Cells that matched, suddenly read 4.0 and 1.8 then BMS fried?? Batteries from Hell....

[the_uglydog]

Hi, I've been having issues with some server rack batteries I bought, 200ah 48v. One of them was working Ok, then all of a sudden it started showing wildly mismatched cells and shut down. BMS is fried. I opened it and tried to disassemble but many of the cells were swollen and showed signs of sparking. When I finally got it apart and tested the cells one read 3.8v and swollen, 3 at 3.2v not swollen, and others at 2.4v and 1.8v and all swollen. only 3 cells are not swollen. I've had another battery that was matched suddenly read 4.0 on one cell and 2.0 on the one next to it. The BMS shut down and shows 0 state of charge but 52.5v for the voltage and when opened I tested and all cells match perfectly at 3.2v, but the BMS showed SCP fault. I've disconnected it from the battery bank, inverter and charge controllers and tried disconnecting the cables and reconnecting them and I also tried to reset it it a few times, it still shows the SCP. I found loose crimps on the BMS to cell leads and loose connections at the cell terminals. I've corrected those but it still shows SCP fault. Could that be a short in the internal wiring somewhere? Would there be a visible burn I could see? Could the other battery have had loose connections as well and that caused it to cook?

 

[S Davis]

Are there any marks or signs of arcing between the cells? Is the blue wrap intact?

 

[the_uglydog]

The blue wrap is fine, the only signs of arcs are on the tops of the batteries, especially the corner in the first picture where the top looks burned. I'm thinking these aren't the new grade A cells they are supposed to be but maybe used and unmatched junk. Some of the other batteries reach full discharge at 51.5v, 50v and 48.5v and won't charge above 54.5v. I did find loose crimps on the BMS leads in 3 of the batteries and also loose terminal nuts.

 

[MisterSandals]

I did find loose crimps on the BMS leads in 3 of the batteries and also loose terminal nuts.

This can cause false voltage readings to the BMS and loose connections can cause heat buildup and cause a fire eventually. Were the loose nuts on the terminals that show burn marks?

Happen to have a pic of how your battery was wired?

 

[Quattrohead]

Name and shame the battery as well please, QA like that is absolutely never acceptable when you're dealing with this amount of power.

 

[the_uglydog]

This can cause false voltage readings to the BMS and loose connections can cause heat buildup and cause a fire eventually. Were the loose nuts on the terminals that show burn marks?

Happen to have a pic of how your battery was wired?

I'm not actually sure about that, when I opened the first one everything looked so bad I just wanted to disconnect it and shut down the entire system. I wasn't paying attention but it does seem that I thought it all was loose. I noticed on the second battery that had problems that the cells that were showing false readings plus a few others had both loose crimps on the terminals for the BMS and loose nuts on the studs.

 

[MisterSandals]

I wasn't paying attention but it does seem that I thought it all was loose.

Yeah, this is bad and it all is subject to confusing your BMS and creating a lot of heat on the terminals.

I'd say the cause was poor connections. You may never know more than that.

 

[the_uglydog]

Name and shame the battery as well please, QA like that is absolutely never acceptable when you're dealing with this amount of power.

Guangzhou Tianyu Communication Equipment Co AKA. Turli. These were supposed to be all brand new cells rated at 200ah. One of 6 is 200ah. The others are 179ah, 167ah, 120ah,120ah, 114 ah and one 0ah. So far they are saying I overcharged them since one cell is showing 3.8v. My system is set for a max charge of 54.5v and switchback to utility at 47v with 46v the shutdown point. Some of these shut down at 50v some at 48v the only ones that made it to 46v were the 2 that don't work now. My "Boss" wanted to save $300. over the ones from the supplier I use for everything else, so now she gets to buy a lot of new cells and 2 BMS.

 

[Quattrohead]

Those batteries are one of the worst things I've ever seen on this forum, they are an absolute shit show. You need to clean up or replace the bus bars too as they're all burnt to crap too.
Honestly I would distance myself from them and just replace them completely.

 

[the_uglydog]

Yeah, this is bad and it all is subject to confusing your BMS and creating a lot of heat on the terminals.

I'd say the cause was poor connections. You may never know more than that.

I was thinking the same thing, but I wanted some other opinions as well. I'm trying to at least get 2 new BMS and maybe some new cells, although I'm not sure I want to put in anything from them. My regular supplier can get a good price on cells for me so I may just replace the cells in 2 batteries and use the remaining cells to replace other cells that are weak in the other batteries. I have already charged all the cells individually and let them all balance and reassembled all of them. After 2 days of rain the same cells show low and the batteries are back to shutting down since one or two cells in each are weak.

 

[the_uglydog]

Those batteries are one of the worst things I've ever seen on this forum, they are an absolute shit show. You need to clean up or replace the bus bars too as they're all burnt to crap too.
Honestly I would distance myself from them and just replace them completely.

I think all of the reviews they had were fake! They are still in business but they have been removed from Alibaba. I'm going to be in Guangzhou next week, I was thinking of paying them a visit.

 

[the_uglydog]

I found out something new today as well. The cells are not Grade A as they are supposed to be, the QR code under the top insulation is missing and the BMS has a new barcode stuck over the old one.

 

[Alkaline]

Hi, I've been having issues with some server rack batteries I bought, 200ah 48v. One of them was working Ok, then all of a sudden it started showing wildly mismatched cells and shut down. BMS is fried. I opened it and tried to disassemble but many of the cells were swollen and showed signs of sparking. When I finally got it apart and tested the cells one read 3.8v and swollen, 3 at 3.2v not swollen, and others at 2.4v and 1.8v and all swollen. only 3 cells are not swollen. I've had another battery that was matched suddenly read 4.0 on one cell and 2.0 on the one next to it. The BMS shut down and shows 0 state of charge but 52.5v for the voltage and when opened I tested and all cells match perfectly at 3.2v, but the BMS showed SCP fault. I've disconnected it from the battery bank, inverter and charge controllers and tried disconnecting the cables and reconnecting them and I also tried to reset it it a few times, it still shows the SCP. I found loose crimps on the BMS to cell leads and loose connections at the cell terminals. I've corrected those but it still shows SCP fault. Could that be a short in the internal wiring somewhere? Would there be a visible burn I could see? Could the other battery have had loose connections as well and that caused it to cook?

what the heck is going on there those don't look like cells more like french fries getting mushed together. Disassemble the whole thing and check all cells!

 

[the_uglydog]

what the heck is going on there those don't look like cells more like french fries getting mushed together. Disassemble the whole thing and check all cells!

I think french fries are better! That battery with all the bad cells is disassembled and even if I tried it won't fit back in the case. I'm not going to take any replacement cells from that company, what I think I'll do is buy some new Eve cells and rebuild it myself. All of the other batteries I've already disassembled and checked all the connections, many were loose. I'll use the remaining good cells from that destroyed battery and replace some of the weak cells in a couple of the other batteries and just make the best of it. I'm going to be in China next week and I plan on visiting a couple of battery supply companies, especially Seplos, they have been helpful and have offered me a tour of their facility. The best part is my wife was able to save $300. buying these instead of the ones I wanted......... Thank God she's "always right!"