Upgrading a Shunbin pack. A look inside the box + some questions ?

[Alonsw0]

I have a Shunbin 200ah LiFePO4 battery in my van (purchased by the previous owner...).
After reading most posts here about troubles with these batteries, decided to open it up and check what's inside ?️
Pics are attached.

What I found out:
- 8 green cells. 2p4s. Hopefully 100ah each (edit: measured 178ah total with AiLi monitor. 11.5-14.3v )
- same poorly soldered BMS.
- unfortunately not connected with busbars & studs (what's the name for the connection in the pic? Laser weld?)
- surprisingly cells were balanced pretty well... All 4 were 3.22v-3.21v. I don't think they were ever manually balanced since purchased.

Now for my questions:
1. Can anyone recognize what cells are they? One had serial number with barcode: E90BD412DE5457.
2. Cells being balanced now (low voltage), does that mean same for when they're full?
3. Does the low capacity can be related to top balancing problem?
4. My thought was to try and squeeze what I can from it- replacing bms for a JBD smart bms & adding an active balancer (like the Heltec 5v). How hard is dealing with the cells & terminals with the connection type I have there?

Thanks for any help! ??

 

[Steve_S]

Hi there.

1) The barcode is no help, a QR Code would be good BUT don't count on it, they scratch them off. Shunbin uses Used Cells, seemingly upcycled EV Grade - well that's what I got anyway) The cells I and DeltaV Received from Shunbin were from aoyoupower.
2) Cells balanced at low does not mean they will be when full. honestly don't bet on it.
3) Low Cell Voltage or other things are likely causing a BMS disconnect, that will cut pack capacity.
4) YES Scrap that crap BMS !
*) Don't be surprised if the cells are NOT 200AH... several have discovered that wee trick of theirs.

The cells are Laser Welded THAT'S GOOD ! but if one cell in the bunch is off, then you have an issue. You can't do much with these, I would not remove the welded bars and tap for screws, no way. I have NO CLUE what they used for wires from the BMS to Terminal WTF Clear ? Never ever seen battery grade cables with clear - So THAT has to go as well ! I used 1 Guage Fine Strand welding cable.

Overkill Solat and Current-Connected sell the JBD BMS etc (in US so faster) and current connected has extras for the BMS as well.

Shop – Overkill Solar

This is where you can browse products in this store.

overkillsolar.com

Current Connected Store ~ Current Connected

www.currentconnected.com

Hope it helps, Good Luck.