Connection over cable not possible JK BMS

[AshleyL]

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

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]

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.

 

[ScrodusGargleRotten]

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]

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

Perhaps?

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.

 

[ScrodusGargleRotten]

Sigh

Thanks for the details.
I original asked about the "big issue" thinking you might be talking about this

 

[sarzyk]

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....

 

[sarzyk]

Try new firmware. Use UART1 position 14

 

[ScrodusGargleRotten]

Use UART1 position 14

Isnt that RS485 and not CAN?

 

[sarzyk]

It should be rs485. I can't try it because I'm on vacation.

 

[kommando]

From the changelog

V15.26 Upgrade logs
1. Fixed a Bug about DEYE inverter CAN communication protocol.
2. Fixed a Bug about Growatt inverter RS485 communication protocol.

@2024-06-20 by JKBMS


V15.26 Upgrade logs
1. Added support for the PYLON RS485 communication protocol.
2. Added support for the MEGAREVO CAN communication protocol.
3. Added product model JK-B2A24S30P.

 

[RCinFLA]

But in manual is Anern use one rs485.
Maybe the manual which I have is wrong too?View attachment 226825

The JK PB BMS comm interface board flips and rotates RS485 A & B connections between 1-2 and 7-8 on RJ45 connector. There are hard wire PCB runners on the JK PB interface PCB board connecting pins 1-8 and 2-7. This allows either end of the RJ45 cable to make proper connections.
JK PB BMS RJ45 also has pins 3 & 6 grounded to JK BMS ground and pins 4 & 5 open with no connections.

If the inverter CN2 RJ45 connector has pin 8 grounded then it will ground out the RS485 B signal line on the JK PB comm interface board.

You would need to make up a special RJ45 cable.

 

[Spok86]

Try new firmware. Use UART1 position 14

firmware 15.27 ??? the most recent i have find is the 15.24
where have you find this ? i go try

 

[AshleyL]

Try new firmware. Use UART1 position 14

Officially reporting after testing = no luck on the 100% SOC stop charging issue.

 

[Spok86]

for me always, no communication between inverter/bms. in pylontech low voltage rs485.
I mesured voltage between ground - a and between ground - b i have 2.4v BMS side and 1.2v Inverter side.
I want 100%SOC charging issue too ! :'(

 

[ScrodusGargleRotten]

So just to describe my problem because I think it may be the same for you all. I have a 6000xp with JK inverter BMS

Battery completes charge at noon. No float.
Loads exclusively powered by solar until load is greater than solar.
Load being greater than solar forces BYPASS to grid and uses NO battery.


This repeats for 5 minutes when a cloud passes over and loads draws more than the current PV input
It seems to me that it should use SOLAR and battery in this case....
Instead it turns into Solar/Grid battery-less mode For 5 minutes. It does not even try to use the battery after the battery hits full charge.

This is garbage.

Solar Assistant reports grid usage
Emporia Vue reports grid usage.

 

[EG4TechSolutionsTeam]

JK BMS is not officially supported by the 6000XP, which could be causing the issues you're experiencing. Additionally, while Solar Assistant is a great tool, we have observed that it can cause errors in data reporting to the server since it uses the same transmit and receive channels on the Wi-Fi dongle.

 

[JJJJ]

I am simply trying to connect the inverter to my computer. I tried the adapter and and cable style recommended by Andys Garage. Alas the computer cannot see the inverter

 

[kommando]

Not all adaptors are equal and depending on your Windows install not all rs485 chip drivers are equal.

In Device Manager check the Comm port, these are my settings that work, also on the JK PB BMS dip switch must be set to 1 to see settings, 0 for parallel.

Baud rate 115200
Data bits 8
Stop bits 1
Parity None
Flow control Half Duplex

 

[JJJJ]

If I am reading the documentation correctly for unit number one the switches would be on-off-off-off? Or am I backwards?

 

[kommando]

If I am reading the documentation correctly for unit number one the switches would be on-off-off-off? Or am I backwards?

No that sounds correct.

 

[JJJJ]

OK. So I could not get this unit to work, although it has worked for others:

https://www.amazon.com/dp/B081MB6PN2?psc=1&ref=ppx_yo2ov_dt_b_product_details

Just installed this and it is working very nicely:

https://www.amazon.com/dp/B07B416CPK?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

[RCinFLA]

All the USB to RS485 converters are two chips, one for USB to serial UART, followed by serial to RS485 driver chip. The RS485 chip requires enable control lines for switching twisted pair output wires between Rx data and Tx data.

Many cheap USB to RS485 data converters lacks a true control for Tx/Rx direction for the serial to RS485 chip. They just use Tx serial data fed into Tx/Rx direction pin. This means the RS485 jumps back to high-Z Rx mode during Tx '0' bits. That means the RS485 communications is relying on the twisted pair wire 120-ohm termination resistor to pull down Tx logic zero. Result is slow RS485 baud rate and data waveform distortion.

The best way to do it is for the RTS/CTS of the USB to RS232 converter output to provide the Tx/Rx RS485 direction control but this usually requires handshaking be turned on in the PC serial port driver. The FTDI USB to serial chip can create the Tx/Rx direction control for RS485 chip on its own.

Other thing you should look for is galvanic isolation of the USB to RS485 converter. These are a bit more expensive ($20) because they have their own isolated 5 vdc DC to DC converter and serial data isolation transfer chip to provide high voltage isolation for the RS485 communications wires. This protects the two interconnecting devices from ground voltage differences which is a very common issue for industrial applications.

 

[JJJJ]

Many cheap USB to RS485 data converters lacks a true control for Tx/Rx direction for the serial to RS485 chip.

This might explain why my first unit didn’t display Rx data and wouldn’t work

 

[Dmode]

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.

Officially reporting after testing = no luck on the 100% SOC stop charging issue.

Has anyone tried to communicate about this JK inverter BMS issue with the contacts listed on JK's website?

 

[kommando]

Has anyone tried to communicate about this JK inverter BMS issue with the contacts listed on JK's website?

Yes, the silence is deafening !!!!