Do you remember your charging parameters and can list them ??My 16 cells 200Ah sinopoly are different,
All cells aged differently.
The worst cell only has 115Ah.
Removing it from the pack and stick with 15 remaining cells......
Until I noticed the second worst cell only has 140Ah while the rest have 160-165Ah......out of the 200Ah specification....so, there is that....
Cells were installed back in year 2019 with SPF5000ES (replaced with SPF6000ES now), when installed at the time, those cells had 185-190Ah......
DIY battery longevity
- Thread starter Subdood
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Was using Daly BMS when it was just released back in year 2019.
Charging to 54.4v (3.4v each), floated to 53.6v and switched to grid at 48v (3.0v each).
OVP set at 3.60v and UVP at 2.7V. The pack was working well until year 2021 using SUOER (https://www.chinasuoer.com/hybrid-inverter/) off grid inverter until I noticed the one of the cell is causing the inverter to shut off early due to UVP. I switched to SPF5000ES in year 2022. (Now SPF6000ES with JK inverter BMS)
Top balanced battery pack with active balancer manually activated at upper knee back then.
Due to my limited solar panels, my max charging current is 62Amp max and mostly average around 35 - 45Amp.
Here JKBMS in action when using those 16 cells few weeks ago.
Top balanced to 3.45v for all cells.
Cell no 14.........ouch, triggered UVP and shut off the inverter.......meanwhile cell no 4 will drop later since it has 140Ah..........
Oh, ignore the cycle count, there was JKBMS firmware bug back then which was fixed with latest firmware.
If you take a look on the cycle capacity at JKBMS, 304.4 - 181.5 = 122.9AH ---> The effective capacity I have with one weakest cell for time being, but this is very dependent on load level. If the load is high, JKBMS will trigger UVP immediately. With low load around 150 - 200watt, it could reach 122.9Ah, but 400 -500 watts load will cause UVP with effective capacity of 115AH.
51.2V X 123AH = 6297.6 Wh for 16cells
vs
48v x 140AH = 6720 Wh for 15 cells.
Not much difference.....so I just keep all 16 cells to reduce amperage......
TomC4306
Solar Obsessive
At 3.4 volts per cell I don't think they were getting fully charged.
Try charging above 3.45 per cell and hold it there for 2 hours and then do your capacity test.
timselectric
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Or getting any useful balancing.
scubadoo
New Member
To add to my previous post re our 10 year old 4 cell 300Ah Sinopoly battery.Cycle counts for partial daily draws? I have serious doubts about accurate counting via any method.
Our battery is now approaching 3800 days of supplying somewhere in the region of 115Ah or 1.5 KWh overnight while the sun does not shine.
Someone else is welcome to perform any cycle maths.
Our 4 cell 300Ah Sinopoly LiFePO4 battery pack has now survived 10 years of full time travel both powering the motorhome and starting the 3.9l turbo diesel engine often multiple times a day.
I perform an annual C/10 capacity test each November. Converted to Ah the capacity has reduced from the original 315 to just 299. I expect a few more years of usable life.
No charge source exceeds 14.1V at which point the battery is always at 100% SOC regardless of charging current. Absorption time has proved unnecessary but continues while driving.
Increasing the battery terminal voltage to 14.50V at 30A takes less than a minute and obviously adds no usefully extra capacity.
c80A direct charging from the 100A rated Canter truck alternator (no smoke yet), 800W solar and rarely used Victron 30A mains battery charger.
No usual BMS installed due to the peak >700A engine start current. Our "BMS" consists of 20% SOC loud alarm, 10% SOC, 12.8V and 14.5V disconnects. Never triggered.
Since the original careful top balance cell balancing has proved unnecessary. I do check and tinker occasionally.
I recently paralleled a 4 cell 280Ah EVE battery pack again with no inbuilt BMS.
A recent push to 14.5V
Click to enlarge
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Nope, done that. If you take a look on my screenshot, it is top balanced at 3.45v each cells and floated at 3.45v for entire afternoon till evening.
The result next day speaks for itself.
I have NEEY 10A active balancer after all.....before it kicked the bucket and Hanzkor keeps on asking me to test the cable/batteries/crimp even though it is clear as day the balancer is faulty after less than 2 months of usage.
Only start balancing at 3.45v using it. Guess I will never get a working replacement.Done that.
Doesn't work either, no hope for cell 14.
Brucey
Solar Wizard
Ready and waiting at the bottom.
timselectric
If I can do it, you can do it.
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You can't balance at 3.45v. That's where balancing should start. (Not finish)Nope, done that. If you take a look on my screenshot, it is top balanced at 3.45v each cells and floated at 3.45v for entire afternoon till evening.
The result next day speaks for itself.
I have NEEY 10A active balancer after all.....before it kicked the bucket and Hanzkor keeps on asking me to test the cable/batteries/crimp even though it is clear as day the balancer is faulty after less than 2 months of usage.
Done that.
Doesn't work either, no hope for cell 14.
You are just at the top of the flat part of the charging curve.
Get the cells up to at least 3.5v and leave them there until they balance.
Assuming that you have an active balancer. If not, then it will take a month. (If at all) So, don't bother.
I did balanced it up to 3.6V for all cells before this too, with deviation of 0.010mv. No luck on cell 14 either. Which is why I lowered it down. Just my luck I guess?
Hopefully I can receive new EVE cells (18 cells) from Seplos after Lunar New Year?
edit:
I have JKBMS 2A active balancer, coupled with automated/manual Heltec 5A active balancer (depending on the deviation, mostly around 0.5A - 1A) and Neey 10A active balancer (darn it, this one is dead now). Can balance within 1 or 2 days easily.
Let me check my ancient screenshot :
Balancing in progress at 3.6V.........
Deviation was down to 0.077v from 0.128v at 3.6v balancing after 1 hour plus ?
It was balanced next day with deviation at 0.010v.....Unfortunately, I didn't take any screenshot after that.
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Robbert
Solar Enthusiast
It doesn't have to be much higher than 3.45. I charge to 55.8 (3.48) per cell. Absorbtion is 30 minutes and usually there is a deviation at the end of absorbtion, smaller than 5Mv.
I use B-Gade REPT cells and have approx 200 cycles.
timselectric
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You aren't balancing the cells as much at that voltage.
But if that's good enough for you, that's all that matters.
Were they new cells from a trusted source?My 16 cells 200Ah sinopoly are different,
All cells aged differently.
The worst cell only has 115Ah.
Removing it from the pack and stick with 15 remaining cells......
Until I noticed the second worst cell only has 140Ah while the rest have 160-165Ah......out of the 200Ah specification....so, there is that....
Cells were installed back in year 2019 with SPF5000ES (replaced with SPF6000ES now), when installed at the time, those cells had 185-190Ah......
Plenty of Sinopoly used cells were sold through cell brokers as new.
Nope, I have 20 Sinopoly (200ah) cells bought from questionable China online store (which opens a Shopee store) going through a freight forwarder before it reaches my address.
4 cells had around 110-120 Ah = disaster. But still useful to power my house 12 LED lights in Sarawak and in usage now. Using this programable solar charge controller, https://www.chinasuoer.com/mppt-solar-controller/252.html in conjunction with cheap Daly 4S BMS and Daly 1A active balancer. Just bought JKBMS 8S 2A BMS, no time going back home for installation yet.
16 cells seems to be functioning well around 185-190ah initially. Never expect such drastic capacity drop in just few years.
That was my biggest mistake in trusting the seller.
I can only hope the current seller SEPLOS will not bring such misfortune upon me......I had 18 EVE LF280K V3 order in place.......
Daddy Tanuki
Solar Wizard
plenty of CALB's as well.
Daddy Tanuki
Solar Wizard
and now I am hoping the Winston's I bought are actually from the factory. this seems to be the end result for all of us. buying cells from china and hoping for a miracle. This is my last chance 12K USD from Winston. we shall see. mind you the CALB's bought are obviously used... but they barely make things work, 2 or 3 days at best hoping to get 5 days, no solar out of them (Winston's) .. we shall see.
Brucey
Solar Wizard
You bought the calbs knowing they were used? Or they claimed new and shipped used?
Daddy Tanuki
Solar Wizard
claimed new shipped used or warehouse queens. I knew this going in. cheaper source for learning or testing.
Daddy Tanuki
Solar Wizard
anything at that price point was guaranteed to be used or a t best warehouse rejects. seller claims be damned. they are about sale, we are about final result.
Great, is that from personal experience , can you elaborate?
3800 days is over 10 years, which cells do you have? Im very interested in your longevity experience.Cycle counts for partial daily draws? I have serious doubts about accurate counting via any method.
Our battery is now approaching 3800 days of supplying somewhere in the region of 115Ah or 1.5 KWh overnight while the sun does not shine.
Someone else is welcome to perform any cycle maths.
Our 4 cell 300Ah Sinopoly LiFePO4 battery pack has now survived 10 years of full time travel both powering the motorhome and starting the 3.9l turbo diesel engine often multiple times a day.
I perform an annual C/10 capacity test each November. Converted to Ah the capacity has reduced from the original 315 to just 299. I expect a few more years of usable life.
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