JK-B2A8S20P-H temperature sensor problem

[MalBurn]

I have two lifepo4 self builds, using a JK-B2A8S20P-H in each battery pack. I refer to them, very imaginatively, as BAT 1 and BAT 2.

They have been running faultlessly as solar storage since September 2022.
A few days ago while taking my usual system logs, I noticed temperature sensor T2 on BAT 1 was showing 0.00 degrees C, while T1 was showing 10 degrees.

My garage where the batteries reside, was at 10 degrees C and the usual reading on both T1 and T2 generally follows ambient.

It’s not a big deal, but when I checked BAT 2, it’s T2 sensor is also reading 0.00 degrees C and again T1 was reading ambient.

I’ve tried restarting both BMS, removing and replacing the sensor plugs and switching the sensors off and on again in the app.

T1 responds to temperature, if I hold the probe it starts to rise. T2 doesn’t respond.

I’ll check resistance later today, but it seems unlikely both probes would fail together.

Has anyone else experienced this on their JK-B2A8S20P-H?

 

[tjstepanian]

Interesting... I am having a similar issue where I have 16S- lifpo4 batteries using a JK-B2A20S20P BMS running since June of last year. Just a couple days ago I experienced T2 reading of 0 while T1 seems to be working using the same measures you did.

I am receiving "temp sensor abnormal" from the application on my phone, unable to get warning to stop. System is running fine on a LV6845 however, I have been at 183 remaining Amp Hours (of 280 ah capacity) and will not rise while the voltage on the battery reaches 55.1 Volts. The battery bank sits in my closet in the house so I do not think temperature is the issue.

On a side note, I have a 24 volt system with the 8S- JK BMS where T2 reads 0, T1 is fine with no issues and no warnings. Just odd that T2 on both systems (48V and 24V) using JK BMS's now reading 0.

Have tried several times to contact JK BMS and they are refusing to answer or ignoring me, I keep my requests professional so no reason to ignore.

 

[MisterSandals]

T1 responds to temperature, if I hold the probe it starts to rise. T2 doesn’t respond.

where T2 reads 0, T1 is fine with no issues and no warnings.

Have either of you tried switching the sensors between the T1 and T2 ports?
I tried to read this into anything you both wrote, but could not tell that you did this.

And where exactly are your sensors placed? Pics?

And a longshot: there were a couple app updates and firmware updates. Did either of you update those?

 

[tjstepanian]

MisterSandals,

Thanks for your reply...No, I have not tried to switch the sensors because they share one connector and the connector only goes in one way. I thought about purchasing another but if that is not the problem...

T1 sensor is placed on the post of the battery, T2 is placed in between the battery bank in the center. Please correct if wrong. However, T2 reads 0 when I hold it and does not change.

As for the updates...THAT was one of the questions I had for JK BMS support. I had attempted to update the application by removing the old app and reinstalling the new, didn't seem to help (must be doing it wrong). As for the firmware, would appreciate any help or direction you could send me. Application ver...V.9.9, They came out with a new one a few days ago... Hardware version V11.XW, software V11.18H

Again, Thanks for you concern

 

[MisterSandals]

THAT was one of the questions I had for JK BMS support. I had attempted to update the application by removing the old app and reinstalling the new,

I only have a couple Overkill/JBD BMSs. They work perfectly with all the apps i have tried.
You did not mention which app you are running so that makes helping difficult too. Did you get "the application" from the app store or ??

App store shows JK JBMS app as V4.9.10 so i dunno.

 

[tjstepanian]

Did you get "the application" from the app store or ?? App store shows JK JBMS app as V4.9.10 so i dunno.

Correct from the App store, that is the version that I found a couple days ago (V 4.9.10) and tried to load. I am now realizing that JK BMS support has dropped off the edge of the world after reading multiple posts here on the forum, which explains why they have not responded. Thinking I may have wasted my money going with them. If I don't get this solved soon I may have to go with another...

 

[MalBurn]

Have either of you tried switching the sensors between the T1 and T2 ports?
I tried to read this into anything you both wrote, but could not tell that you did this.

And where exactly are your sensors placed? Pics?

And a longshot: there were a couple app updates and firmware updates. Did either of you update those?

Same for me as tjstepanian.

The sensors are tied to a single four pin plug, the pins could be removed, it would be fiddly, but I might try it
On my batteries the T2 sensors were at the bottom middle of the four cells in each battery case.
My batteries are static, firmly mounted and have had no updates.

Both of my JK's are less than four months old and both exhibited this failure in T2 on the same day.
Taking the sensors out of the case and placing each between my fingers, T1 responds, T2 does not.
Resistance of T1 and T2 looks to be good, seems the problem is in the BMS and not the sensors, but unconfirmed
My app version is V4.9.9, I might try updating. Have contacted JK support, will wait to see if they respond, so far they have asked for app data.

 

[MalBurn]

Since both my JK's failed on the same day, I starting thinking about the app being the issue, as there's only one app reading both batteries.

I got an iPhone a few months ago, I thought I'd turned off all auto updates, but having checked the app version in the App Store it's V4.9.10! and says 4d ago.
This is inline with the problem starting. Curiously if I open the "About" in the app itself it says V4.9.9
I'd checked the version after the problem began, saw V4.9.9 and thought no more of it. Looks like this might be the issue, bug in the app.

 

[ChriWo]

Hi,
I'm having the same issue since I updated the APP to the latest version (IOS 4.9.9).

I also have a Raspberry where I have the BMS connected via the GPS port. I use the venus OS from victron and here I get booth temperatures right.
I changed the temperature from +20° to -5° first on T1 and then on T2 I get the correct value on T1 and T2 on Venus OS and the BMS switched of the charging for T1 and/or T2.

So it is the APP only, the BMS is behaving Ok.

 

[MalBurn]

Hi,
I'm having the same issue since I updated the APP to the latest version (IOS 4.9.9).

I also have a Raspberry where I have the BMS connected via the GPS port. I use the venus OS from victron and here I get booth temperatures right.
I changed the temperature from +20° to -5° first on T1 and then on T2 I get the correct value on T1 and T2 on Venus OS and the BMS switched of the charging for T1 and/or T2.

So it is the APP only, the BMS is behaving Ok.

That's good to know, if the sensors are working via the gps port, it has to be the app.

I'd be interested to know what version number you see if you look under "History of Version" from the Home screen list. On mine In the "About" it says V4.9.9, but in "History of Version" it says V4.9.10 and also in the App Store the loaded app is IOS V4.9.10, not V4.9.9

In any case I'm happy enough to leave it be and see if it's sorted out on the next update.

 

[ChriWo]

I have the exact same version information

 

[MalBurn]

I have the exact same version information

Thanks for that.
Well, that confirms it as a bug in the V4.9.10, at least we know there's nothing wrong with the hardware.

 

[MalBurn]

Thanks for that.
Well, that confirms it as a bug in the V4.9.10, at least we know there's nothing wrong with the hardware.

Tried using an old Samsung phone with JK BMS v4.9.7
Worked perfectly, both temperature probes indicate as they should.

I think it’s safe to say avoid upgrading the JK app to v4.9.10 on IOs

 

[tjstepanian]

I got an iPhone a few months ago, I thought I'd turned off all auto updates, but having checked the app version in the App Store it's V4.9.10! and says 4d ago.
This is inline with the problem starting. Curiously if I open the "About" in the app itself it says V4.9.9
I'd checked the version after the problem began, saw V4.9.9 and thought no more of it. Looks like this might be the issue, bug in the app.

Wow ! This is both great and terrible at the same time. This must be my problem as well.

I contacted Hankzor BMS (seller) they informed me that the NTC cable is bad. I told them it is only 3 months since I bought the BMS. They are sending this at no charge. But it seems that you guys are experiencing the same as me.

So, how do I go about getting an older version of the app ???

 

[MalBurn]

Wow ! This is both great and terrible at the same time. This must be my problem as well.

I contacted Hankzor BMS (seller) they informed me that the NTC cable is bad. I told them it is only 3 months since I bought the BMS. They are sending this at no charge. But it seems that you fuys are experiencing the same as me.

So, how do I go about getting an older version of the app ???

I’m not sure if it’s possible, but since the hardware is functioning ok, I’d say just wait for a fix in the next update.

I was worried that the cold temp protection might not work, but that’s not the case.
JK support have passed my message and pics on to their engineers, I let them know other versions of the app work, the problem being with v4.9.10

 

[tjstepanian]

JK support have passed my message and pics on to their engineers, I let them know other versions of the app work, the problem being with v4.9.10

Good news, happy you were able to contact them since I was unable for the past couple weeks.

I do have a slight issue with my bms in that everything seems to be functioning normal with the exception that my capacity (280 Ah lifepo4) never rises above 183 Ah. This became an issue at the same time. I believe (thought) it had something to do with my "temp sensor abnormal" reading. I am looking to see if there is a firmware update to load and possibly fix the issue. I have also contacted HankzorBMS store, or maybe if/when the update for the app comes in, it will fix my issue.

 

[MisterSandals]

I do have a slight issue with my bms in that everything seems to be functioning normal with the exception that my capacity (280 Ah lifepo4) never rises above 183 Ah.

You should start a new thread where we can investigate this and get it fixed.

 

[tjstepanian]

You should start a new thread where we can investigate this and get it fixed.

​

Thank you, however after reading multiple posts I believe (hope) I have the issue at hand. I have two issues​

1) "temp sensor abnormal" warning on app. I am hoping a soon updated fix to the app, will solve this issue. The warning came right after they pushed an update few days ago. (others having as well)​

2) My Ah reading, I believe (hope) this issue is the latest update pushed out by JK BMS on the app as well. I have also contacted Hankzor BMS store (seller), they seem to think it is the temp cable and they are sending me a new cable. I am checking for any latest firmware updates just in case.​

If not, I will start a new post.​

Again Thank you

 

[tjstepanian]

UPDATE !!!

JK BMS just pushed out a new update 4.10.1 an hour ago. ALL my issues are working at the moment, on 16.2 IOS.

Both temp sensors are working normally

Waiting to see if capacity rises above 185 ah.

 

[MalBurn]

UPDATE !!!

JK BMS just pushed out a new update 4.10.1 an hour ago. ALL my issues are working at the moment, on 16.2 IOS.

Both temp sensors are working normally

Waiting to see if capacity rises above 185 ah.

Great news thanks, just done the update and my T2 temp issue is resolved too

If you read these forums, Nice work Jikong much appreciated!

 

[fdom]

You should have got a low temp warning and a charge disconnect if the temp sensor or the BMS temp reading would have been the prob, shouldn't you?

 

[MalBurn]

You should have got a low temp warning and a charge disconnect if the temp sensor or the BMS temp reading would have been the prob, shouldn't you?

Probably so, I didn’t suspect it was the app, since as far as I knew it hadn’t been updated. All auto updates now turned off on my phone!
You live and learn.

 

[Noordsolar]

The Apple app store lists 4.9.10 as "add some functions " . Has anyone found any new features with this version?

 

[MalBurn]

The Apple app store lists 4.9.10 as "add some functions " . Has anyone found any new features with this version?

Can’t say I’ve noticed anything, will have a closer look.

 

[MalBurn]

Can’t say I’ve noticed anything, will have a closer look.

No nothing has changed as far as I can see