JK BMS B2A8S20P (and family members)

[Pepijntje Madurodam]

The JK_BMS company : their hardware engineers are doing a great job. Their software engineers are too low level. JK top-management doesn't care ....
I'm checking the JK BMS protocols at the lowest possible level : with the logic analyzer. (((( no confidence in all those higher level hocus-pocus software stuff .... ))).
By now I have a large collection of examples about the JK BMS software "skills".

The popular B2A8S20P has a CAN port. On hardware version V11.XW , software version V11.287H : modify the device address (via the bluetooth app) will result in a modified CAN ID . Device address = 0 will yield ID 0x02F4 (or 0x04F4 or 0x05F5 for other parameter groups), device address = 1 will yield ID 0x2F5 , address = 2 will yield 0x2F6, etc. So far so good. The CAN protocol is the Standard Frame.
Another B2A8S20P : hardware version V11A, software version V11.54. One can change the device address (again via the bluetooth app), but the logic analyzer shows NO change in CAN ID !!!! Whatever device address selected, the analyzer always shows ID 0x2F4 (or 0x4F4 or 0x5F4). That's a major error. Forget to observe multiple JK BMS on a CAN bus.
On top of that, JK changed from Standard CAN protocol to Extended CAN protocol. Without any message to their customers.

Obviously JKBMS has communication problems with a lot of inverters.
JK is changing internals on the fly and when they improve one item at the same time they deteriorate another item.
Updating features is great, but you should inform the customers about it !
A JKBMS from last year is doing fine, so one order some more "identical" BMS. Forget it , they will have different behaviour.

The basic B2A8S20P (or family members) has a 4pin RS485 port. Forget it. It's a plain RS232 port, with the Vcc wire connected to the battery voltage (thus NOT to 3.3V or 5V).
(((that's why they sell the yo-do-not-need-it RS485 dongle to deal with this high power supply))). The optional CAN/HC version has an extra port with CAN functionality or RS485 functionality. The CAN story : see above. The RS485 story : that port is connected to the internal RS232 kernal, only the signal levels are RS485. No MODBUS, no whatsoever protocol. Again : pure RS232 "protocol" at RS485 voltage levels. And because of using the internal RS232 kernal, only one of the two "RS485" ports can be used at the same time.

A total mess. We (= the users) cannot have confidence anymore in JK BMS. Whoever : stop promoting JK BMS.

 

[Sleeper85]

Indeed this is not clear, I have the two models B2A8S20P V11.XW and V11A. Concerning communication with inverters I created YamBMS see the links in my signature.

That said, the JK remains my favorite BMS.

 

[Martygofast]

I have tried several RS485 adapters on the dongle for this BMS, but I cannot get it to show in JM-BMS-Monitor 2.7.
Version 11.54 is on the BMS and I am using the dongle te get from 4 pin to 3 and connecting the leads accordingly. When selecting the COM-port it will not show the data. What am I doing wrong?

 

[uksa007]

Obviously JKBMS has communication problems with a lot of inverters.

My iBMS boards solve this issue, and enable inverter comms with almost all inverters that support CAN.

 

[Sleeper85]

My iBMS boards solve this issue, and enable inverter comms with almost all inverters that support CAN.

Your iBMS costs an arm and a leg while YamBMS is open-source and can do the same thing for free.

 

[uksa007]

,Your iBMS costs an arm and a leg while YamBMS is open-source and can do the same thing for free.

Nothing in this world is free, you still need hardware, cables and power supplies and the time and skills to put it all together.

iBMS is an all in one plug and play solution, includes all the hardware, and power supply on one board.
Just plug it it and away you go, no building hardware and learning how solder and program, hacking modules together etc.
iBMS is fully supported and tested in 100's of installations.

 

[Koyaanisqatsi]

My biggest problem with what I am seeing with BMSes, whether built-in or bought separately, is that the companies are slapping "RS485" and other standard titles like that on some ports without actually implementing those standards on the port.

RS485, RS232 and TTL are all electrical/physical connection standards, not data/signal standards. Any data or protocol can be passed over any of them, and it's typically either MODBUS or basic serial data. For a company to label a port as RS485, and then run it at TTL, is an absolute error. TTL cannot be run over a RS485 connection any easier than you can run voice (an analog signal) over Ethernet (a digital connection).

CAN bus is a bit differnt in that it usually includes the pysical interface and the data protocol in "one" standard. But even that is not consistent across these devices.

 

[uksa007]

My biggest problem with what I am seeing with BMSes, whether built-in or bought separately, is that the companies are slapping "RS485" and other standard titles like that on some ports without actually implementing those standards on the port

Most are Chinese manufacturers, english/communication is not their strong suit and the message gets lost in translation.

JK-BMS generally label the TTL port as "GPS" as it was designed to be used with their GPS module, it can also be used with their RS485 adaptor if you need RS485.

 

[Sleeper85]

Nothing in this world is free, you still need hardware, cables and power supplies and the time and skills to put it all together.

iBMS is an all in one plug and play solution, includes all the hardware, and power supply on one board.
Just plug it it and away you go, no building hardware and learning how solder and program, hacking modules together etc.
iBMS is fully supported and tested in 100's of installations.

Of course the hardware is not free.

For a multi-BMS solution composed of 9x JK-B BMS

• with your iBMS board the cost is 9x $199 = $1791
• with YamBMS and M5stack hardware that fits together like LEGO without soldering the price is $75.5

As I said above, your solution costs an arm and a leg.

For a multi-BMS solution composed of 9x JK-PB my solution is even cheaper and only $24.95

The documentation I have produced allows most users to do it themselves.

 

[uksa007]

Of course the hardware is not free.

The cost is $149 for a Standalone CAN Bus Fully Isolated plug and play board, less if you are a Patreon member.
Most people one have one or two batteries, it's a small cost of the overall battery/system cost.

My system is modular and allows combining data from multiple vendors BMS and other CAN based batteries.
It is good people have options, not everyone wants an open source project, many are happy to pay for a plug and play, supported solution.

 

[Sleeper85]

The cost is $149 for a Standalone CAN Bus Fully Isolated plug and play board, less if you are a Patreon member.
Most people one have one or two batteries, it's a small cost of the overall battery/system cost.

My system is modular and allows combining data from multiple vendors BMS and other CAN based batteries.
It is good people have options, not everyone wants an open source project, many are happy to pay for a plug and play, supported solution.

$149 for a single BMS and $199 per BMS for a multi-BMS solution.

Most users have more than one battery.

About 50 users use YamBMS, some with a large number of BMS like 9.

Indeed it's not bad to have options so let's let users choose.