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Sunsynk 8.8kw and JKBMS

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pedro54

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Joined
Jun 15, 2022
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28
Hi,
I’ve created a DIY battery with a JKBMS. When I try to connect to the SunSynk inverter it doesn’t communicate. The JKBMS has canbus built in.

Has anybody been able to connect the two? Advice would be great.

Rj45
gnd - 2
h - 4
l - 5

JKBMS
gnd - red wire
h - black
l - yellow

SunSynk
selected Can and protocol 0.

Thanks
 

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Hi Pedro.

Nice to see someone using the JK BMS - I had been considering the Seplos myself (which I think should natively speak to the SunSynk/Deye inverter from what I can tell) but that unit feels a bit limited to me at just 150mA passive balancing. The JK unit would certainly be of interest with it's active balance capability.

Unfortunately I don't (yet) have an answer to your question, I haven't really found much at all on the CANbus protocol used by the JK BMS. Theoeretically a CANbus gateway would be easily possible, but native support would be even better (like Seplos option). Do you have any info on the JK? So far I see the alixpress advert just states '⑤:CANBUS interface ( Needs customized)'.

Happy to help with CANbus gatewaying if it does come to that.

Any info you can share may help,
Thanks
Ian
 
Hi Ian,

Yes I have these two canbus protocol documents one from SunSynk one from JK. I can’t understand them ??
 

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pedro54 said:
Hi Ian,

Yes I have these two canbus protocol documents one from SunSynk one from JK. I can’t understand them ??
Click to expand...
Nice one, which exact BMS model did you go for? I'm pretty confused on the available options!

Where are you based?
 
Additionally, if possible, it may be worth asking both companies for a CANDBC file.
 
ircoopr said:
Nice, I'm in Leamington Spa, nice to meet someone based in the UK.

This looks like it may be worth a read: https://github.com/syssi/esphome-jk-bms/discussions/114

a CANDBC is a CAN database file, just makes things much easier in CANbus tools than having to make our own from those word documents!
Click to expand...
I have asked for the CANDBC file. See if they get back to me. I’ve sent a few emails to JkBms but have never had a reply ?
 
pedro54 said:
Hi,
I’ve created a DIY battery with a JKBMS. When I try to connect to the SunSynk inverter it doesn’t communicate. The JKBMS has canbus built in.

Has anybody been able to connect the two? Advice would be great.

Rj45
gnd - 2
h - 4
l - 5

JKBMS
gnd - red wire
h - black
l - yellow

SunSynk
selected Can and protocol 0.

Thanks
Click to expand...
many people are doing the same mistake. CANBUS is a interface, not a protocol. jkmbs has a specific CAN protocol not supported by sunsynk. So basically they won't communicate.

You will need to design a JKBMS-CAN to PYLON-CAN protocol translator, or a JKBMS-RS485 to PYLON-CAN

All JKBMS has an RS485 interface also.

Some people are working on a pylontech emulation for jkbms (the rs485 version).
here a project that may help you if your BMS has rs485 interface too. https://github.com/maxx-ukoo/jk-bms2pylontech


Or you can build one with an esp32 based board.
 
Last edited:
sergea said:
many people are doing the same mistake. CANBUS is a interface, not a protocol. jkmbs has a specific CAN protocol not supported by sunsynk. So basically they won't communicate.

You will need to design a JKBMS-CAN to PYLON-CAN protocol translator, or a JKBMS-RS485 to PYLON-CAN

All JKBMS has an RS485 interface also.

Some people are working on a pylontech emulation for jkbms (the rs485 version).
here a project that may help you if your BMS has rs485 interface too. https://github.com/maxx-ukoo/jk-bms2pylontech


Or you can build one with an esp32 based board.
Click to expand...
Hi,
Thanks, that looks neat. It doesn't really say in the README how to use? Anybody used this? Any help would be appreciated.
 
you may need to contact the author if you are not familiar with building and flashing on STM32 platform.
 

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Jikong ought to develop this themselves.
It is one of the most popular BMS, but suck it could not communicate with inverters.
They even discourage users from paralleling JKs! sheez!
 
i want to share something with you guy, maybe you can help me ?
i bought 2 JK-BMS (B2A8S20P)
at first both worked perfectly, and with no reason one stop working ! :(
here 2 videos, one with the BMS ok and the other one with the bad BMS

JK-BMS - Google Drive

drive.google.com drive.google.com
 
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