Anyone else had issues with JK BMS dropping Bluetooth connection mid-charge?

Been having a frustrating time with my JK BMS (the 200A 8S unit I picked up from AliExpress back in March) losing Bluetooth connection to the app almost every time my Victron MPPT kicks into absorption. Doesn't drop during bulk, just seems to happen right around that transition. Running a 280Ah LiFePO4 pack I built myself from EVE cells.

I've tried it on two different Android phones and the connection just vanishes — sometimes comes back after a minute or two, sometimes I have to walk up to the unit and physically get within about a metre before it'll reconnect. The BMS itself seems to be functioning fine, cells are balancing nicely and the pack is performing well, so it's not a safety concern as such. Just annoying when you're trying to log data.

Has anyone else seen this? I'm wondering if there's some kind of interference from the MPPT or the inverter during that charge phase, or whether it's a known firmware bug. I'm on firmware V11.25 — I did see mention of a V11.27 update floating around but couldn't find a reliable download link. Any pointers would be brilliant.

Mine does this too but honestly I've just accepted that the JK app and I are in an abusive relationship — I check in, it ghosts me, I go back anyway.

One thing that actually helped on my boat install was moving the BMS away from anything with a switching power supply nearby; mine was right next to the Victron MPPT and the interference was doing my head in. Worth trying a Bluetooth range extender or just using the RS485 cable connection instead — far more reliable once I ditched the wireless faff entirely.

Also worth checking you're on the latest JK firmware; mine went from catastrophically unreliable to merely occasionally unreliable after updating, which I'm choosing to call progress.

Same unit here, running it on my shepherd's hut build. What fixed it for me was disabling the "Bluetooth auto-sleep" option buried in the BMS settings — it's not obvious in the app but it's under the advanced parameters section. The JK drops the radio to save power during high-current events unless you turn that off.

Also worth checking: if your Victron MPPT is on the same DC bus, the switching noise can interfere with the BLE signal at certain absorption voltages. I added a ferrite ring on the BMS balance lead harness and it made a noticeable difference.

@MarineKaren the "abusive relationship" is accurate but there are workarounds before accepting defeat — the hardware itself is solid once you stop relying on the Bluetooth for anything critical and use the RS485 port instead if your setup allows it.

Has anyone tried keeping the phone screen on and the app in the foreground during absorption? I wonder if it's the phone dropping the BLE connection rather than the BMS itself — Android is notoriously aggressive with background process killing.

On my narrowboat setup I've got a Raspberry Pi running a Bluetooth bridge to keep a persistent connection, which has been rock solid. But that's maybe overkill for most people.

@AndyGraham — did disabling the auto-sleep fix it completely or just reduce the frequency? Curious whether the BMS is still logging data correctly in the background when it drops, because that's my main concern — I want to know what's happening to cell voltages during that absorb phase specifically.