Senbury LiFepo4 cells 280ah

[SBR]

Thank you for your support. Please contact me if you still need to buy.
I plan to hold a discount activity. The price of ETC277Ah is very good now. If you buy 16pcs, the price is 69 dollars; if you buy more than 48pcs, the price is 68 dollars

 

[SBR]

Now top balancing them as per @Will Prowse video using my super duper new power supply.
View attachment 21178

View attachment 21179

If you have any questions, you can contact me at any time. I will keep in touch with you
I wish you a happy life

 

[Dzl]

Thank you for your support. Please contact me if you still need to buy.
I plan to hold a discount activity. The price of ETC277Ah is very good now. If you buy 16pcs, the price is 69 dollars; if you buy more than 48pcs, the price is 68 dollars

Thank you sir! That is a very competitive price. I am happy to see that a few forum members recently received orders from Senberry, it looks like good quality so far. Once they complete initial tests, I think there will be more interest.

Do you have datasheets available for CATL or ETC (CATL 200 Ah and ETC 277 Ah). You can private message me if you prefer.

 

[SBR]

Thank you sir! That is a very competitive price. I am happy to see that a few forum members recently received orders from Senberry, it looks like good quality so far. Once they complete initial tests, I think there will be more interest.

Do you have datasheets available for CATL or ETC (CATL 200 Ah and ETC 277 Ah). You can private message me if you prefer.

Ok, I'd love to chat with you. I sent you a message

 

[shavermcspud]

Unfortunately my luck has changed somewhat with these cells.
I did the top Ballance to 3.65v, assembled in to a 16s pack and did a capacity test, this went well and I recharged and put in to service with a charge profile that was from 20%-90% end voltage of 57v . I have been away for the last few days so left the batteries to charge up with my PV, i came home last night and the cell voltages were all over the place, from 2.9v for the lowest to 3.8v for the highest according to my chargery BMS, the pack has gone through two cycles while away and has delivered according to my inverter 12.9kW overnight per night. I'm not sure what's going on here with mine. Ive doubled checked all connections, bus bars etc and they seem fine. the IR of the cells seems to be quite different but im led to believe I can trust the built in IR measurement of the chargery

 

[Dzl]

Unfortunately my luck has changed somewhat with these cells.
I did the top Ballance to 3.65v, assembled in to a 16s pack and did a capacity test, this went well and I recharged and put in to service with a charge profile that was from 20%-90% end voltage of 57v . I have been away for the last few days so left the batteries to charge up with my PV, i came home last night and the cell voltages were all over the place, from 2.9v for the lowest to 3.8v for the highest according to my chargery BMS, the pack has gone through two cycles while away and has delivered according to my inverter 12.9kW overnight per night. I'm not sure what's going on here with mine. Ive doubled checked all connections, bus bars etc and they seem fine. the IR of the cells seems to be quite different but im led to believe I can trust the built in IR measurement of the chargery

Hmm that's not good. I hope you can get this resolved/figured out.

You have checked the cell voltages with a multimeter to verify what you are seeing on the chargery?

Everything seemed normal during the capacity test and the cells discharged at similar rate? Was the Chargery hooked up at this point?

I don't have any experience here, but I don't understand how during normal charge/discharge cycles one cell could become overcharged while another cell in the same pack is almost empty. Especially just two cycles after an observed normal charge/discharge cycle.

Something screwy is going on.

 

[Gazoo]

You said you got 286ah when you tested the pack...that was a 48 volt pack right? But you received 32 cells? How did you configure your pack?

As for the rest I have no clue. I don't know anything about the Chargery. I would be very surprised if there is a problem with the cells.

 

[Denis]

Unfortunately my luck has changed somewhat with these cells.
I did the top Ballance to 3.65v, assembled in to a 16s pack and did a capacity test, this went well and I recharged and put in to service with a charge profile that was from 20%-90% end voltage of 57v . I have been away for the last few days so left the batteries to charge up with my PV, i came home last night and the cell voltages were all over the place, from 2.9v for the lowest to 3.8v for the highest according to my chargery BMS, the pack has gone through two cycles while away and has delivered according to my inverter 12.9kW overnight per night. I'm not sure what's going on here with mine. Ive doubled checked all connections, bus bars etc and they seem fine. the IR of the cells seems to be quite different but im led to believe I can trust the built in IR measurement of the chargery

I have two banks of 16 cells parallel 280ah without a bms, but I did add an active balancer on each bank that I can monitor with my phone.
Since adding the balancer I've noticed that not all cells are equal in some form or another.
Capacity, resistance and chemical reactions within are not all the same for each cells.
All my cells are grade A, to a point, but not all cells are.
They vary in voltage while being charged, I've noticed up to .150v or 150mv, and my cells are balanced.
With that kind of fluctuations between cells, a bms would always be triggered.
I control charge bulk at 56.8 volts, and this one cell has reached 3.62v while the others are around 3.53v and some a bit lower.
And as soon that I apply a heavy load on the bank, that same cell is at the lowest of the bank.
You might have a similar situation, your bulk voltage should be lowered to 56v I think, just to protect your bms and system.
I included a picture of my cells monitor reaching full charge while writing this.

 

[Denis]

This is a picture taken just about 17 minutes later with a load of 600 watts only. You can see my point that cell #16 is now the lowest, and if I apply a good load it would go down really fast to maybe .050 v lower than the rest.

 

[shavermcspud]

You said you got 286ah when you tested the pack...that was a 48 volt pack right? But you received 32 cells? How did you configure your pack?

As for the rest I have no clue. I don't know anything about the Chargery. I would be very surprised if there is a problem with the cells.

im doing them 2 packs at a time, testing them and then will put the full 32 in 16s2p. currently working on on 16s pack.

i have 2x bms16t one for each 16s pack.

 

[shavermcspud]

so here is the problem, although it measure exactly the same voltage as the rest of the pack at 3.35v its hugely bloated and rounded. i presume this cell knackered. I've checked the chargery log and no cell has gone above 3.8v on a charge cycle so confused unless my bms is also shot

Its so bloated the bus bars wont even reach across now, once i undone the clamp system holding them together it sprung apart from the adjacent cell. the other 31 cells are all ok and both packs have gone through two cycles.

 

[Gazoo]

This is a picture taken just about 17 minutes later with a load of 600 watts only. You can see my point that cell #16 is now the lowest, and if I apply a good load it would go down really fast to maybe .050 v lower than the rest. View attachment 21762

Thanks for sharing. I noticed in the other thread you top balanced the cells individually. I wonder if there is a difference between using that method and parallel top balancing. Also could you post the link to the active balancer you are currently using? Thanks.

 

[Dzl]

Thanks for sharing. I noticed in the other thread you top balanced the cells individually. I wonder if there is a difference between using that method and parallel top balancing. Also could you post the link to the active balancer you are currently using? Thanks.

I don't know, or have any facts to back up my impression, but intuitively I've always felt it made more sense to parallel balance.

so here is the problem, although it measure exactly the same voltage as the rest of the pack at 3.35v its hugely bloated and rounded. i presume this cell knackered. I've checked the chargery log and no cell has gone above 3.8v on a charge cycle so confused unless my bms is also shot

Its so bloated the bus bars wont even reach across now, once i undone the clamp system holding them together it sprung apart from the adjacent cell. the other 31 cells are all ok and both packs have gone through two cycles.

It does seem like that may be a bad cell. But I'm having trouble following along here. You said it measures 3.35V, along with the rest of the pack, earlier you said one of your cells was at 3.8v and another at 2.9v, were these readings inaccurate?

 

[MisterSandals]

Yea, maybe a bad cell. But...

I cannot help but wonder if charging all the cells, 16 cells in parallel for 15 hours, applying the charge to a single end of the parallel bank had any bearing on this. It would be interesting to know if the bad cell was positioned on either of the ends. I do not see any cell labels so I am guessing there are not any notes at the cell level for the top balancing and battery build.

There might have been something to learn as a collective from this, or maybe just a bad cell. We may never know.

 

[Dzl]

I'm curious whether you are any closer to finding out how this could occur:

i came home last night and the cell voltages were all over the place, from 2.9v for the lowest to 3.8v for the highest according to my chargery BMS

And whether these voltages have been confirmed with a multimeter?
What were the voltage limits set to on the chargery?

And curious what you mean by this:

I'm not sure what's going on here with mine. Ive doubled checked all connections, bus bars etc and they seem fine. the IR of the cells seems to be quite different but im led to believe I can trust the built in IR measurement of the chargery

Are you saying IR between cells is quite different? or the IR is different than initially measured during testing?

For reference, I recently noticed that Steve, One of the bigger proponents of the EVE cells and one of the better known resellers in particular, cautions/clarifies that:

The EVE 280 and other similar cells selling for the lower prices such as $80 per 280 cell are Voltage Matched, within "factory specs" for IR at test voltages but these are not fully "matched" up cells. That is a rather more involved process which cycles the individual cells through charge/discharge while validating the various IR readings through the cycles, at which point cells are sorted/categorised by their values and those that fall outside of spec (over or under) hit reject.

They are NOT fully Voltage & IR Matched, they are within the "Grade-A" spec though. You'd day 2x to 3x more for matched cell bundles. You do want to run these in straight series. Some have had luck and others have not but you are forewarned.

I have found that with these EVE 280's which are Grade A & Voltage Matched (not Internal Resistance Matched) they do tend to meander, meaning the cells will diverge and have volage differentials. This is most pronounced above 3.5V per cell. or during Heavy charge/discharge and passive balancing can't keep up to that. On "average" 1 millivolt per AmpHour capacity seems to be the norm. I have not done Active, only Passive balancing, and am now getting into the Active Balancing of my packs.

That said, I shouldn't think that moderate differences in IR could lead to the extreme divergence in voltage you noted, or the bulging at normal SOC. For me at least, there are way too few details of your situation to make meaningful speculations.

 

[Gazoo]

Yea, maybe a bad cell. But...

I cannot help but wonder if charging all the cells, 16 cells in parallel for 15 hours, applying the charge to a single end of the parallel bank had any bearing on this. It would be interesting to know if the bad cell was positioned on either of the ends. I do not see any cell labels so I am guessing there are not any notes at the cell level for the top balancing and battery build.

There might have been something to learn as a collective from this, or maybe just a bad cell. We may never know.

Someone else posted the cells on the other end from the charge cables did not charge at all. I read that post today so it's recent but unfortunately can't find it and don't recall all the details. I agree it would be nice to know where the bad cell was positioned. I definitely will label mine when I receive them. And put the cables on the opposite ends of the pack.

 

[Gazoo]

That said, I shouldn't think that moderate differences in IR could lead to the extreme divergence in voltage you noted, or the bulging at normal SOC. For me at least, there are way too few details of your situation to make meaningful speculations.

There is more pertinent info in this thread:

Battery IR for new cells

Ive started construction of my 16s2p 280ah LFP pack. I have balanced them as per Wills video at 3.65v until the current dropped off to near zero. All cell voltages are the same on the chargery BMS but I have a concern over the IR Is this within spec for new cells under a 9amp load?

diysolarforum.com

I don't believe the IR measurements on the Chargery are accurate.

As you said more information is needed before we know what happened here, especially concerning the bloated cell.

 

[Luthj]

Have you confirmed that the high and low voltage disconnects were functioning and set to correct levels? Its not unusual for BMS to ship with these functions disabled or set incorrectly. I am assuming you have the a NO disconnect relay wired to the chargery relay control?

 

[MisterSandals]

I definitely will label mine when I receive them.

I recommend using letters like A, B, C ... because it gets confusing when you write notes about cell numbers referring to their position in the battery.

Also, labeling before unpacking can retain a little more data of that grouping.

 

[Gazoo]

I recommend using letters like A, B, C ... because it gets confusing when you write notes about cell numbers referring to their position in the battery.

Also, labeling before unpacking can retain a little more data of that grouping.

Actually I didn't think of that. I will use letters. I have 8 cells coming and I think I can still remember that part of the alphabet..