JK BMS suddenly having setting issues

[ShockinglyAverage]

I’ve had this BMS running for over a year. Last year I put the van in storage and eventually the voltage got low enough that the BMS shut itself off. When I got the van I charged the battery enough to be able to turn the BMS back on. Everything went back to normal. Well a couple nights ago it got below freezing so the under temp protection kicked in. Later in the day, after the temp rose above the recovery setting it still wouldn’t turn back on. I went into the settings and noticed everything is now at really weird values. No matter what I change, everything reverts back to these (pics) values after closing and reopening the app. And some things when I try to change I get the “sensing failure” message. I know some thing can’t be changed before other (I.e. trying to set the ovp before setting the recovery) so it’s not that. Any idea what’s going on? I’ve searched all over and I can’t find any threads that match this.
Hitting the preset tabs for the 3 different battery chemistry at the top doesn’t change anything.

This is the old style JK not the newer inverter ones.

 

[Shane_UK]

I’ve had this BMS running for over a year. Last year I put the van in storage and eventually the voltage got low enough that the BMS shut itself off. When I got the van I charged the battery enough to be able to turn the BMS back on. Everything went back to normal. Well a couple nights ago it got below freezing so the under temp protection kicked in. Later in the day, after the temp rose above the recovery setting it still wouldn’t turn back on. I went into the settings and noticed everything is now at really weird values. No matter what I change, everything reverts back to these (pics) values after closing and reopening the app. And some things when I try to change I get the “sensing failure” message. I know some thing can’t be changed before other (I.e. trying to set the ovp before setting the recovery) so it’s not that. Any idea what’s going on? I’ve searched all over and I can’t find any threads that match this.
Hitting the preset tabs for the 3 different battery chemistry at the top doesn’t change anything.

This is the old style JK not the newer inverter ones.

Exactly the same for me. I went to check the temps were OK a couple of days ago to make sure the low temp charge protection is set correct due to current cold weather in UK and the App shows totally incorrect values for both of my BMS's. It 'seems' to be a APP issue loading correct values because even though the app shows OVP at 1.2v, I'm still online at normal LifePO4 voltages. Note the cell voltage readings are still loading correctly, it's just ALL the users customizable settings are wrong as per the OP's screenshots. I've tried changing the settings and the BMS confirms the change with a beep, but when the app is opened again it's still showing incorrect. Never had this before in 18 months I've been operational, must be a bad App update?

 

[ShockinglyAverage]

Well I’m glad it’s not just me at least. Yep, yours is behaving identical to mine. Still seems to be operating correctly (even outside of the weird parameters it keeps resetting to) and all the cell voltages are normal. Really hoping someone with jk can see this and comment on it.

 

[Shane_UK]

Note BMS model is JK-B2A24S20P, app version seems to be v4.30.0. Version seems to be from 1 week ago according to Apple App store

 

[OffGridForGood]

Exactly the same for me. I went to check the temps were OK a couple of days ago to make sure the low temp charge protection is set correct due to current cold weather in UK and the App shows totally incorrect values for both of my BMS's. It 'seems' to be a APP issue loading correct values because even though the app shows OVP at 1.2v, I'm still online at normal LifePO4 voltages. Note the cell voltage readings are still loading correctly, it's just ALL the users customizable settings are wrong as per the OP's screenshots. I've tried changing the settings and the BMS confirms the change with a beep, but when the app is opened again it's still showing incorrect. Never had this before in 18 months I've been operational, must be a bad App update?

exactly this ^^^^^
I have 8 JK BMS's - I build two packs per year.
My most recent pack build, I have this exact issue - the APP lets me change the settings, and accepts - even displays the new settings correctly until you leave the APP and come back to check later, then all the parameters look like they are messed up! (1.2v !! when would this be correct setting??)
BUT it is just in the APP - the pack runs based on the settings I input, and has been working correctly with the other packs in the ESS.
Scared the Cra@#$#p out of me the first time I saw those values though. Ordered some JBD BMS's to try...

 

[ShockinglyAverage]

I just thought I’d update this thread. I remembered that on my phone I don’t have it set to automatically update apps, so it still has an older version of the app installed than the up to date version on my systems iPad. Sure enough, the older version still displays everything correctly. So this is definitely a bug with the latest app update. Hoping they know about it and get it fixed ASAP.

 

[OffGridForGood]

That makes sense, because I didn't have this problem until I up-dated from the older app on my phone.

 

[ShockinglyAverage]

Just thought I’d update this in case anyone else comes across it and also to update those already involved: The latest update seems to have finally fixed the issue. Make sure you turn off automatic updates so this doesn’t happen again.

 

[OffGridForGood]

The latest update

do you mean from JK ? do you have the version number handy for reference? - there are a lot of different versions flying around from various sources...

 

[Shane_UK]

Just thought I’d update this in case anyone else comes across it and also to update those already involved: The latest update seems to have finally fixed the issue. Make sure you turn off automatic updates so this doesn’t happen again.

I checked again today and the update fixed it for me too., v5.0.0

 

[HarryN]

A BMS is designed to be the last line of defense to prevent a disaster for when the conventional systems fail.

They are not meant to be the first line of defense to keep a battery from being operated out of the temperature range in the data sheet, even though people use them that way.

The more correct approach is to do "whatever it takes" to keep them at 5 C or warmer. Even if that means having a heater of some kind.