JK BMS failure

[MKalman]

JKBT 7S-20S 120A 0.6A Smart Active Balance BMS Board

JKBT 7S-20S 120A 0.6A Smart Active Balance BMS Available at Sriko Batteries, the top online electronics store for electronics. We deliver the lithium-ion battery in the US. We have the best BMS for lithium-ion batteries.

srikobatteries.com

This BMS, ordered it, installed it, BMS turns on and it shows all cells and lets power through, but what blows my mind, is if the cell voltage meets the minimum or maximum cell voltage, the BMS does nothing.

Has anyone experienced this? Is this abnormal? Is there something I'm missing?

 

[LydMekk]

Post photos of your parameters setup.
You have set it up and not just turned it on yes?
It needs to be programmed.

 

[MKalman]

Post photos of your parameters setup.
You have set it up and not just turned it on yes?
It needs to be programmed.

Yes, all the parameters are set up, not just turned on. I'll get a picture as soon as I get back

 

[Checkthisout]

Please don't post this. I just installed one of these to replace a daly bms that failed.

I have yet to activate but will tommorrow.

Please tell me it's user error and these things aren't junk too.

 

[MKalman]

Going back to the JBD BMS which lasted me one year. Serious considered the K9 but not sure how hard it would be to configure

 

[MKalman]

Please don't post this. I just installed one of these to replace a daly bms that failed.

I have yet to activate but will tommorrow.

Please tell me it's user error and these things aren't junk too.

I am praying this is the case, but it really doesn't look so on my end.

 

[Horsefly]

I'm curious why you bought from that particular web site. I really know nothing about them, so I don't want to say anything bad about them. However, to my knowledge they are not the "root" source of the JK BMS, which I am fairly certain is Hankzor BMS store on Aliexpress. If my understanding is correct, the place you bought them would have (hopefully) purchased them from the Hankzor store. I guess you get a shorter shipping time in the U.S., but it is not clear to me how old the stock is you are buying from.

I have three JK BMS equipped batteries that are all working fine. However, I did buy one in May of 2022 that had a design flaw (I posted about it here) that caused me all kinds of grief. After becoming convinced they had found and corrected the issue(s), I bought a new one from Hankzor and all has been great since then.

Again, I'm not trying to blame the store, as I know nothing about them. I am only suggesting the stock they may be selling may be old, and may have been from the same problematic stock that I saw in 2022.

 

[MKalman]

I'm curious why you bought from that particular web site. I really know nothing about them, so I don't want to say anything bad about them. However, to my knowledge they are not the "root" source of the JK BMS, which I am fairly certain is Hankzor BMS store on Aliexpress. If my understanding is correct, the place you bought them would have (hopefully) purchased them from the Hankzor store. I guess you get a shorter shipping time in the U.S., but it is not clear to me how old the stock is you are buying from.

I have three JK BMS equipped batteries that are all working fine. However, I did buy one in May of 2022 that had a design flaw (I posted about it here) that caused me all kinds of grief. After becoming convinced they had found and corrected the issue(s), I bought a new one from Hankzor and all has been great since then.

Again, I'm not trying to blame the store, as I know nothing about them. I am only suggesting the stock they may be selling may be old, and may have been from the same problematic stock that I saw in 2022.

So, I don't know whether or not this is the case. All I know is SRIKO sells a lot of BMS so I doubt their stock is that old.

On the other hand, the BMS looks identical to the one on the https://www.aliexpress.com/item/100...promoteWysiwyg_6000463681370.1005003684294744 official store. The name is the same, the model name is the same, the same sticker, same everything.

I'm not sure, I even considered getting the BMS from the Aliexpress store again, but the thing is, if it happens again I'd be shooting myself in the foot. My JBD BMS crapped out a few months ago with a short circuit error though there was no short circuit and stopped working entirely.

Moving forward, does anyone have any bad experience with JBD or was that one a fluke as well? I'm concerned. I just want something stable moving forward.

 

[ChrisG]

So, I don't know whether or not this is the case. All I know is SRIKO sells a lot of BMS so I doubt their stock is that old.

On the other hand, the BMS looks identical to the one on the https://www.aliexpress.com/item/100...promoteWysiwyg_6000463681370.1005003684294744 official store. The name is the same, the model name is the same, the same sticker, same everything.

I'm not sure, I even considered getting the BMS from the Aliexpress store again, but the thing is, if it happens again I'd be shooting myself in the foot. My JBD BMS crapped out a few months ago with a short circuit error though there was no short circuit and stopped working entirely.

Moving forward, does anyone have any bad experience with JBD or was that one a fluke as well? I'm concerned. I just want something stable moving forward.

I just switched from JBDs to JK to simplify everything. My JBD was 100% stable but after adding heltech active load balancing boards and a voltage controllers for them they got messy looking and had to do many tweaks of terminals and connections.

 

[Alarchist]

This BMS, ordered it, installed it, BMS turns on and it shows all cells and lets power through, but what blows my mind, is if the cell voltage meets the minimum or maximum cell voltage, the BMS does nothing.

Has anyone experienced this? Is this abnormal? Is there something I'm missing?

So it doesn't cut the load when a cell hits 2.75v or 3.6v?

Were you just testing the BMS limits, or do you have a charge controller that can't be set to keep the cells within the BMS limits, so you rely on the BMS shutting off power?

Also, why are you balancing at 3v that won't work. It should be 3.4v +

 

[MKalman]

So it doesn't cut the load when a cell hits 2.75v or 3.6v?

Were you just testing the BMS limits, or do you have a charge controller that can't be set to keep the cells within the BMS limits, so you rely on the BMS shutting off power?

Also, why are you balancing at 3v that won't work. It should be 3.4v +

Not at all, nothing

And balancing works at 3 but I’ll change it

It does nothing at 2.75. Victron multiplus sucks more power or charges beyond

 

[740GLE]

Did you try adjusting the low voltage disconnect to say 2.8v, save the settings and see what happens?

The BMS is a last line defense, good thing you caught it before damage could occur.

 

[MKalman]

Did you try adjusting the low voltage disconnect to say 2.8v, save the settings and see what happens?

The BMS is a last line defense, good thing you caught it before damage could occur.

I don’t think I did. I caught it when one of my cells was 2.5V. I’m not going to lose sleep over it but I was pissed.

If 2.7 and 2.75 don’t do anything, it’s garbage.

 

[Checkthisout]

I don’t think I did. I caught it when one of my cells was 2.5V. I’m not going to lose sleep over it but I was pissed.

If 2.7 and 2.75 don’t do anything, it’s garbage.

Silly question.

Did you double-check the wiring?

 

[MKalman]

Silly question.

Did you double-check the wiring?

Yes. The two pigtails to the main negative other two to the negative on the battery case. All cell voltages showing properly.

 

[Alarchist]

Not at all, nothing

And balancing works at 3 but I’ll change it

It does nothing at 2.75. Victron multiplus sucks more power or charges beyond

Balance may come on at 3V, but it wont actually balance the cells, it'll unbalance them until they hit the rising voltage knee around 3.4v.

Is it possible you blew the mosfets? Over current charge/discharge, multiple short circuits / connecting inverter without pre charge?

*Edit - did the BMS ever disconnect?

 

[MKalman]

Balance may come on at 3V, but it wont actually balance the cells, it'll unbalance them until they hit the rising voltage knee around 3.4v.

Is it possible you blew the mosfets? Over current charge/discharge, multiple short circuits / connecting inverter without pre charge?

None of the above