JBD BMS turned off and will not come back on.

[IGTP]

Equipment--
Two MppSolar LV6048, JBD BMS AP20S003-L20S-200A-B-U, 16 280AH Lifepo cells, 36 "Super El-Cheapo" 240W used panels from SanTan Solar. The panels are configured in 4 groups (1 for each solar controller input). 3 panels in series with 3 of those strings in parallel (adds up to around 100VOC and around 25A max per group. All equipment (except panels) are kept in climate controlled conditions.

Long story short--
I've been gathering and assembling this equipment for 2 years or so with "Life" interrupting numerous times, so the equipment is new (except panels), but dated. I've learned much lurking here for those years.

Short story long--
I finally got everything together and fired it up. Ran equipment with moderate loads for 48 hours, monitored with Watchpower and saw no glaring issues.

This morning (Oct 25, 2023), had a look at the BMS using the Overkill app. Every thing looked fine except "Total Battery Capacity" was set to 50000ma. Decided to raise that in small increments on the way to 280000, so I started by setting it to 100000ma.

Immediately after tapping "BMS write" the contactor began clicking on and off. I let it continue for a few seconds since it is not unusual for this equipment to make a few clicking noises when a change is made. I soon set the Battery Capacity back to 50000ma and the clicking stopped. Unfortunately, it stopped in the OFF position and, after many hours scouring these forums and all other web sources I can find, I have been unable to turn it back on. The BMS is still alive. I can view and change settings via the Overkill app.

I disconnected the cell monitor connectors and let the BMS sit without power for 30 minutes. Reconnected the plugs and I was greeted by a few beeps, but still no contactor action.

After a few back-and-forths between the Overkill and XiaoXing apps, the Overkill app now opens with a message stating "NTC Sensor is in an error state and needs to be repaired". More Info on the message says they may be open, they may be shorted. You can work around the problem by disabling them. So, I unchecked them in the app, but have no idea where they might be on the BMS. There are none on the battery cells. Unchecking made no difference.

At the top of the Home page, there is an "Alarms" indication about temperature. It displays Temp sensors 1, 2 and 3. All read 75.5 F +/- 1 degree (I don't think room temperature qualifies as a temperature issue when the High and Low temp settings are 158 and 34F). One thing I did notice was that before I made the change, NTCs 1,2 and 3 were checked. After the change, it was 1, 5 and 6. Anyway, I can find no way to reset them, or anything else.

So I'm dead in the water for now. Any ideas would be most appreciated.

Steve

 

[sunshine_eggo]

Important that you always read from the BMS first.

No reason to "sneak" up on the capacity.

I believe you can deselect temperature sensors to inactivate them in the BMS. I would inactivate all of them.

 

[IGTP]

Thanks for the reply, eggo.

"Important that you always read from the BMS first."

--OK.

"No reason to "sneak" up on the capacity."

--Perhaps, but doing so certainly should cause no harm.

"I believe you can deselect temperature sensors to inactivate them in the BMS. I would inactivate all of them."

--That was the first thing I did when I saw the error message.


More info--
It finally got through my head that the black wire with the black bulb-thingy on the end was an NTC. In my defense, my installation had hidden the labeling on the top cover. Weak, but true. I disconnected everything from the BMS so I could access the NTC connector. It had a blob of flexible sealant holding it in so once the was removed I got the NTC disconnected. Quick test at room temp shows 10 or so ohms. Ice water drives resistance up and heat drives it down. Seems to function, but I have no idea what the nominal resistance at room temp should be. Others have mentioned that there may be one or two more on the BMS board. I am clueless about where to start looking.

Reconnected the NTC, then everything else. The contactor came on for about a second, the off again, so something woke it up for a moment, but no actual progress was made.

I've ordered a UART to USB adapter so I can use JBDtools. The story goes that not all functions and settings are available on the app.

Until then, I hope more help comes my way.

 

[MisterSandals]

The story goes that not all functions and settings are available on the app.

You need to buy the $6 app. Optionally, the free Overkill app has full functionality and works with most JBD BMSs (all 5 of mine).

If you did a write without a read first, you probably wrote a lot of bogus data to the BMS.
I do not see a way to reset the BMS but you should look over your settings closely.
Or post screenshots of settings and we can compare to our settings.

 

[IGTP]

Sorry for the delay getting back to you. I decided to use the downtime to move some things around to have better BMS access. I saw your reply and put it all back together.

A double "Aha!"

#1 What you said makes perfect sense. I sent bogus info.
#2 I now understand what eggo was trying to tell me.

As far as the app goes, I've read so much in the last day that it is a blur. But, if I got the gist of the apps, the $6 one was for Iphone. I'm probably wrong, but if not, I don't have one anyway.

Screenshots attached.

Thanks

 

[IGTP]

BTW..

It is interesting that each time I connect with the app or change pages, the app says "getting BMS data" or "reading BMS" with no intervention from me.

 

[sunshine_eggo]

Relay is open when this screen is displayed?





If that's the case, the BMS is signalling both charge and discharge are allowed. If you can't charge/discharge, I would conclude a faulty BMS.

 

[IGTP]

Eggo, yes to your question.
I'm holding out hope that a setting--currently not visible to me--is the culprit.

 

[MisterSandals]

Eggo, yes to your question.
I'm holding out hope that a setting--currently not visible to me--is the culprit.

What happens if you hit any of the yellow reset buttons, especially the top one. Or toggle either of the switches off and on?

 

[IGTP]

Both Charge and Discharge toggle on and off. Tried the available resets in all four combinations of on and off. Other than the app and the BMS chatting, nothing else happened.

I had called it a day and disconnected the cell connectors from the BMS. I reconnected them to address your questions. There were two short beeps as it powered up and the contactor turned on for a second, then back off. The same thing happened after testing the NTC earlier.

 

[Brett V]

are you sure the relay is getting voltage? maybe the BMS is working fine but the relay has an issue. Measure what’s happening on the coil.

 

[IGTP]

Thanks Brett. The contactor does briefly energize when first powering up, so I'm fairly confident the issue isn't electrical or mechanical. It really looks like something software-wise is inhibiting it.

I hope to have a USB to UART adapter in hand Saturday and, if it works, I'll be able to have a better view of the settings. There are a few that the Overkill app for Android does not display, FET ctrl being one. If that doesn't help, well then I guess it will be time for some disassembly.

Steve

 

[deonbez]

I am having a similar issue.

It seems to only happen after a cell over voltage (OV) occurred and protection (OVP) kicks in. The BMS OVP is set as 3.6V and release at 3.53V.
I expect the relay to disconnect the battery from the inverter but then reconnect once the cells are below the release voltage.

The disconnect happens as expected but the reconnect does not happen even with all cells being below 3.45V when balancing closes.
I can toggle the Charge / Discharge switches on the app but relay does not click connect/disconnect almost like in an override state.

The only way I could get the JBD BMS out of this mode, was to disconnect the inverter and connect a charger to it. As soon as the charger is connected via a series recharge resistor, the relay clicks and it seems as if the expected release is triggered inside the BMS. From this point on all is working again as expected.

To overcome/work around this, I adjusted the inverter to boost charge at 55.2V and float at 54V. The cells are then balanced as expected and OVP does not occur ?

I have tested 2 BMSs with similar results.

To me it looks like a firmware issue not releasing at correct cell voltages.

Any insights will be greatly appreciated.

 

[IGTP]

It's been a long week and the news is not good.

Finally got the USB to RS485 adapter. The BMS only says the password is incorrect. The Overkill PC app says it is resetting the password. When I try to read the BMS again, password is incorrect. I'm still pretty sure this is a software and not a hardware issue and I'm reluctant to give up without a firmware reload.

The Xiaoxiang PC app appears to be able to do a reload. Only problem is finding the file to do it with. Many horror stories are available on the interweb about reloads gone bad using the wrong file. I'll save that adventure for another time.

But, the password thing raises an interesting point. Sometime in the recent past, JBD introduced a password system to limit access by Bluetooth. You know, to keep people like me from doing what I did, or to keep someone from messing with your settings. I find that a bit humorous actually. How many times has a bad guy been caught sniffing around someone's solar gear for an open BMS Bluetooth connection? He'd have to get pretty darned close. CYA I guess.

Anyway never, in any of my trials with either of the Android Apps, was I asked for a password. Yet, the Overkill PC app does query the BMS for one. Maybe the password addition came out after mine was produced. Curious. Confusing as well.

To cover all the bases, with trusty VOM in hand, checked ALL balance wires for both continuity and proper voltage from pin to pin. Checked that I had correctly connected all of the extra balance wires. Taking Brett's suggestion, I monitored the contactor actuation voltage. I'm here to tell you that wasn't easy. The contactor is only briefly energized at power on, my VOM isn't lightening fast, nor does it have a HOLD function and it took four hands to pull it off. But, while I didn't see the precise voltage applied, there was a reading--until there wasn't.

I've spent too much time chasing this so, reluctantly, I've ordered another BMS. Same brand, but the contactor is a different design. I'll run through all of the hookup preliminaries again once it gets here.

I'm really having a hard time understanding how a simple change to my settings resulted in a bricked BMS. I do understand that I probably sent bogus info to it because I didn't read from it first. But, EVERY TIME I connect the app to it via Bluetooth, I have to wait for the BMS info to load--without me requesting it. So, if the BMS info is requested automatically by the app, how did ME not requesting it do the damage. I accept that that is the most likely cause. I just don't get it. Oh well.

Sunshine eggo, MisterSandals and Brett. My thanks to you all for your assistance. If you don't mind, I'll post again after I save the settings and BEFORE I try to make any changes to the new BMS with any app. Maybe you can steer me clear of further mayhem.

By-the-way--I did find a "PRO" version of the Xiaoxiang Android app through Randomfix's Youtube channel. I like it much better than the standard. Hopefully, it has the same functionality as the IOS $6 version. It makes no difference with my current BMS, but maybe it will with the next.

Steve

 

[IGTP]

deonbez,

That's really interesting. I don't have a stand-alone charger. Maybe it's time to get one.

My all-in-one inverters won't power-up without a battery connected. I'd sure like to try your solution.

Steve

 

[deonbez]

The Xiaoxiang PC app appears to be able to do a reload. Only problem is finding the file to do it with.

If you can share your file I can try and compare on my side to see what parameters are corrupt and if my settings are useful / applicable to your BMS.

Which version of the Windows application do you use?

 

[deonbez]

@IGTP , included is the parameter file as downloaded from my operational JBD "JBD-AP21S002-L21S-300A-B-U-R-C" BMS using the
JBD Tools V2.9-20210524. I had to rename the file with ".txt" to be able to upload it.
Just remove the extra ".txt" at the end of the file to get to the original "JBD_No2_DeonBez_20231104.fig" file name again.
I had to click the green "Read" button to read the parameters and then used "SaveFile" button to save.

Also included below for completeness a screenshot of the parameters:



Hope this helps to solve the issue with your BMS.

Blessings, Deon

 

[IGTP]

Deon,

I was just getting ready to reply to you post from yesterday. I have V2.5 and V4.3. I do not have the data file.

I'll compare your file to my settings at my earliest opportunity.

Thanks so much,
Steve

 

[MisterSandals]

included is the parameter file as downloaded from my operational JBD "JBD-AP21S002

I have 2 of this same BMS and have never looked at the parameter file. It is surprisingly user readable!
I found these values a little disturbing:

HardCellOverVoltage 3900
HardCellUnderVoltage 2000

Not sure what happens beyond the "disconnect?"for undervolt
CellUnderVoltage 2650

What happens at the "Hard" limit?

 

[deonbez]

@MisterSandals , not sure how the "Hard" limit values are enforced by hardware which are more fail safe than and the firmware implemented values. Apart from the relay disconnect, I don't know if the JBD has secondary MOSFETs to protect the cells.

On my BMS its seems as if the cell overvoltage release firmware is not working anyway.
I emailed JBD sales/support (fiona@jiabaida.com) multiple times without any response.

Would appreciate if anyone with a good / reliable connection at JBD support could share some details.