Beware? Shenzhen GTKPower batteries - Aliexpress lifepo4

[mhanawalt1]

Contacted seller last week with results of the battery break down and inspection. Asked for partial $ refund or 4 additional (105a) cells to compensate for the deception.
Received this response from seller today.

"please full charged it to be 4.6V and discharge it be 10V , then you can get the full capacity "

 

[mhanawalt1]

Seller today: ""it is impossible it is only 96ah for each battery"

My response: "Are Chinese amp hours different than USA ah ?? I'll send photos if you provide a link or email address.

 

[mhanawalt1]

I rebuilt each battery pack with copper bus bars & cable lugs. Top balanced @ cell level than @ pack level.
Have cycled each pack several times and am very pleased with the results. The cells now stay stable and together through out each cycle
and I have a slight increase in capacity in each pack. Got no indication of a bad cell.
Thank you so much for the advice I received.

 

[Trompicallo]

hi everyone.
read the post for reasons and its solved,but as i can sleep,i want to comment two things.
first,i read up there that its useless always charge to 80%,but its a good measure if the battery will stay unused for month,never storage it at 100%.
but if you always charge it to 80% and set the BMS to balance only in charge,it will almost never balance the cells.
The specific BMS of this thread have the 2 options,balance while charging,at the end of the charge,or the second mode,"static" that will balance always,and its the mode the OP needed to use,to solve the huge imbalance,or if he will charge to 80% SOC.

last one,OP said something about the various names of the company,all starting by Shenzen,but i hope you know Shenzen is the region name,where almost all the electronic industry is located in China,and lots of company names started with Shenzen,just in case.
congrats for solving the problem.

 

[LeRoy Christensen]

Yes I do get that cell imbalance @ 3.0 at low end and 3.45 on high end. Cells come in to balance as a pack, between 3.0-3.45
Above or below those values 1 cell will runaway and trigger a bms shutdown. Weird thing is, it is not the same cell in both directions.

Does not seem to be a way to contact Aliexpress directly once the dispute window has closed. Shenzen GTX Batteries does not
publish any direct contact info that I can find.
I did use the contact seller link in Aliexpress to send a message a week ago. No response yet.
Not likely I can reverse Credit Card after 6mo, but I 'll check on Monday.

Thank you for your observations - didn't want to besmirch the company with out cause.
The (3) batteries in parallel stay balanced between 30-80% soc and I use them in that range. so its not a total waste.

* In my research Shenzen Co. uses 3-4 different names on Aliexpress all the ones begining with Shenzen.

I've seen similar results with Shun Bin 400ah cells. I'm running 8 in series for a 24v system volt ranging from 23 to 28.5. In this we are getting 395ah of usage, close enough for our purposes. I believe my issues that we have encountered are from not spending weeks balancing these cells on the top end. I use a Orion Jr 2 BMS with resistive internal balancing, manufacturer insisted this is adequate for my cells. With multiple faults on charging I was not believing that statement. Being very inpatient I purchased a active balancer to help the process. Unfortunately the two did not work well together, Chinese active balancer was too slow to alter voltage, so the BMS was fighting against it. Also the active balancer works in the .1 volt range the non adjustable and BMS is what ever you set, using .01v currently. Good luck.