JK BMS: canbus AND/OR rs485

[solarrig]

Hello,

i'm looking for the answer and can't find it.


I've bought JK BMS and got confused, and nobody can answer me. When buying i have chosen CANBUS version, because in the manual i found this line:

"3.All models can support the following interfaces and functions:RS485 interface/CANbus interface/Heating interface,The price of each function is increased by 3.5USD on the basis of the above."

I understood that ALL BMS have RS485, but if i add extra 3,5USD, i will get RS485 + CANBUS. So i added extra 3,5USD.

But now i got confused, do i really have as well RS485?

So my question if i bought CANBUS, is it still possible to use RS485 if needed? Ir my BMS does not have RS485 anymore and ONLY have CANBUS?

Thank you.

 

[alferz]

First off all things JK BMS are rather mystifying due to multiple sellers and nascent documentation. The way I understood it, is that the JK BMS is manufactured to be capable of speaking any of those protocols, but it's activated in the firmware prior to shipping, only if you pay. It's kind of like a Tesla limited to a certain KWh output on its motors unless you pay $10k more. But this is only a theory. I asked the sellers on Aliexpress and no one seemed to have the same answer. If you need RS-485 I recommend paying for that option just to be sure. Even then you might need a special TTL -> RS-485 adapter (some sellers sell these and others dont, claiming the GPS port can speak RS-485 natively). To further add to the mystery, the JK BMS app has a "Port Switch" option which seems to let you select between CAN and RS-485. If you didnt pay for either of the protocol options, who knows?

For me, the 4-pin port labeled GPS seems to speak TTL just fine so I'm skipping CAN and RS-485 and just reading data using a USB-TTL adapter from Amazon. I ordered my B2A8S20P with the extra $5 RS-485 support via Heltec's store on Aliexpress. If you dont order with the support maybe TTL won't work? Only one way to find out.

 

[Cheap 4-life]

First off all things JK BMS are rather mystifying due to multiple sellers and nascent documentation. The way I understood it, is that the JK BMS is manufactured to be capable of speaking any of those protocols, but it's activated in the firmware prior to shipping, only if you pay. It's kind of like a Tesla limited to a certain KWh output on its motors unless you pay $10k more. But this is only a theory. I asked the sellers on Aliexpress and no one seemed to have the same answer. If you need RS-485 I recommend paying for that option just to be sure. Even then you might need a special TTL -> RS-485 adapter (some sellers sell these and others dont, claiming the GPS port can speak RS-485 natively). To further add to the mystery, the JK BMS app has a "Port Switch" option which seems to let you select between CAN and RS-485. If you didnt pay for either of the protocol options, who knows?

For me, the 4-pin port labeled GPS seems to speak TTL just fine so I'm skipping CAN and RS-485 and just reading data using a USB-TTL adapter from Amazon. I ordered my B2A8S20P with the extra $5 RS-485 support via Heltec's store on Aliexpress. If you dont order with the support maybe TTL won't work? Only one way to find out.

Does any of what u said allow me to see my batteries voltage on my iPad while sitting on my couch? Bluetooth doesn’t reach

 

[alferz]

Does any of what u said allow me to see my batteries voltage on my iPad while sitting on my couch? Bluetooth doesn’t reach

Yes, or half way around the world for that matter. But you have to work for it. JiKong not making it any easier for you. I view my battery status using a custom nodered dashboard i built as a single page web app from my ipad or phone. Some use grafana or other ways to display the data. But it’s definitely hands on coding type work. You could connect your ttl-usb adapter to a raspberry pi, then ssh to the pi to view the data via a quick python script. That is probably the simplest way unless you have a pc sitting right next to the bms.

 

[solarrig]

First off all things JK BMS are rather mystifying due to multiple sellers and nascent documentation. The way I understood it, is that the JK BMS is manufactured to be capable of speaking any of those protocols, but it's activated in the firmware prior to shipping, only if you pay. It's kind of like a Tesla limited to a certain KWh output on its motors unless you pay $10k more. But this is only a theory. I asked the sellers on Aliexpress and no one seemed to have the same answer. If you need RS-485 I recommend paying for that option just to be sure. Even then you might need a special TTL -> RS-485 adapter (some sellers sell these and others dont, claiming the GPS port can speak RS-485 natively). To further add to the mystery, the JK BMS app has a "Port Switch" option which seems to let you select between CAN and RS-485. If you didnt pay for either of the protocol options, who knows?

For me, the 4-pin port labeled GPS seems to speak TTL just fine so I'm skipping CAN and RS-485 and just reading data using a USB-TTL adapter from Amazon. I ordered my B2A8S20P with the extra $5 RS-485 support via Heltec's store on Aliexpress. If you dont order with the support maybe TTL won't work? Only one way to find out.

Thank you for your reply.
When i was buying it i understood that RS485 is by default build in and CANBUS cost additional few $. So i paid those few $ to have (what i understood) BOTH protocols. But now reading and seeing more i got doubt. Yes, i paid for CANBUS, so i have it. But do i still have RS485?. I have BMS already in my hands. And have no idea how to check it. If it's without RS485, then i will sell it as a new item (i did not connected it) and buy another, but this takes a lot of time. For me would be better if it's support RS485. But how do i check that. Today i've ordered JK RS485 adapter also RS485 to USB. But it will also take months to arrive, while BMS i would like to put in work (without connectivity) already today Not sure is it good that RS485 to USB or should i buy another more expensive. I need to connect it to Solar assistant.

 

[Aurgelme]

First off all things JK BMS are rather mystifying due to multiple sellers and nascent documentation. The way I understood it, is that the JK BMS is manufactured to be capable of speaking any of those protocols, but it's activated in the firmware prior to shipping, only if you pay. It's kind of like a Tesla limited to a certain KWh output on its motors unless you pay $10k more. But this is only a theory. I asked the sellers on Aliexpress and no one seemed to have the same answer. If you need RS-485 I recommend paying for that option just to be sure. Even then you might need a special TTL -> RS-485 adapter (some sellers sell these and others dont, claiming the GPS port can speak RS-485 natively). To further add to the mystery, the JK BMS app has a "Port Switch" option which seems to let you select between CAN and RS-485. If you didnt pay for either of the protocol options, who knows?

For me, the 4-pin port labeled GPS seems to speak TTL just fine so I'm skipping CAN and RS-485 and just reading data using a USB-TTL adapter from Amazon. I ordered my B2A8S20P with the extra $5 RS-485 support via Heltec's store on Aliexpress. If you dont order with the support maybe TTL won't work? Only one way to find out.

Can you verify if the bms output port (GPS) is 3.3V or 5 V TTL Levels ? I know the + pin is battery voltage so don't use it for isolated TTL to USB adapters without a voltage regulator

 

[Cheap 4-life]

Yes, or half way around the world for that matter. But you have to work for it. JiKong not making it any easier for you. I view my battery status using a custom nodered dashboard i built as a single page web app from my ipad or phone. Some use grafana or other ways to display the data. But it’s definitely hands on coding type work. You could connect your ttl-usb adapter to a raspberry pi, then ssh to the pi to view the data via a quick python script. That is probably the simplest way unless you have a pc sitting right next to the bms.

I guess I will have to do without because most of what you said sounds like Egyptian to me.. the bms should be able to hook right up to my router, wired or wirelessly.. then pull up a page on the net to view everything..

 

[alferz]

Can you verify if the bms output port (GPS) is 3.3V or 5 V TTL Levels ? I know the + pin is battery voltage so don't use it for isolated TTL to USB adapters without a voltage regulator

Mine is 3.3v on the rxout pin. Vout is full battery voltage so be careful with that one (i dont use it)

I guess I will have to do without because most of what you said sounds like Egyptian to me.. the bms should be able to hook right up to my router, wired or wirelessly.. then pull up a page on the net to view everything..

I think in a few years we will see BMS with native wifi and built in web status. The industry just isn’t quite there yet.

 

[alferz]

Here is how I connected mine. This is a Heltec branded version of the JK B2A8S20P. The top heatsink is screen printed a little differently but its otherwise identical to the JK. The 3rd port over when viewing from the bottom is a 4-pin, Micro JST 1.25mm port. Some of the JK versions have this port labeled RS-485/GPS. This port speaks TTL natively, so you can see the USB-TTL adapter I used (HiLetGo CP2102, $7 on Amazon). Ignore the wire colors I used in the picture since they are mismatched. You will need a 4-pin male micro JST 1.25mm pitch connector ideally with wires to connect to your USB-TTL adapter (got mine on eBay for $7). The pinout for the 4-pin connector is like this:

     <--------TOP OF BMS ---------->    
<TEMP port>    <3-pin port>    < o o o o >
                                 | | | |
                                /  | | \--- GND
                vout (28v!)----/   | |         
                                  /   \---  TXD (3.3v)
                     RXD (3.3v)--/

Once connected, you can use a simple python script like this one to read the BMS and verify communication is working.

 

[solarrig]

Here is how I connected mine. This is a Heltec branded version of the JK B2A8S20P. The top heatsink is screen printed a little differently but its otherwise identical to the JK. The 3rd port over when viewing from the bottom is a 4-pin, Micro JST 1.25mm port. Some of the JK versions have this port labeled RS-485/GPS. This port speaks TTL natively, so you can see the USB-TTL adapter I used (HiLetGo CP2102, $7 on Amazon). Ignore the wire colors I used in the picture since they are mismatched. You will need a 4-pin male micro JST 1.25mm pitch connector ideally with wires to connect to your USB-TTL adapter (got mine on eBay for $7). The pinout for the 4-pin connector is like this:

     <--------TOP OF BMS ---------->   
<TEMP port>    <3-pin port>    < o o o o >
                                 | | | |
                                /  | | \--- GND
                vout (28v!)----/   | |        
                                  /   \---  TXD (3.3v)
                     RXD (3.3v)--/

Once connected, you can use a simple python script like this one to read the BMS and verify communication is working.

Great. Thank you. Will try it

 

[vbaskoff]

Great. Thank you. Will try it

Hi,
Have you finally sorted this out? I have just ordered JK-B2A8S20P-H-C (with heater and can), and now trying to confirm if RS485 and CAN are supported simultaneously or not.

 

[solarrig]

Hi,
Have you finally sorted this out? I have just ordered JK-B2A8S20P-H-C (with heater and can), and now trying to confirm if RS485 and CAN are supported simultaneously or not.

I solve this problem. They call have this CAN/RS port. That port are preprogrammed from factory. You only can have one of them.
BUT.... there is GPS port and it ALWAYS in RS mode (except you have to buy adapter ±10USD). So so you can order CAN version, but also have RS

 

[solarrig]

https://www.aliexpress.com/item/1005005949340270.html?spm=a2g0o.productlist.main.5.66df0zU10zU1lT&algo_pvid=851cc4e6-d55b-42e8-b472-c9ac6d1cb14d&algo_exp_id=851cc4e6-d55b-42e8-b472-c9ac6d1cb14d-2&pdp_npi=4%40dis%21EUR%218.85%216.28%21%21%219.17%21%21%402101e9ec16970632473097865e2502%2112000034985426784%21sea%21LT%21921508398%21&curPageLogUid=CeO5Jt8VoqEI

But please note that different models needs different adapters.

 

[vbaskoff]

Thank you for reply! I have already ordered this adapter, so now I need get RS485 to USB to check GPS port operation.
HANKZOR also included new paper manual with JK-B2A8S20P-H-C, it is +/- clearly states that CAN/RS485 and GPS/RS485 ports are physically separate. So there is two variations (CAN and GPS/RS485) or (RS485 and GPS/RS485)

 

[Nobodybusiness]

Hello,

i'm looking for the answer and can't find it.


I've bought JK BMS and got confused, and nobody can answer me. When buying i have chosen CANBUS version, because in the manual i found this line:

"3.All models can support the following interfaces and functions:RS485 interface/CANbus interface/Heating interface,The price of each function is increased by 3.5USD on the basis of the above."

I understood that ALL BMS have RS485, but if i add extra 3,5USD, i will get RS485 + CANBUS. So i added extra 3,5USD.

But now i got confused, do i really have as well RS485?

So my question if i bought CANBUS, is it still possible to use RS485 if needed? Ir my BMS does not have RS485 anymore and ONLY have CANBUS?

Thank you.

Only thing I can tell you is that in the new one I just bought it is selectable in the app.

Does it use the same port for 485/Can?
I would imagine so since it’s selectable but I don’t know for sure.

 

[solarrig]

so what's the problem? Chooose what you need, and go for it!

 

[Nobodybusiness]

so what's the problem? Chooose what you need, and go for it!

I was trying to answer your question.

I don’t use either protocol so it’s absolutely no use to me whatsoever.

 

[LouFromDetroit]

I had a bit of a struggle with getting the RS 485 to work and I beleive the seller sent me the wrong adapter. Kind of related to the topic so I hope this can help someone. I have 2 working BMS with the my Raspberry running VENUS OS and was adding a third here.

Here is a pic of the older working one I have with another battery and BMS



Here is the translated text of the picture above using google lens - note the low voltage model




and finally here is the one the seller sent me with the BMS - I will be asking for a replacement

 

[Welly]

I had a bit of a struggle with getting the RS 485 to work and I beleive the seller sent me the wrong adapter. Kind of related to the topic so I hope this can help someone. I have 2 working BMS with the my Raspberry running VENUS OS and was adding a third here.

Here is a pic of the older working one I have with another battery and BMS
View attachment 186358


Here is the translated text of the picture above using google lens - note the low voltage model


View attachment 186359

and finally here is the one the seller sent me with the BMS - I will be asking for a replacement

That's interesting Lou, I have an even later BD6A20S10P version, but with very different setting options, and it's not working currently in spite of trying pretty much everything. After reading your post, maybe I was sent the wrong dongle too... but, I've also tried a direct TTL output from the BMS through an RS232 USB adapter and that doesn't work either.

Not helping the problem is being unable to change the selection under "Select UART Protocol", which is currently set to "000 - 4G-GPS Remote Module Comm...". Talking with the factory, through the eBay supplier is proving very testing and so far they are ignoring my concerns relating to the UART options and the RS485 being grey'd out (along with everything else).

Previously in this thread it has been suggested that certain configurations are factory set... I believe the GPS setting is one of these, inwhich case they sent the wrong, non-standard BMS... but trying to get them to admit this is proving difficult.

 

[LouFromDetroit]

Just to update here - I did get another "Low Voltage" adapter and my new 3rd BMS is working fine and communicating to my VENUS OS via USB The newer BMS sw screen does specifcally call out RS485 but the GPS port seems to work the same. So first they sent me the Hi Voltage model, then I got a bad Low voltage model, then my second low voltage model worked.