Help Fogstar 280Ah battery issue in Spain

[Cush]

Some use the xiaoxiang app. in the settings you can change the balance on charging toggle switch and it may balance without charging. You may void your warranty though. Otherwise draw a small load that doesn’t stress the lowest cell is the way to go. Good luck.

 

[Raul]

How would it get that unbalanced as it is a very new battery and is charged by Orion XS and a solar controller with lithium profile?

If it's a new battery, it is possible that's been shipped out, unbalanced. With use the deviation just grew due to lack of balancing time. Balancing takes place when you spend time on absorb.
If you get to absorb and have loads on that time, large enough to discharge rather than charge, the weaker cell will never have a chance to catch up, and the cycle repeats.
You need to spend time on absorb, and observe the voltage deviation. It needs to come down from 299mV to well under 50mV when you can really use it properly.
Small current, and patience.
I had the opposite, one really full and the rest not so full. Was triggering the bms. So I opened the box, identified the cell with higher voltage, and bled manually with a car bulb and two wires directly on the cell terminals.
I managed to bring it down to a level where the bms took over the small balancing.
Now, all batteries I build they have active balancing, not just the small resistors.

 

[MichaelT]

If it's a new battery, it is possible that's been shipped out, unbalanced. With use the deviation just grew due to lack of balancing time. Balancing takes place when you spend time on absorb.
If you get to absorb and have loads on that time, large enough to discharge rather than charge, the weaker cell will never have a chance to catch up, and the cycle repeats.
You need to spend time on absorb, and observe the voltage deviation. It needs to come down from 299mV to well under 50mV when you can really use it properly.
Small current, and patience.
I had the opposite, one really full and the rest not so full. Was triggering the bms. So I opened the box, identified the cell with higher voltage, and bled manually with a car bulb and two wires directly on the cell terminals.
I managed to bring it down to a level where the bms took over the small balancing.
Now, all batteries I build they have active balancing, not just the small resistors.

Not sure if understand all that but it's only had a couple of cycles so maybe needs more to balance it out.

 

[Raul]

Not sure if understand all that but it's only had a couple of cycles so maybe needs more to balance it out.

Probably that battery never seen a proper balancing before was shipped. If it was assembled with cells at different state of charge, the battery needed a full charge to highlight the balance issue, before shipping.

When you assemble a battery, those cells need to be equally charged before assembly.
This is not the first time, some batteries are just badly matched and expect the bms to do the balancing.

Or, hope not, the weaker cell has a problem.

 

[daveclare]

They had theirs fitted by a company near Hereford. Their customer service has been excellent. But I heard them say that Fogstar are not quick in getting back to people.

^{_{Subscribers  do not see these advertisements}}

 

[AdrianChen]

Probably that battery never seen a proper balancing before was shipped. If it was assembled with cells at different state of charge, the battery needed a full charge to highlight the balance issue, before shipping.

When you assemble a battery, those cells need to be equally charged before assembly.
This is not the first time, some batteries are just badly matched and expect the bms to do the balancing.

Or, hope not, the weaker cell has a problem.

Hi Raul - Thinking ahead to when I get a similar problem! Could I just set absorbtion on the charger to say 13.3v, and start a 1.5hr absorption cycle?