Brand new 280ah EVE cells shut off at 43% ah remaining, why?

[OffGridIdaho]

I will try to list the facts in order.

Observation number 1

When charging, my cell voltage climbs very very fast. Its as if Im charging a 100ah pack not a 280ah pack. If Im putting 30ah charge into SOC 20% of a 280ah pack it would take aprox 7 hours to charge yet it gets to shut off cell/pack voltage in 2.5hrs, which is not possible.

Observation number 2

Within seconds of charging the pack and termination at high cutoff the pack instantly loses 22% of its cell/pack voltage. It drops from pack V 27.5 to 26.5. I know it was fully charged as I saw the hockey stick climb of voltage right before it stopped charging. This is all 8 cells dropping from 27.6v to 26.5v at the same time.

Observation number 3.

This morning after using 191ah/43% SOC the pack shut off on low voltage while at rest and only a .5ah draw from sleeping inverter. I see a hockey stick down on graph from 25.5v to 23.3v.

Observation number 4

The pack voltage is always at least 20-25% lower in voltage then the SOC meter tells me its supposed to be. Example of last night. Meter said 43% and voltage said 19% with a .5a load. This is a 24v 280ah 3 week old eve pack that is kept warm in a house and never stressed. Normal running loads are 8ah. Max would be a toaster at 43ah for 3 mins. Charging takes place at 34ah.


Observation number 5

My JK b2a20s20p is always trying to keep cell 1 balanced. It spends 99% of its time on that cell. My delta at rest is .003. This morning when pack shut off that number 1 cell was 2.83v and the other 7 were 2.93v and delta was .078 at 0% soc.

Voltages were verified with expensive DMM after shutdown.

Currently I am charging the dead pack and have been charging for less then 2hrs at 34ah. My pack % meter on JK and victron show 30% soc and the cell/pack voltage shows (((26.8v/3.35v<<90% soc))) which is not possible with only a 68ah charge. Victron ah meter shows NEGATIVE -196ah remaining to charge. Which would sync up to the 68ah input over the last 2hrs. All cell voltages are very close to each other so its not one cell bring them all down. It seems like im running a 100ah pack instead of a 280ah pack.

Help, opinions, advise welcome!

 

[SeaGal]

Obvious but... I assume you have configured the BMS to know it is a 280Ah, rather than 100Ah battery?

 

[MisterSandals]

If Im putting 30ah charge into SOC 20%

How are you determining 20% SoC?
If its voltage based and there are a couple cells with very low voltage, those could climb quite a bit with minimal charge current (one of the problems with voltage based SoC determination, especially at the extremes).

instantly loses 22% of its cell/pack voltage. It drops from pack V 27.5 to 26.5. I know it was fully charged as I saw the hockey stick climb of voltage right before it stopped charging.

What charger are you using? Is there any absorption stage or does it simply terminate upon reaching some voltage?

This morning when pack shut off that number 1 cell was 2.83v and the other 7 were 2.93v and delta was .078 at 0% soc.

That's actually quite balanced for a battery that is 95% depleted.
(7 x 2.93V) + 2.83V = 23.34V
I'd be mighty happy with that!

and have been charging for less then 2hrs at 34ah. My pack % meter on JK and victron show 30% soc and the cell/pack voltage shows (((26.8v/3.35v<<90% soc)))

Are your voltage measurements taken while it is being charged or while the battery is disconnected and at rest?

 

[OffGridIdaho]

Obvious but... I assume you have configured the BMS to know it is a 280Ah, rather than 100Ah battery?

yes on both shunts victron, and jkbms.

 

[OffGridIdaho]

How are you determining 20% SoC?
If its voltage based and there are a couple cells with very low voltage, those could climb quite a bit with minimal charge current (one of the problems with voltage based SoC determination, especially at the extremes).

All cells have the same voltage as I stated in my observations. Yes by voltage at rest.

What charger are you using? Is there any absorption stage or does it simply terminate upon reaching some voltage?

That's actually quite balanced for a battery that is 95% depleted.
(7 x 2.93V) + 2.83V = 23.34V
I'd be mighty happy with that!


Are your voltage measurements taken while it is being charged or while the battery is disconnected and at rest?

Im using 2 chargers, 1 is a kid solar mppt and 2 is a EVO samlex inverter/charger. Both while charging at at rest. Currently the voltage shows 95% soc and pack meter(s) both show 42%. So its off by 50%. Ive lost half my pack ah,s

 

[OffGridIdaho]

Pack voltage shows soc at 95% and meter says 45% , it cannot be 95% as I havent charged enough ah into it to be there.
Pack ah meter says same as voltage when I can ONLY USE 191ah before packs shuts down. Missing almost half my pack.
Look at victron negative ah (-181) and yet voltage is at 95%.

 

[MisterSandals]

Currently the voltage shows 95% soc and pack meter(s) both show 42%. So its off by 50%.

That's unfortunate. I used to use a BMV but it drifted at different rates at different times. I ALWAYS checked the voltage against a SoC/voltage chart to verify the BMV.

After a while i stopped looking at the BMV and only looked at voltage. I can pretty much eyeball the voltage and know how my battery is doing:
13.0V = getting low
13.2V = where i have float set
13.3V = mostly full

I have an oversized battery so i do not need to know more than this.
The BMV has been gathering dust on the workbench for nearly 2 years...

 

[MisterSandals]

Look at victron negative ah (-181) and yet voltage is at 95%.

Can you post a shot of your Victron BMV settings?

 

[OffGridIdaho]

That's unfortunate. I used to use a BMV but it drifted at different rates at different times. I ALWAYS checked the voltage against a SoC/voltage chart to verify the BMV.

After a while i stopped looking at the BMV and only looked at voltage. I can pretty much eyeball the voltage and know how my battery is doing:
13.0V = getting low
13.2V = where i have float set
13.3V = mostly full

I have an oversized battery so i do not need to know more than this.
The BMV has been gathering dust on the workbench for nearly 2 years...

I dont think the meter is off I think the pack isnt holding the AH rating of 280ah. I think Im only getting around 190ah from the pack.
The victron shunt/meter is spot on. I rand a 20ah load for one hour and the meter dropped from -101ah to -121ah. the meter is correct, the battery storage capacity isnt.

I go by voltage as well.

Why would the pack voltage drop after charging by 1v (not .1v but a whole volt)

 

[OffGridIdaho]

Can you post a shot of your Victron BMV settings?

Its a victron smart shunt

 

[MisterSandals]

I reread from the top to see if i missed something. This caught my eye

It drops from pack V 27.5 to 26.5.

26.5V / 8 = 3.3125Vpc
27.5V / 8 = 3.4375Vpc

3.43Vpc is pretty low, especially without an absorb phase. Perhaps the cells are not getting charged fully. You are using pretty high amps too (40A charging!) so the voltage might rise with a surface charge without getting a good absorb.

I am a conservative charger and charge to 3.45Vpc at a slow rate (about 15A for a 412Ah 12V battery).

Maybe try raising the charge voltage a bit and lowering the amps significantly to see if they show better capacity.

Its a victron smart shunt

One thing i see is your charge voltage shows 28V (3.5Vpc) and you're only charging to 3.43Vpc.
Also, what is the "manually set Soc 49.7%"? Have you used that?

I'd update your shunt (BMV) "charge voltage" to where you are actually charging your battery. Personally, i consider my 100% Soc where my cells settle within an hour after a full charge (3.35Vpc for me).
I would try charging a little higher and a little slower. Let them settle for half an hour and consider that your full charge.

Hopefully this helps. I am believing you're not fully saturating your cells.

 

[OffGridIdaho]

I reread from the top to see if i missed something. This caught my eye

26.5V / 8 = 3.3125Vpc
27.5V / 8 = 3.4375Vpc

3.43Vpc is pretty low, especially without an absorb phase. Perhaps the cells are not getting charged fully. You are using pretty high amps too (40A charging!) so the voltage might rise with a surface charge without getting a good absorb.

I am a conservative charger and charge to 3.45Vpc at a slow rate (about 15A for a 412Ah 12V battery).

Maybe try raising the charge voltage a bit and lowering the amps significantly to see if they show better capacity.


One thing i see is your charge voltage shows 28V (3.5Vpc) and you're only charging to 3.43Vpc.
Also, what is the "manually set Soc 49.7%"? Have you used that?

I'd update your shunt (BMV) "charge voltage" to where you are actually charging your battery. Personally, i consider my 100% Soc where my cells settle within an hour after a full charge (3.35Vpc for me).
I would try charging a little higher and a little slower. Let them settle for half an hour and consider that your full charge.

Hopefully this helps. I am believing you're not fully saturating your cells.

OK , I will re-read that again. I will try anything at this point. I am very new to this and dont know my way around yet.
Can I get your settings and I will double them?
Charge voltage-bulk
Charge voltage-absorb
Charge voltage -float
Time absorb
End amps absorb
Charge amps per cell and what ah cells you have?

I have 8 280ah cell running in series at 24v. I was told you can charge them at 75ah safely. I usually run at 30 solar and 34ah generator. Are you saying that amps is too high for 8 280ah cells? Thats only 4.25a per cell for a gigantic 280ah cell.

 

[MisterSandals]

I was told you can charge them at 75ah safely.

Yes, agreed. But...
Your chargers are setup to charge to a voltage. You cells are getting to that voltage without completely charging the cells. An absorb phase (or slow charging) is necessary to completely saturate the cells (to full).

Getting your cells to a voltage, quickly, does not necessarily fill the cells.

Its kind of like when you fill your gas tank, it foams up to the top and cuts off the pump. To fill the tank you then need to pump slower to get it to the top (this is a cringeworthy explanation of absorb).

 

[bravo6]

OK , I will re-read that again. I will try anything at this point. I am very new to this and dont know my way around yet.
Can I get your settings and I will double them?
Charge voltage-bulk
Charge voltage-absorb
Charge voltage -float
Time absorb
End amps absorb
Charge amps per cell and what ah cells you have?

I have 8 280ah cell running in series at 24v. I was told you can charge them at 75ah safely. I usually run at 30 solar and 34ah generator. Are you saying that amps is too high for 8 280ah cells? Thats only 4.25a per cell for a gigantic 280ah cell.

The current does not reduce for series connected batteries. If you are charging 30 amps then all the cells are getting 30 amps.

 

[OffGridIdaho]

I reread from the top to see if i missed something. This caught my eye

26.5V / 8 = 3.3125Vpc
27.5V / 8 = 3.4375Vpc

3.43Vpc is pretty low, especially without an absorb phase. Perhaps the cells are not getting charged fully. You are using pretty high amps too (40A charging!) so the voltage might rise with a surface charge without getting a good absorb.

I am a conservative charger and charge to 3.45Vpc at a slow rate (about 15A for a 412Ah 12V battery).

Maybe try raising the charge voltage a bit and lowering the amps significantly to see if they show better capacity.


One thing i see is your charge voltage shows 28V (3.5Vpc) and you're only charging to 3.43Vpc.
Also, what is the "manually set Soc 49.7%"? Have you used that?

I'd update your shunt (BMV) "charge voltage" to where you are actually charging your battery. Personally, i consider my 100% Soc where my cells settle within an hour after a full charge (3.35Vpc for me).
I would try charging a little higher and a little slower. Let them settle for half an hour and consider that your full charge.

Hopefully this helps. I am believing you're not fully saturating your cells.

The "manually set soc" is just a way to calibrate it to what you have. If the pack shuts off on lvp you set it to 0 or shuts off high you set it to 100%.
Its just showing current reading at that second in time.

 

[timselectric]

I agree with you're not getting a full charge.

 

[OffGridIdaho]

Yes, agreed. But...
Your chargers are setup to charge to a voltage. You cells are getting to that voltage without completely charging the cells. An absorb phase (or slow charging) is necessary to completely saturate the cells (to full).

Getting your cells to a voltage, quickly, does not necessarily fill the cells.

Its kind of like when you fill your gas tank, it foams up to the top and cuts off the pump. To fill the tank you then need to pump slower to get it to the top (this is a cringeworthy explanation of absorb).

Or like filling a tap beer or tap soda. OK I get that.
Can you give me some settings as in above post to try?
Im currently at 59% soc and 26.93v
By my math and time-run/input amps Ive inputted around 150 amps +/- 10a
I need to charge another 125a +/- 10a

 

[MisterSandals]

Can I get your settings and I will double them?
Charge voltage-bulk
Charge voltage-absorb
Charge voltage -float
Time absorb
End amps absorb
Charge amps per cell and what ah cells you have?

I would set:
bulk: 13.8V x 2
absorb: 13.8V x 2
float (.02Vpc below where they settle within an hour after the above bulk and absorb charge... this prevents micro cycling).
absorb time to 20 minutes
End amps to 2A (mostly a wild guess)

This is a good start. You can always experiment slightly and see how it goes.
My battery is 8 206Ah cells arranged 2P4S (12.8V 412Ah).
Charge amps per cell is not quite the same with 2P4S since each "cell" is a pair that makes a 412Ah cell. I have 330W laying flat on the RV, have the max charging amps (set in Victron 100/30) set to 20A. I usually see 15A in the summer and I easily charge my batteries by noon (if i set max charging amps lower, i'd get a better and gentler charge... i will consider this next time out).

 

[MisterSandals]

Or like filling a tap beer

Of course! Now that i've done it so many times i never have to give it a thought...

 

[MisterSandals]

I agree with you're not getting a full charge.

Thanks. It took me a while to chew thru the red herrings to figure this out. Glad you agree.