Battery SOC minimum %

AchmatK said:
I always knew that I would want to add more batteries to the initial 3 I bought and pylontech was the only battery manufacturer at the time that specifically stated that their batteries could be mixed with different capacities so opted to go with pylontech.

Seems like only the US2000 batteries. View attachment 1872403View attachment 1872404
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Are we able to see cell voltages when absorbing?
 
AchmatK said:
Just checked how the batteries are being discharged and the BMS seems to manage discharge rates drawing more from the newest battery while the 3 from when it was new is being discharged at a lower rate.

Probably due to them having lost more capacity over the 5 years. View attachment 1872410
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I suspect that the BMS has no control over this behaviour. Its all down to internal resistance imho. BMS's are not this clever.
 
AchmatK said:
I'll check the cell voltage later this afternoon when it's at 100%.

This is what the UP5000 is reporting now. View attachment 1872435
Click to expand...
Please do. Thank You very much.

Do we know what balancer pylon has (active or passive? how many amps and when does the balancer start and does it continue when not in "charging" state?) and when and where they balance?

Experiment? Pylon is 15s. 3.65V x 15 = 54.75V.

Show me cell voltages at 54.75V?
 
wingnut771 said:
Please do. Thank You very much.

Do we know what balancer pylon has (active or passive? how many amps and when does the balancer start and does it continue when not in "charging" state?) and when and where they balance?

Experiment? Pylon is 15s. 3.65V x 15 = 54.75V.

Show me cell voltages at 54.75V?
Click to expand...
1766208774129.png

They might tell you overcharged them at 3.65
 
wingnut771 said:
Thanks for correcting me and showing pylon are a bunch of pussies where they only take their cell voltages to: 3.56V.

Correction: please show cell voltages at 53.5V?
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From powerforum a email to pylontech

We recommend that you use an inverter that can establish communication with the battery.




This inverter can work with our battery without communication, but you need to set the parameters manually.


The maximum charging voltage of the battery should be set to 53.2V, otherwise, the battery will be overcharged and damaged.




For US3000C, the cut-off voltage should be 47V and the max charge/discharge current should be 37A.
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I just don't like it that the BMS can stop cells from overcharging.

Seems like they are stuck in the past.

Also not that they are cheap by any means
 
DTBA said:
From powerforum a email to pylontech


I just don't like it that the BMS can stop cells from overcharging.

Seems like they are stuck in the past.

Also not that they are cheap by any means
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The above comments are like listening to a disgrunteled movie critic where they give a score of 3 while at the end of the day the public scores it a solid 8.8.
 
ghaye said:
My battery turned 5 years old at the beginning of October. I'm happy with the 100% state of health (obviously).

View attachment 1872128
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Have you ever runnit down to 0%

Soh is a capacity % so thisnknky gets updated when the battery actually does a full cycle ie it resets the counter to zero if the battery hits 2.5v or whatever the manufacturer set as 0%

And then counts the kwh charges until it hits 100% soc

And then divides this capacity by the pack capacity this % is then SOH

So if a battery never hits 0%
Then the SOH is a meaningless metric
 
leon.davibe said:
Have you ever runnit down to 0%

Soh is a capacity % so thisnknky gets updated when the battery actually does a full cycle ie it resets the counter to zero if the battery hits 2.5v or whatever the manufacturer set as 0%

And then counts the kwh charges until it hits 100% soc

And then divides this capacity by the pack capacity this % is then SOH

So if a battery never hits 0%
Then the SOH is a meaningless metric
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No offence but no one has a clue most of the time what youre trying to say.

To ease the mind, here is something to drift away:
 
wingnut771 said:
A cycle test for a 3.2V 100Ah LiFePO4 cell evaluates its longevity and capacity retention over hundreds or thousands of charge-discharge repetitions. The test typically follows industry standards (e.g., IEC 62619 or UN38.3) to determine when a battery reaches its "End of Life," usually defined as the point where capacity drops to 80% of its original rating.
1. Standard Cycle Procedure
A single cycle in a laboratory test generally consists of four sequential phases:
  • Constant Current (CC) Charge: The cell is charged at a standard rate, typically 0.5C (50A), until it reaches the upper cut-off voltage of 3.65V.
  • Constant Voltage (CV) Charge: The voltage is held at 3.65V while the current gradually tapers down. Charging stops once the current falls to a minimum threshold (e.g., 0.02C or 2A).
  • Rest Period: The cell sits idle for 10 to 60 minutes to allow chemical and thermal stabilization before discharging.
  • Discharge: The cell is discharged at a constant rate (e.g., 0.5C or 1C) until it reaches the lower cut-off voltage, typically 2.5V for a full 100% Depth of Discharge (DoD) test.
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Another interesting fact that i am sure many chose to miss

Eve says to stop usingbthe cells if it drops to 70% capacity

I suppose dendrites can eventually cause a short and at some point it should be regarded as useless

My bad cell is at 45% capacity and still works hasn't done anything

Have repaired (bms replacement) 2 other batteries
Will try and connect them today and get the bad one out so i can do the cell swop
 
leon.davibe said:
Another interesting fact that i am sure many chose to miss

Eve says to stop usingbthe cells if it drops to 70% capacity

I suppose dendrites can eventually cause a short and at some point it should be regarded as useless

My bad cell is at 45% capacity and still works hasn't done anything

Have repaired (bms replacement) 2 other batteries
Will try and connect them today and get the bad one out so i can do the cell swop
Click to expand...
Let me understand this properly, are you complaining about 10 000 cycles is not enough to get to 70% SOH?
 
B-1 said:
People who try and keep their lipo,life batteries full to increase their life do far more damage than they think they do.
If you want to decrease degradation keep them between 30 and 80% for the majority of the time.
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Yea but his is almost impossible
And then you ust cause damage at the bottom again

Lots of bms 's syol counting current under a certajn amount

On my bms's this is under 1A

1A is 1$ so if your battery spends a lotnof time at slow charge

Which a lot try and do to get 100% out of their solar

Then you see drift so this drift will mean you are spending time in 0-20 while you think you are in 20-40

Now yes system size dependant

Imo hitting 0% is way worse for a pack as rgat causes cells to drift way more

Passive bms incapable to sort out this imballance

Have a pack pack hat was saved (abused) with 20-80

6 months of trying whatever i can to get the bms to get this balancing sorted failed

Eventually i just manually balanced the cells

Now 14 of the 15 cells stay in balance

So yea i think 20-80 breaks more batteries than it saves
 
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