Kit build woes continue...

[peasjam]

So, after hearing from BMS battery that I probably killed the BMS with the charger I had my new bits arrived today; a new BMS and a 400W 48.5v 6A charger.


I stripped down the battery pack. This is the BMS currently installed:

This is the 48v 16Ah 16 cell LiFePo4 battery pack from BMSbattery.

Aside from the large B- and P- terminals there are 17 inputs. Starting at 0, 0-15 connect from the negative of each cell (so 16 in total). The final (17th connection, marked as 16) takes a positive connection from one of the cells.
I'm a bit stumped with the 17th connection, I was just expecting 16... and the new BMS:

.. does only have the 16 connections, marked B1 to B16 that I was expecting... So, not sure how to resolve the two to be honest.

Having stripped the battery pack outer off to get at the BMS I have found another issue. 15 of the cells all read 3.32v, one of them 0.04v. So... looks like a dead cell in a brand new unused battery
I'm wondering if actually the BMS is fine and it's this dead cell that is preventing charging.

Arrrrrgh!

 

[NRG]

Could be, a cell at that voltage is effectively dead. You could try and resurrect it by charging the individual cell at a low C rate whilst monitoring it....it may recover but will always be suspect. With 16 cells you will have 17 cells wires....two cells would be three wires so always one extra.

 

[banbury frank]

Hi

peasjam

I build these battery's in my workshop in Banbury we buy in the cells and the BMS and assemble hear in the UK Best battery out there



NOT a diy job one mistake and BANG and A fire

You can bring to Banbury but there will be a charge off £200
that includes a new cell

You need to bring the controller as well as the charger so we can fit all the right cables and connectors

Please call me we can do it weekends while you wait it takes about 3 hours



Frank

 

[Cyclezee]

Hi Peasjam,

Apart from the dodgy cell, I have to say that the soldering is not the neatest I have seen. I hope that the rest of the assemby is better quality than that.

 

[peasjam]

Could be, a cell at that voltage is effectively dead. You could try and resurrect it by charging the individual cell at a low C rate whilst monitoring it....it may recover but will always be suspect. With 16 cells you will have 17 cells wires....two cells would be three wires so always one extra.

I wondered briefly about trying the phone charger method often mentioned on endlessSphere, but it seems to be for resurrecting cells at or around the 2v mark. I think this one is fully dead to be honest.

Not sure where the 17 wire goes on the new BMS then... I only have two 8 pin sockets on it. Still, when I get the new cell sorted I might find that the original BMS is fine.