Hallo i keep wondering why my Pylontech keeps losing amperage, i have about 271 cycles on a us2000 plus it started losing amperage now i am at 48,6.

can somebody explain this phemonen, i taught we are supposed to have minimum of 6000 cycles with a brick if this continues i might loose the brick in 2years thanks

I checked my own graphs and found that my stack is losing about 1% capacity every 3 months.  That's 4% per year, so 80% capacity should come up after 5 years.  I have no idea whether the degradation is linear, though...

Oh, and congratulations on getting your dashboard built 😎

39 minutes ago, ChristoSnake said:

Oh, and congratulations on getting your dashboard built 😎

All thanks to you Christosnake you are the best, you PDF made it possible

11 hours ago, ChristoSnake said:

I have no idea whether the degradation is linear, though...

Degradation is usually highest at the start, then becomes somewhat linear after the first year or two.

@desiji, @ChristoSnake What is your daily DOD?

I'm trying to keep mine above 40% daily in the hopes that this massively extends the cycle life of the batteries.

I am wondering how the temperature is influencing the available capacity, see yours is running at 36°C

21 hours ago, desiji said:

i have about 271 cycles on a us2000 plus it started losing amperage now i am at 48,6.

does anybody know how the Pylontech battery BMS actually determines the capacity? I have my doubts if this figure is very accurate. 

46 minutes ago, Fuenkli said:

does anybody know how the Pylontech battery BMS actually determines the capacity? I have my doubts if this figure is very accurate. 

I don't see why it cannot be accurate - since it is an integrated BMS/battery.

Usually you will have a model of the battery - say that you know when it is new, from full to say 3V/cell is 30% DoD (values are for illustration only.), then you can directly measure capacity every time you go past 3V. There should be a couple of such calibrated points - the most accurate of which would be 100% DoD. You also know the cycle efficiency, so you can do the same while charging.

Your model should also then adjust the table as the capacity changes - at new 30% might be 3V/cell, by the time it reaches 40Ah, it might be 2.8V/cell and so on.

Of course, if you buy a battery from one supplier, and a BMS from another, everything gets a lot more fuzzy, but with a big supplier like pylontech it is possible to get very accurate.

 

(And I am only speculating, I do not know how they actually calculate it.)

13 minutes ago, P1000 said:

the most accurate of which would be 100% DoD

I agree. But this is never rally happening. That is why I am skeptical.

2 hours ago, PaBz0r said:

I am wondering how the temperature is influencing the available capacity, see yours is running at 36°C

Would also like to know that . Although keeping the battery room at 25 to 27 C ,  ICC temperature is 30 to 32 C .

10 hours ago, viceroy said:

@desiji, @ChristoSnake What is your daily DOD?

I'm trying to keep mine above 40% daily in the hopes that this massively extends the cycle life of the batteries.

Mine discharges down to 30-40% nightly for about 275 cycles per year.  Winter day/night temps are 20-25 deg C and in summer 30-35 deg C.  Charge current for the four of them is limited to 75 A, or less than 20 A each (way below the suggested charge current per brick).  Charge & float voltages both set to 52.5 V.

My goal is to massively saving on electricity consumption, rather than massively extending battery life 🤣

Watched this video last night pertaining to how long lithium batteries last, and some tips to extend that life.

I have also seen a drop is AMPS, I think this is normal. One must be worried when it drops by 20 to 50 percent.

A few here and there is because of the climate I think.

 

Running 4 US 3000B and they don't shiver and shake, standing strong.