272ah 4s 12v Battery Failed Cell

[Bgames]

So I built my first DIY Lifepo4 battery for my camper and everything was good until Sunday when one of my cells started reading .222v. I tried to put the whole pack on charge overnight with no success. They have a warranty on them but I leave for a 2 month camping trip around the US in about 5 weeks.

I can't seem to find the Lishen 272ah cells anywhere that will arrive in time, but found plenty of 280ah cells. Would there be a problem with adding a 280ah into the pack (leaving the BMS capacity to 272ah)? Beyond that I'm at a total loss....

Thanks in advance

 

[NVS]

You should be fine just top balance the cells and rebuild the pack.

 

[Alkaline]

I'm pretty sure at .222 you have killed you cell, what bms were you using? Daly? Daly seems to be causing all the issues and fires I heard they also don't cut of the cell at 2.5 volts like the other bms.

 

[MisterSandals]

everything was good until Sunday when one of my cells started reading .222v.

So this just suddenly happened or is there an event (or neglect) that took place?
I have a lot of cells and have never had one just go from 3.2V to .222V.

It that measured at the cell with a meter or is that reported in an app?

Have you cleaned and tightened the connections on that cell?

 

[Bgames]

This is my BMS:

4 Cell BMS (12 Volt) – Overkill Solar

BMSs for 4 cell LiFePo4 battery assemblies.

overkillsolar.com

So more history... Cell #4 in my pack has always been a little "off" since I built everything last July. The BMS is always having to balance that cell in comparison to the others. It was off as much as .15v as compared to the other 3. I didn't really think anything of it since the BMS was essentially doing its job. I'd just taken the whole pack off my small trickle charger (yes it's Lifepo4 compatible) from storing it in my basement over the winter. I brought it upstairs to go put it back on the camper and reconnect my shore power connection (have a dedicated 30amp power pole for the camper) but got busy and let it sit for 2 days until I finally had time to go put it on, got it all hooked up and connected my phone to the Bluetooth and there it was, dead as a doornail. No obvious swelling, all terminals are tight, but not overtightened. All wire connection joints are solid.

I apparently just have the absolute worse luck in the world!!

 

[Alkaline]

Where did you buy your cells did they come with a warranty?

 

[MisterSandals]

Just out of curiosity, what are the voltages of the other 3 cells?

 

[HRTKD]

Take the pack apart and move the problem cell to a different position. While the pack is apart, use a multimeter to verify the voltage of each cell at the cell terminal (not the bus bar, fastener or the balance lead ring terminal).

It's possible that the process of moving the battery around caused something to come loose.

 

[Bgames]

Bought them from Shenzen Basen, they have a 5yr warranty. I had a similar thought on letting the BMS charge everything back up and then taking the pack apart to see if the voltage still drops overnight. When I went to lift the pack out of the box, I noticed the cell is bulging on the sides (not a great sign). I'll update the individual cell voltages once I have everything taken apart.

 

[Alkaline]

Well good luck on the warranty from ali seller, I think they'll will offer you $10.00 off your next order as the resolution...

 

[Bgames]

This far the mfg has been asking all the generic questions that have been posed here, or that I already thought of. I figured I'd upload a pic of the BMS and the bulging cell just to see others opinions on whether that much bowing is/could be considered normal or not. Right now the BMS is super pissed off cuz I keep unhooking things and moving stuff around.

 

[Alkaline]

Bruh,

You ain't going to get anything back form them, just buy another cell and take whatever baloney discount they give you. We all accepted this when we buy from Ali sellers.

Ask anyone on the forum that has had problems, that is how it goes. That, or you can pay 1.5-2x the price and buy grade A that come with the green/yellow spreadsheet.

Chinese warranty = used toiler paper, especially if the are based over seas.

For everyone else, buy some spare cells because these are grade B.