EVE LF280K possible problems?

[DWalker]

I think what Dexter is saying is that with that Trimetric shunt in place, the BMV-712 is going to be off when it's reporting information.

Yes, it is off. It'll be changed down the road.

"2; Total bank voltage and cells mixed up, read 3.3-3.4---3.6 and 4.1 cell voltage."
Are you sure it is 4.1V? max is 3.65V, if you go above that you will damage the cell. Are you using Multimeter to read each cell Voltage?

Are you sure it is 21milliohm not 0.21 milliohm? Look at the sticker on the battery or show us the sticker on the battery. 21miiliohm is really bad.

Bud..., do you see a (dot) in front of the millohm numbers on the tape on top of the cells , or is it just visible on my end?

 

[Bud Martin]

Yes, it is off. It'll be changed down the road.

Bud..., do you see a (dot) in front of the millohm numbers on the tape on top of the cells , or is it just visible on my end?

I saw the tape with numbers with dot in front but your text referring to without the dot.
post #1: 'I see 38, 38, 39, 42 and 62, 64, 65, 67 milliohm, the last 4 seems very high considering the specs. sheet show 19 milliohm?'
The sheet probably shows 0.19 milliohm.
I.E.: My 230Ah DOCAN has 0.23 milliohm

 

[DWalker]

I saw the tape with numbers with dot in front but your text referring to without the dot.
post #1: 'I see 38, 38, 39, 42 and 62, 64, 65, 67 milliohm, the last 4 seems very high considering the specs. sheet show 19 milliohm?'
The sheet probably shows 0.19 milliohm.
I.E.: My 230Ah DOCAN has 0.23 milliohm

View attachment 133988

Mine shows .19. Whatever, I think they just stamp whatever sounds good at the time.

 

[DWalker]

Edited to hopefully make more sense.

Hello everyone. I’ve been reading many various posts on here for a few months in trying to learn about building and maintaining Lifepo4 battery cells but this is my first post about anything.
Last October 2022, I bought 8 ‘Eve LF280K’ supposedly A grade (-doubtful?) from ‘Amy Zheng’ at Docan Power. The transaction went well with fast shipping and fast email replies.
I did a good top balance on the cells and configured them as 12V 2P-4S configuration installing them inside an insulated box in my 5th wheel RV using one 200A JBD bms. Prior to the LF280K cells, I’d been using Trojan T-105’s for the last 7 years.
I’m having some problems now after 2 charges with the new 280 cells that I’d like to get some thoughts on from anyone that may be some help in figuring out what’s going on.
The first full charge was up to 14.2 volts, then absorb for two hrs. using a Victron IP22 charger, then I discharged to 10.6V then back to about a 60% SOC to sit. (FWIW, the batteries are in a box in the RV which is stored inside my shop and the battery bank is a constant 55-60 degs. F day and night).
A few weeks after that first full charge, I decided to do another charge on the bank for the heck of it and noticed a high mv spread starting at mid 13 volts. The spread went up to 326mv at 14.0 total bank volts. I stopped the charge there because it was increasing fast and I could see that it was going to hit the HVD so just stopped it.
Stopping the charge at bank voltage of 14.0-14.1V, #1 and #3 cells were low in voltage, just over 3.0V. #2 was roughly 3.6 and #4 was up to about 3.41-3.42V when stopped. It was definitely heading for HVD showing 326mv and moving up fast. I had the balancing set to start at 3.42V but there’s obviously no way it could possibly do anything as fast as the spread was climbing and as big as it was.
I moved some cells around in the bank a couple times and tried charging again but now I get a HVD (set at 13.6V) on cell #4 before the other cells get barely over 3V. I moved the charged voltage down to 13.8V but am having the same problem and it gets worse each attempt.
I’ve changed charger current between 15A and 30A on the IP22 and 18A from solar panels mounted outside the shop but of course all have same results.
I bought an internal resistance tester and checked the cells yesterday, I see 38, 38, 39, 42 and 62, 64, 65, 67 milliohm, the last 4 seems very high considering the specs. sheet show 19 milliohm?
I’m currently doing another top balance now using the 4 lower ir cells to then try using those 4 in a 4s configuration to see what happens, then do the same with the 4 high ir cells.
I’ve sent an email to Amy at Docan Power but I’ve got no response of any kind. I’m thinking since I’m not buying now but asking about a possible problem, I most likely won’t get a response. -I apologize for the length of this.
Any thoughts on what’s happening here?

Thanks, D. Walker

Aside from the typos and confusing pictures... I finished the top balance a

Edited to hopefully make more sense.

Hello everyone. I’ve been reading many various posts on here for a few months in trying to learn about building and maintaining Lifepo4 battery cells but this is my first post about anything.
Last October 2022, I bought 8 ‘Eve LF280K’ supposedly A grade (-doubtful?) from ‘Amy Zheng’ at Docan Power. The transaction went well with fast shipping and fast email replies.
I did a good top balance on the cells and configured them as 12V 2P-4S configuration installing them inside an insulated box in my 5th wheel RV using one 200A JBD bms. Prior to the LF280K cells, I’d been using Trojan T-105’s for the last 7 years.
I’m having some problems now after 2 charges with the new 280 cells that I’d like to get some thoughts on from anyone that may be some help in figuring out what’s going on.
The first full charge was up to 14.2 volts, then absorb for two hrs. using a Victron IP22 charger, then I discharged to 10.6V then back to about a 60% SOC to sit. (FWIW, the batteries are in a box in the RV which is stored inside my shop and the battery bank is a constant 55-60 degs. F day and night).
A few weeks after that first full charge, I decided to do another charge on the bank for the heck of it and noticed a high mv spread starting at mid 13 volts. The spread went up to 326mv at 14.0 total bank volts. I stopped the charge there because it was increasing fast and I could see that it was going to hit the HVD so just stopped it.
Stopping the charge at bank voltage of 14.0-14.1V, #1 and #3 cells were low in voltage, just over 3.0V. #2 was roughly 3.6 and #4 was up to about 3.41-3.42V when stopped. It was definitely heading for HVD showing 326mv and moving up fast. I had the balancing set to start at 3.42V but there’s obviously no way it could possibly do anything as fast as the spread was climbing and as big as it was.
I moved some cells around in the bank a couple times and tried charging again but now I get a HVD (set at 13.6V) on cell #4 before the other cells get barely over 3V. I moved the charged voltage down to 13.8V but am having the same problem and it gets worse each attempt.
I’ve changed charger current between 15A and 30A on the IP22 and 18A from solar panels mounted outside the shop but of course all have same results.
I bought an internal resistance tester and checked the cells yesterday, I see 38, 38, 39, 42 and 62, 64, 65, 67 milliohm, the last 4 seems very high considering the specs. sheet show 19 milliohm?
I’m currently doing another top balance now using the 4 lower ir cells to then try using those 4 in a 4s configuration to see what happens, then do the same with the 4 high ir cells.
I’ve sent an email to Amy at Docan Power but I’ve got no response of any kind. I’m thinking since I’m not buying now but asking about a possible problem, I most likely won’t get a response. -I apologize for the length of this.
Any thoughts on what’s happening here?

Thanks, D. Walker

Aside from the original and confusing post..., I finished the new top balance (of the 4 cells with the lowest IR) and installed them temporary in the RV battery compartment as a simple 12V 4S situation this late morning. I then discharged them to 10.6V, then recharged to currently 13.60V for the bank.
They just finished at 100% with only .008 spread.
Again, this is just using a simple 12V, 4S, 280A configuration, but still encouraging compared to what I've been seeing with the full 560 ah, 2P/4S original setup that I had problems with.
Actually, the BMS now shows 14.22V (bank voltage) I'm not concerned because it's now in absorb?
Tomorrow AM, the second batch of 4 cells that showed the high IR will be finished top balancing and I'll start this process all over again with those 4 cells.
I'm now curious what the second batch of 4 w/the high IR will do.
If they pass OK, then comes the scary part of reconfiguring all 8 again as 2P/4S.
This all so far sounds to me like they weren't fully top balanced properly the first time. I'd maybe agree with that but NOT the second time around. They were very well and completely top balanced the second time I did it to 3.6/cell.
Thanks for the various thoughts so far.

D. Walker

 

[HRTKD]

I then discharged them to 10.6V, then recharged to currently 13.60V for the bank.

I wouldn't take my EVE cells down that low. See this thread that shows a voltage chart for LiFePO4 and discusses healthy ranges.

LiFePO4 Voltage Chart?

Hi guys, I was looking through the mobile-solarpower.com website, and on this page I found a battery voltage chart for LiFePO4 batteries. But I noticed it wasn't showing the exact voltage ranges that my battery data sheet does. My data sheet shows 100% charge at 14.6V and 0% charge at 10.0V...

diysolarforum.com

 

[Docan AmyZheng]

( I am not sure if can reply here, as the forum has new rules for vendors)

Docanpower sticker printed value for voltage and internal resistance just for shipped out value from Docan China warehouse(it is not means will be same as battery specification）, that value will change via battery using

I also replied your email just now, sorry for the delay reply

 

[DWalker]

Well then welcome to the 280K is a dud club... anyway I would say get this attach and just leave it:

https://www.amazon.com/Cywhrvzsf-Equalizer-Balancer-Equalization-Capacitor/dp/B09G74WDN5/r

I could go on and and on about the 280K but at this point its? a ?...

So I had to use the 8s versions of these in my old xuba 280N and basen pack other wise they would drift around, some people say NOO you don't need them but I'm telling you it was the only thing that kept them in balance otherwise I would need to rip apart my pack and manually re-balance.

The only ones that did not need this were grade A cells form Luyuan that came with the test report. Those were just well behaving cells that did not give me any problems.

I have another active balancer coming that's spos'd. to be here tomorrow. It's a 5A 'Hankzor' that Andy (Off Grid Garage) tested. It apparently worked OK in his tests. I'll give it a try, maybe under normal charging it might be OK but really..., under normal charging/circumstances the passive balancer in the BMS should be OK.
There's no balancer that could have kept up with the major mv spread I was seeing, it was raising about 5mv every 8-10 seconds.
Anyway, I'll have it to play with once I get everything re-situated.
IMO, the Heltec one I had/have is a total waste of $ and time, it did absolutely nothing that I could measure. It was completely dead.

 

[HRTKD]

under normal charging/circumstances the passive balancer in the BMS should be OK.

Yep. My eight cells (4s2p) are almost perfectly balanced after 2+ years. My Overkill Solar BMS reports a cell voltage differential that is usually .010 or less.

 

[DWalker]

Yep. My eight cells (4s2p) are almost perfectly balanced after 2+ years. My Overkill Solar BMS reports a cell voltage differential that is usually .010 or less.

That's great! Sounds like the way it should be expected to be.

 

[cinergi]

Am I correct to assume that you have 8 cells in a 12.8v nominal configuration with one BMS so 2p4s? If so, it's crucial that the parallel connections are excellent and aren't subjected to movement (e.g. space between cells or a flexible busbar). It's very easy to cause imbalance if the parallel pairs of cells aren't perfectly connected to each other. That means cleaning the terminal and busbars etc just prior to connecting. (I have a 2p16s setup and had problems until I got flexible busbars in place. Even then, I'll hit 150mv of deviation at the top if it's been a while since the BMS has had a chance to balance them (in other words, hasn't sat at 100% for a while).

Edit: if the cells are indeed that far apart on IR, group the cells by IR when connecting in parallel.

 

[DWalker]

Am I correct to assume that you have 8 cells in a 12.8v nominal configuration with one BMS so 2p4s? If so, it's crucial that the parallel connections are excellent and aren't subjected to movement (e.g. space between cells or a flexible busbar). It's very easy to cause imbalance if the parallel pairs of cells aren't perfectly connected to each other. That means cleaning the terminal and busbars etc just prior to connecting. (I have a 2p16s setup and had problems until I got flexible busbars in place. Even then, I'll hit 150mv of deviation at the top if it's been a while since the BMS has had a chance to balance them (in other words, hasn't sat at 100% for a while).

Edit: if the cells are indeed that far apart on IR, group the cells by IR when connecting in parallel.

Thanks for that info. Yes, 2P4S is how I had and will have the final configuration once again.

After top balancing 4 yesterday and putting them in the tr. as a 4s set and charged up for a test to see how things went, the bank charged w/out a problem up to 14.2V. I let it go through a 1 hr. absorb. and it finished everything showing only a .008mv spread.
The other 4 are about done with a new top balance now and I'll do the same test w/them as 4s.
Then will pay close attention in reinstalling everything back into the 2P4S config. and see what happens from there.
I plan on cleaning the buss bars and terminals good again w/more No-Ox on the terminals as well.

The cells, when in place as a 2P4S assy. are snugly clamped in an insulated box w/plastic in between cells (photo). I don't think they will have any movement but I haven't had the tr. out of the shop yet since installing these, still winter. It's possible to have a tiny bit when the tr. is in motion I guess? I do have some flexible buss bars but they're a tad too short to use after everything's in place in the box.

 

[HRTKD]

If your compression fixture is doing its job, the cells won't move. Mine are in a compression fixture that uses four rods. I've had no problems with the solid bus bars on mine. However, I'm 4s, so my four rods have less weight to handle.

 

[DWalker]

If your compression fixture is doing its job, the cells won't move. Mine are in a compression fixture that uses four rods. I've had no problems with the solid bus bars on mine. However, I'm 4s, so my four rods have less weight to handle.

Right, I guess I'll find out abt. the movement. Might should put a third rod on each side while it's accessible.

Abt. taking the cells to 10.6? I had the impression that after top balancing to then do a full discharge to 2.5V per cell. Then charge up again a ways to get off the bottom. Might be wrong to have done that, my reasoning to use 10.6V (2.65V) per cell just sounded like a little less stress on the cells than down to 2.5/cell.

 

[HRTKD]

I didn't take my cells down after they were put in the trailer, or at all. Mine have yet to go below 30%, and that was to stress test the rest of the system, not the batteries.