Connection over cable not possible JK BMS

AshleyL · 2024-07-14T17:43:03-0700

ScropusGobbleBottom said:
Yup, this is what happens to me with my 6000xp and is my biggest complaint... I didnt know what was causing that.

So far this happens with the JK inverter BMS and the victron shunt mod that converts it into a fake BMS

ScropusGobbleBottom said:
I have been periodically changing the battery amp hours in the jk bms every once and a while.
When you change that setting it results in a guess of SOC. If you do that when its charging and the soc drift is going to cut off soon, it will charge to the BMS cell cut off voltage. and default to 100%.

After this, change your requested charge voltage to less than the previous 100% setting and then it will never read 100%
It is fvcked....

The only solution is to reprogram the JKBMS firmware to report 99% SOC during RCV Time when 'Controlled Float Mode" is enabled and switch it to 100% when entering RFV Time. Easily done and can be fixed by JK.......but.........well you know....no luck so far.

Brucey · 2024-07-14T18:04:49-0700

AshleyL said:
Negative SOC drift and no time to balance cell.
The Voltronic inverter stopped charging the moment JK sent SOC 100% signal to the inverter.
SOC% 100 can be triggered by either inaccurate coulomb counting (it doesn't account for cell self-discharge rate either) and SOC100%-Volt setting in the JKBMS app.
Use the closed loop communication long enough or if you often use the battery down to 20 - 30% SOC, it can result in sudden LVD out of nowhere.

You have EG4? Now, try to check the app SOC % and compare with the individual cell voltage when the reported SOC% is close to 99 - 100% when using Pylontech protocol with JK Inverter BMS. You probably will notice none or only few of the cell actually hit 3.45V.

It can be fixed with firmware update, but highly unlikely....it is JK after all. This particular company only pays special attention to online influencers and not end users.

Ah, so because Andy doesn't have an eg4 or derivative JK just doesn't give a crap.

ScrotpusGobbleBottom · 2024-07-14T18:12:40-0700

AshleyL said:
The only solution is to reprogram the JKBMS firmware to report 99% SOC during RCV Time when 'Controlled Float Mode" is enabled and switch it to 100% when entering RFV Time. Easily done and can be fixed by JK.......but.........well you know....no luck so far.

But why did my moded Victron smart shunt as a BMS do the exact same thing at 100%?
The ONLY things shared between the 2 setups would be the EG4 6000xp and the Pylontec protocol .

AshleyL · 2024-07-14T18:28:54-0700

Brucey said:
Ah, so because Andy doesn't have an eg4 or derivative JK just doesn't give a crap.

Perhaps?

ScropusGobbleBottom said:
But why did my moded Victron smart shunt as a BMS do the exact same thing at 100%?
The ONLY things shared between the 2 setups would be the EG4 6000xp and the Pylontec protocol .

Sigh, the issue lies with the inverter itself too.

SMA Sunny Island and Victron inverters don't stop charging based on reported SOC%. For example, SMA inverter manual specifically mentions:

State of Charge – SOC: Sunny Island does not calculate the SOC of the battery system but relies on the SOC-Value
sent by the external BMS. This value should be accurately calculated by the external BMS as a lot of system functions
are triggered by the SOC-Value. For example the battery protection mode (see [1], [2]) is triggered by SOC or algorithm
for self consumption increase uses SOC value for the control purposes. Please note that charging of the battery will not
stop according to SOC value (for example at 100%). Only discharging of the battery is stopped by defined SOC-values.
It is expected that the battery provider detailed describes in his manual the definition of the SOC and the accuracy of the
value

Your modded shunt or JKBMS will have to work around the voltronic based inverter limitation.
Not to mention JKBMS coulomb counting is inaccurate and the way it triggers 100% is very problematic too.
EDIT: Technically, it would be fine if the SOC100%-Volt is not being trigged by only one cell, but rather all cell reaching the set voltage value, but then inaccurate coulomb counting gonna causes that SOC 100% as well, hence the proposed fix SOC 99% during RCV Time duration.

Both Voltronic OEM inverter and JK-BMS communication are mutually incompatible with each other. One will have to work around with another. In this case, both are not willing to compromise with each other.

ScrotpusGobbleBottom · 2024-07-14T18:34:17-0700

AshleyL said:
Sigh

Thanks for the details.

I original asked about the "big issue" thinking you might be talking about this

Connection over cable not possible JK BMS

AshleyL

Solar Enthusiast

Brucey

Solar Wizard

ScrotpusGobbleBottom

Corn Pop was a bad dude.

AshleyL

Solar Enthusiast

ScrotpusGobbleBottom

Corn Pop was a bad dude.

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