JKBMS settings

Modifications
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46

You do have Charging Float Mode enabled on the Control tab of the JK-BMS app?

47

I will provide in some days, as the battery is at the customers house.
@dick yes, it is enabled for sure

48

Ok, checked yesterday the settings with the owner, sorry, forgot to make scrrenshots. :see_no_evil_monkey:
But, following for sure: RCV was 3.60V, RFV was 3.50V and 100% Voltage was 3.59V (total 57.44V).
Ok, sure, cant work, as the max. Cell Voltage is all the time ~3.56V (total ~56,96V).
So we changed the 100% Voltage to 3.55V, which is 56,8V total.

I told the cerbo to load the battery to 100% and looked if that fixes the 100% problem, it does not:

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The Battery was over 4h (RCV Time is 1h) over the desired 3.55V and it still does not change to 100%. Any Ideas what I can do?

49

Hi,
After 1h (RCV time), the battary voltage should be more than SOC-100% Voltage (3.59*16=57.44V).
Algorithm for JK BMS v15.35+

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50

Yes, that is exactly that what Andy said and how it should work, but it does not.
RCV-Timer is set to 1h and RFV-Timer is set to 8h.

We changed the 100%-Voltage to 3.55V yesterday at 20h PM, I set the minimal SOC to 100% and let it charge until today morning 7:30. So around 11.5 hours. but it stll at ~77% SOC:

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Or do we need an new cycle? :thinking:

Edit: I saw now, we have an new cycle, since 12:57, so more then 1h, but still at 78% although the voltage was always >=3.56V per cell:

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I dont understand this… :expressionless_face:

51

Your cells don’t get RCV (3.60), it’s always less :thinking:
Have you tried to calibrate the BMS voltage?

52

Not yet, maybe need to to do it, what voltage should I take, from multimeter on terminals of battery, from victron terminals or the voltage measured by victron itself?

Edit Victron itself is measuring something else:

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Should I calibrate it to that Voltage?

53

I did it on the battery terminals.
Maybe it’s better to check the voltage on the cells before the JK BMS.
My diff:

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54

It will be the voltage of the JKBMS as that is the device who sets your SOC level back to 100%.

I can confirm this is working on my side. But I’m using a 1h RCV-Timer value! And my cells are loaded to 3,45V (55.2V total).

55
  1. Always top balance your cells on a DIY battery pack
  2. Calibrate the Voltage with a 2-digit multimeter.
  3. For amp calibration, you need a constant source, but fw 19.10 also has 0 Ams calibration.
  4. For Victron, disable float on JK
  5. Use the settings from this spreadsheet (Specifically, column D, as provided by Andy) as a starting point.
  6. Ignore the SoC from JK; it’s rubbish
  7. Use the Victron Shunt, forget about JK

I prefer aggressive settings, and the batteries should last 10 years. I hope to live another 10 years and upgrade the packs.

56

@Courage2000 Some points are true, others I can’t agree

  1. For sure :+1:

  2. That I did now on Friday, from 59.94V to measured 57.89, since then it works fine! After 1h the SOC changes to 100%
    Surprisingly it also rise up the Cell Voltage, didn’t expect that, but yeah, makes sense:

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  3. Amp calibration was fine for me.

  4. Why? As You see, after 1h RCV, it went down to 56V RFV, which last for 8h, then back to RCV.

  5. I did, directly after the V-Calibration, my Settings looks like that:

    Screenshot_2025-08-08-19-37-47-968_com.jktech.bms
    Screenshot_2025-08-08-19-37-47-968_com.jktech.bms588×1306 105 KB

    Screenshot_2025-08-08-19-37-56-052_com.jktech.bms
    Screenshot_2025-08-08-19-37-56-052_com.jktech.bms588×1306 110 KB

    Screenshot_2025-08-08-19-38-05-667_com.jktech.bms
    Screenshot_2025-08-08-19-38-05-667_com.jktech.bms588×1306 101 KB

    Screenshot_2025-08-08-19-37-30-340_com.jktech.bms
    Screenshot_2025-08-08-19-37-30-340_com.jktech.bms588×1306 149 KB

  6. I wouldn’t say that, I have that BMS in over 25 Installations and it is counting very well the SoC and is the best BMS I saw until now. Its also the only SoC I would rely on, because its the only one which sees every cell. :+1:

  7. For Capacity, sure, for SoC, no. See 6.

Thanks a lot for help!

57

Use someone here the jk v19 bms? It’s a pain in the…. No idea what should I do with charging and discharging on absorption.

58

An updated question.

Now that v19 of JK BMS is being sold, does anyone have a recommended advance settings list for 10%-90% utilization of LiFePo4 MB31 cells?

59

For people searching why CCL goes to zero and how to overcome this when all other things of your setup have been verified and ok.

Need help with JK BMS and Deye inverter. | DIY Solar Power Forum is an article which has a post about “disable PCL module” on, PCL module is the buck inverter inside the V19 (and other JK BMSes) which, when an over charge current situation has been measured, swithces on the buck inverter with a limitation of 10A. Only way the BMS switches this off is if it measures 5A charge current or less.

When your setup should not switch off the charge current you could opt to disable the PCL module, in that case when a charge overload happens, the BMS will switch charging off, then after 60 seconds it will try to charge.

Suffice to say, your setup must be ok otherwise you’ll break things.

When you are doing maintenance on your packs, make sure disable PCL module is off, otherwise the inrush current might kill your system.

Hope this helps someone as I looked for this solution for a month and couldn’t figure out why my v19 BMS was behaving this way.

60

This is a classical hymera…