kind did not find the clear answer (taking into account I do not understand English perfectly).

So which Riden did you order? Did you order the complete kit with the power supply? The 12 or 18 amp one? If you ordered the one that comes with the power supply you can safely run it at it's full output. The 18 amp version only draws 65 watts and the 12 amp version only draws 44 watts from the power supply running it's full output at 3.65 volts.

The Riden has a battery charging feature, and over voltage and over current protection, so you can skip the step method if you are comfortable doing so. I started to do the step method myself but the current kept dropping too much and it gets to be very time consuming. I was confident enough to sleep while it was charging. I was happy I was awake when it reached the end of charge so I could make sure it would shut down. It did. But I had the OVP set I think at 3.7 volts just in case.

The Riden comes with fork terminals. I used those for connecting to the Riden and made 12awg cables and put ring terminals on the other end for connecting to the cells. You want good connections. Following is what I did using the Riden:

1- Verify cells are at similar voltage, prior to wiring them in parallel.
2- Wire the cells in parallel
3- Set the Riden to 3.65V and it's full output current. Note: I used the full 12 amps of my Riden and it didn't burn out. It's not going to because the 3.65 voltage is so low.
4- Turn on power supply and charge cells to 3.65V
5- When current has dropped to 90ma's the Riden will cut power to the cells and stop charging.
6- Done, pack is balanced.

You can connect the Riden to the cells, turn it on and set the voltage. It has a button to start power going to the load. It has a separate button on the front to turn it on and off. And it has a switch on the back to power on/off the power supply.

I do believe the step method is a very good idea if using a traditional power supply mainly to avoid overcharging the cells. Once they reach 3.4 volts the voltage will start to rise quickly.

Following are some notes I took while I was parallel top balancing my 8 cells with the Riden:

----------------------------------
Started charging on 10-30-2020 at 7:45PM. During this time I tried the step method and decided to skip it. Due to the low voltage there wasn't enough current going into the cells and I set the Riden to 3.65 volts to get the full 12 amps.

11-4-2020 9:14 PM. Charger switched to CV at 3.60 volts but still charging at 11.98 amps. The voltage at the cell terminals was 3.391 volts. Voltage at cell terminals when charger displayed 3.65 volts was 3.443 but it did go into absorb mode. Current on the display is 1300ah's and wattage is 4595wh's.

11-5-2020 1:10AM. The voltage on the Riden display was fluctuating between 3.64 volts and 3.65 volts. The voltage on the cells is 3.65 volts and occasionally I got a reading of 3.651 volts. The current on the display at the tail end was fluctuating between 210ma's and 120ma's and acted that way for awhile. Finally when I noticed the current drop to 90ma's the charger cut off. The current going into the cells as measured by the Riden was 1305.59 amps and the wattage was 4613.86.
----------------------------------

The only bad thing about the Riden I have found is it's cut off current. The manual states the Riden will cut off when the current has reached 100 ma's. It has been suggested to Riden to make that adjustable.

Also the Riden switches to CV about .5 volts lower than what the charging voltage is set to. This doesn't effect anything. Other than that I love it!

 

[HighVolt]

Do you consider cells that are tested at less than 280 amps Grade A cells? Personally I don't.

Amy arranged for my EVE cells to be tested prior shipping. She said they sent 20 to the battery testing factory and shipped me the best 16. I received the16 capacity reports and the capacity was labeled on the cells in WH. The lowest was 278,635 and the highest 281,264. Most are high 279 and 280. I placed a sample test report in the Resources. Cost was US $4 a cell. Technically some of these cells don't meet spec but I am pretty happy at the price as long as my own testing confirms after a top balance.