JK 4S 200A BMS Electrical Noise

[Bari Rosch]

There is a statement on the forum @Nami that there were about 20 units initially JKBMS 4s-8s that had a DC DC converter ( because the basic circuitry of the JKBMS needs >25V) that consumed current and become hot and unstable. This DC DC converter chip has been replaced to a more efficient one. I am not sure if this relates to the noise problem. Apparently the faulty JKBMS 4s-8s units drew 1600mW. The newer fixed ones draw 800mW and the JK BMS7s-20s draw 560mW. For those that may still have these faulty ones in use, would be keen to know what the resting current draw is.
see https://diysolarforum.com/posts/610374/

Oke, hopefully my unit was one of those 20. I did not check the current draw before I returned it, as this was still unknown at that time. My electrical knowledge is not sufficient to be able to judge whether these specific chips (with resulting higher current draw) cause the issues experienced (interference with BMV and Multiplus).

I finally added a video with the sound recordings of the Multiplus: https://diysolarforum.com/threads/jk-bms-4s-combined-with-victron-bmv-712.46612/post-619819. It does not sound healthy, not sure what it is, but does/can it damage the Multiplus?

I did not see a response from Nami, so curious where you got this number (20x)/info from. I returned/shipped my unit to china around 2 weeks ago, might take a few more days/weeks before they receive it and hopefully they ship me a new one.

 

[ocular]

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I did not see a response from Nami, so curious where you got this number (20x)/info from. I returned/shipped my unit to china around 2 weeks ago, might take a few more days/weeks before they receive it and hopefully they ship me a new one.

This the post:

 

[ocular]

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I did not see a response from Nami, so curious where you got this number (20x)/info from. I returned/shipped my unit to china around 2 weeks ago, might take a few more days/weeks before they receive it and hopefully they ship me a new one.

Post in thread 'JK BMS Current Consumption (JK-B2A8S20P-H)' https://diysolarforum.com/threads/jk-bms-current-consumption-jk-b2a8s20p-h.41203/post-545389

 

[Bari Rosch]

Hey all, after some time I received a new BMS. I had some time today to install the new BMS and test it. Unfortunately I'm running into the same issues as before. Wrong reading on BMV-712 and arcing sound. Im really wondering if im doing something wrong and/or how this issue can be resolved. I made a video of the setup. Let me know what you guys think.

 

[Sky-HHI]

Does your jk bms have active balanceing ? Do you think it may be the bms trying to balance while charging. Could you turn the balance off during charging to see if there is a difference.

 

[Bari Rosch]

Does your jk bms have active balanceing ? Do you think it may be the bms trying to balance while charging. Could you turn the balance off during charging to see if there is a difference.

Hey, thanks for your reply. I tested this, by toggling on/off the balance/charge/discharge options, no effect. Also balancing is set to start only above 3.45V per cell and currently only seeing 3.30V, so not seeing any balancing activity.

 

[nvbt]

I have encoutered the same issue. Charging with simple CCCV charger gives arching noise. While connecting crocodiles it is even possible to see regular sparks between contacts and feel the noise by hand .
I have figured out that placing a finger over the first row of mosfets or pressing them can eliminate the noise completely. And sometimes there is no noise and charging is ok. I would imagine that this is related to some instability or parasitic feedback effect of mosfet driver circuitry. Or maybe a faulty mosfet somehow chort the gate to drain/source and driver is restarting.
The current passing through the BMS is essentially lower, in my case 50A during direct charge and about 20A through BMS. It meas it is like PWM modulation.