JK 4s BMS - Issues Resolved Yet?

I saw a number of posts about failed JK BMSs over the last year. Most of the problems seemed to be for units that were designed for 4S. The 8S-16S units seemed to be more reliable.

Anyone know if JK has solved their reliability issues for the 4S units? Or is the recommendation still the JBD for 4S builds ( despite the JBD's low passive balancing)?

MP

Marinepower said:

Anyone know if JK has solved their reliability issues for the 4S units? Or is the recommendation still the JBD for 4S builds ( despite the JBD's low passive balancing)?

MP

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Between November 2022 and now I have used a total number of 32 units Type JK B2A8S20P without any problems. One of the units did not accept its password. With the help of Jikong this problem was resolved. 16 units are operating in the 4S configuration, the other 16 units operate in an 8S configuration.
Recently I ordered 3 units Type JK B2A8S30P (300 A). All 3 units have the same problem: when recovering from an UVP event, the discharge MOSFET remains OFF and an error message says: Discharge On Failed. You need to enter the password in order to turn the Discharge MOSFET On manually. In case the load is removed before the UVPR recovery takes place, there is no such failure mode. Also these units have a "parallel" connector and a "C-" terminal. I could not find out, what these are good for. The status page also shows a "Pre-Discharge" status. Again no idea what it means.
I ordered also 2 units JK B2A25SRP which use external relays (no MOSFETs) to disconnect the battery in a failure case. Besides the fact that there is no valid wiring diagram available, these units show several strange things. The SOC algorithm doesn't work and the remote control Display comes on unintentionally.....

I recently replaced an older SOK BMS (non-bluetooth) with a B2A8S20P from the Hankzor store bought in November 2023. It's hardware version V11.XW software version V11.288.

While it doesn't have much mileage on it because it's for my trailer that I don't drag around in the winter, I have noticed the following differences that people tend to complain about on this forum:

- Logging works. It's still 50 lines but new entries do replace old ones.
- SOC reset to 100% worked for me with my settings.
- No password issues. I've updated the app 3 times now on 3 different android phones using very different hardware/android versions. Did not cause any problems for me, however I also don't forget my password.
- Bluetooth seems quite strong, I can connect to the battery from a Pixel 8 with the battery downstairs and myself upstairs. BMS is also inside a metal SOK battery box. Not sure if they changed something or if it's more dependent on your phone.

Just my experience, hope that helps.

Ep1phany said:

I recently replaced an older SOK BMS (non-bluetooth) with a B2A8S20P from the Hankzor store bought in November 2023. It's hardware version V11.XW software version V11.288.

While it doesn't have much mileage on it because it's for my trailer that I don't drag around in the winter, I have noticed the following differences that people tend to complain about on this forum:

- Logging works. It's still 50 lines but new entries do replace old ones.
- SOC reset to 100% worked for me with my settings.
- No password issues. I've updated the app 3 times now on 3 different android phones using very different hardware/android versions. Did not cause any problems for me, however I also don't forget my password.
- Bluetooth seems quite strong, I can connect to the battery from a Pixel 8 with the battery downstairs and myself upstairs. BMS is also inside a metal SOK battery box. Not sure if they changed something or if it's more dependent on your phone.

Just my experience, hope that helps.

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I ordered a JK B2A8S20P yesterday from the Hankzor store. I let you know how it goes. Thanks for the tips and recommendations.

MP

Marinepower said:

I ordered a JK B2A8S20P yesterday from the Hankzor store. I let you know how it goes. Thanks for the tips and recommendations.

MP

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I just commissioned mine today, picked it up last fall for my 24v conversion.

I did have to enter in a password 1234 for bluetooth to sync to the iOS app which I thought was odd.

Also my DMM on diode test was able to turn the BMS on (a cheapish fluke), the power switch connector came busted, less than a second and the red led came to life with a beep or two.

I ordered my first JK 4s w/1A balancer for small 12v project to give lights and power for a chicken coop. Finally got it installed and running Friday. So far so good, no issues yet. No problem connecting or setting up. However YT videos are the only way to learn settings, installation etc that I am aware of..
I’m sure most of you that have/had JK BMS’s before know this. Amazing that it came with NO info at all. From everything I’ve seen on this site, JK’s are very good and reliable BMS options. I ordered it and received it, before I was aware that there had been a few issues with these BMS’s recently. Hopefully all is well now.
I’ll post any info or issues if they arise.

I have two B2A(4-8)S200 Initially they worked well and still do. Turned on in Sept.

In Dec updated the firmware while 1200 miles away from home base, where they were installed. After that have received the BT fail to connect error. I've gone through 4 attempts with a new password from JK/China, and that will only work for about 10 minutes before I am locked out.

In the mean time the BMS have done their job, but I can only make a change during those 10 minute openings with the special BT password. We are back home, and hope to get another BT password that will ALWAYS work, as it use to do. The BT password is different the settings password, which can be changed, once I'm back into the system. I'm wondering if being away from the 'location' where I installed the BMSs makes a difference. Will know tonight, hopefully, or the seller is going to replace these two BMSs.

My main concern is that any replacement of the same version bms will result in us being locked out again, if we update the app version.

SpankyOatmeal said:

I have two B2A(4-8)S200 Initially they worked well and still do. Turned on in Sept.

In Dec updated the firmware while 1200 miles away from home base, where they were installed. After that have received the BT fail to connect error. I've gone through 4 attempts with a new password from JK/China, and that will only work for about 10 minutes before I am locked out.

In the mean time the BMS have done their job, but I can only make a change during those 10 minute openings with the special BT password. We are back home, and hope to get another BT password that will ALWAYS work, as it use to do. The BT password is different the settings password, which can be changed, once I'm back into the system. I'm wondering if being away from the 'location' where I installed the BMSs makes a difference. Will know tonight, hopefully, or the seller is going to replace these two BMSs.

My main concern is that any replacement of the same version bms will result in us being locked out again, if we update the app version.

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I’ve read/heard other have issues after doing updates on JK BMS’s but other devices, inverters as well.
I would assume you could skip doing any updates at all to maybe avoid issues if all is well?

I’ve had issues with my main house inverters after doing updates. Once the issues were resolved, I no longer accepted updates and things worked well.

Shawn Hayes said:

I’ve read/heard other have issues after doing updates on JK BMS’s but other devices, inverters as well.
I would assume you could skip doing any updates at all to maybe avoid issues if all is well?

I’ve had issues with my main house inverters after doing updates. Once the issues were resolved, I no longer accepted updates and things worked well.

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Shaun, I got the info on the BT password solution here at the forum from Ep1phany, great what to do, solved that issue I had of several months. So far the BMS have been working well, and fortunately they were setup correctly before the BT password thing hit while on a two month road trip.

Mine arrived from the Hanzor store.

Installed and commissioned & so far no issues. But I have not had to enough time really tell yet re overall performance.

I believe these BMSs run internally on 24volts and there was an issues for a while (2022) with the built-in boost/buck converter for the 4s (12v) models.

Seems to have been resolved...

You running it at 4s?

740GLE said:

You running it at 4s?

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yes, see OP