my JK BMS 4s Version runs fine for month but now it wont come up anymore. First i had a Error in the app that my Cell Count doesnt match (no cells visible) then after restart it comes with some beeps and then it makes a terrible noise over and over. In the Display i´ve seen Error Code 4 and now 7.
Following the general hype train about the JK BMS, I've jumped on board and got myself one as well.
I've recently started experiencing the same issue though, with my JK BMS B2A8S20P (no heating version) attached to my 12V, 4 cells, 280AH battery.
What I managed to understand until now is:
Issues started as soon as the winter came and temperatures started to drop down to or slightly below 0°C (32°F). All summer long there were no issues whatsoever.
First I noticed in VRM dashboard that the voltage suddenly dropped by around 0.6V (in just a few minutes) with no loads at the moment. I later found somewhere that this is normal in cold weather and that it's just something that BMSs do.
Then I tried connecting to the BMS with the app and it worked, but I had the same error that you mentioned, that no cells were detected and the beeping started.
No beeping at all before connecting with the app to the BMS.
Beeping never stops after that. It seems there are 2 repeating beep codes: fist I think 4 short beeps and a long beep at the end , and the second one maybe 9 short beeps and final long one and then it repeats.
Connecting with the app after the beeping starts, is impossible. The BMS is detected, but I can no longer connect to it.
The voltage at the battery terminals is zero after the beeping starts, so the battery becomes useless.
If I stop the BMS from the button (long press for around 10s) and restart it, the beeping just keeps on going as before, no matter how long it was stopped. I tried leaving it stopped over night and the next day when I started it, the beeps started immediately.
The only workaround for this annoying beeping issue that I found is to press the power button of the BMS for around 3 seconds. The beeping stops and everything comes back to normal, with normal voltage present at the battery terminals. No idea what this does since I couldn't find anything in the manual about it. After this, connecting with the app to the BMS is once again working, cells are detected and everything looks normal except in a few minutes the beeping resumes.
So my current solution, after "fixing it" with the 3 seconds power button push, is to NOT connect with the app to the BMS anymore. It's been days since my last fix and the battery still behaves normally. I understand it's not an option for many people, but at least you get to use the battery once again. For me it's ok since I'm monitoring everything with the Victron products anyways and manually checked the cells and they're ok, so I'm not that worried.
If anybody else has any more insight to share about this, please do, maybe we can figure this out. I still hope it's just somehow related to low temperatures and when they start going back up, everything will return to normal.
2 screenshots below with how it looks like in the app when it's normal and when the error occurs.
I figured out that my battery gets the Problem with cold Temperature right now here and me trying to load it with my multiplus now i have the battery inside let it become warm and try again but in the end i think i will switch to another bms which is More Rock solid as im ok with my bms to prevent loading when it is too cold but Not to get into a unrecoveravle state
I had similar problems last year when I had my cells in my shop. I thought keeping them in the insulated shop inside my barn would be enough to keep them from getting that cold, but it wasn't. I ended up putting them inside a chest freezer and then put at temperature controlled light bulb in the freezer to warm everything up. After I did that, never had any issues.
