How long is a piece of straw? 3 or 4 lengths.
That doesn't tell you much, does it
The lights are probably a part from the BMS.
We do not know know how many lights are on de BMS, or their capacity.
A real indication about state of charge (SOC) is the cell voltage.
56v would suggest in S16 setup to be 3.5v per cell.
While that isn't empty, it absolutely isn't fully charged.
If you keep the charge for a few days continuous to 3.5, you might get to 95%.
What many people seem to forget is the absorption phase.
Phase, not a voltage.
And even that is 3.65v.
Daly has standard cut off voltage of 3.75v, and that is OK also.
For health charging the first 80 % of the charge takes 20% of the time.
Consequently, the last 20% takes 80% of the time...
Reaching 3.65v isn't fully charged.
Keeping it at 3.65 for longer period of time will fully charge.
Easy to test.
After you reach 3.65, and you stop the charge, wait 3-4 hours, and measure again...
If it dropped to 3.4, it wasn't fully charged.
Many threads here about charging, battery university website, and lots of other sources.
Now the million dollar question:
Does lifepo4 need to be fully charged?
Do you need it?
Lead acid likes 100%.
Lifepo4 doesn't.
85-90% is just fine.
Lead acid doesn't like discharge below 50%.
Lower discharge will reduce the life cycle.
Lifepo4 doesn't like below 10-15%, but can go to 2.0v without damage.
As there is hardly any AH between 2.0 and 2.5v most BMS use 2.5v as safety. (DALY uses 2.25v)
Do you have enough capacity to do what you want it to do?
Assuming you use your battery as power source at night, and solar during daytime.
Light colours and voltages are a really bad indicator for state of charge.
We know that during charge the voltage is higher then rest, more amperage, bigger difference between charge and rest.
We know 3.65v is full, and 2.0 is empty.
Between 3.2 and 3.4v its a rough indication, where 3.2 is probably less SOC then 3.4v.
3.4v during high charge and 3.2v during high discharge both can have the same SOC.
So even those doesn't tell much.
For capacity Knowledge, a shunt and "smart BMS" are used.
It will take several cycles to determine.
As also BMS know just that 3.65 is full, 2.0 is empty.
The shunt will count the ah that is being used, charge or discharge.
Each cell reacts a little different. With bigger difference between manufacturers.
Even the shunt will have some % wrong.
For enough $$$ you can buy the good ones
After a few months of usage the BMS together with the shunt can give a good indication of the state of charge.
3 or 4 lights is impossible to say what the state of charge is, except "most likely more towards full" and "most likely towards empty".
The light indicator uses voltage to measure, and we just saw that this is a really bad indicator.
Your seller doesn't give wrong advice.
I have my units set at 54.2v, and absorption 54.1v.
There is a difference between sensing voltage and current voltage use.
Your BMS measures the sensing voltage, the inverter what it uses.
Cables already make a difference.
With 54.2 I have about 54.8 at the cells.
My inverter doesn't measure fully accurate.
Like a garden hose pressure at the tap, and after xx meter hose..
Different pressure.
It doesn't really go one on one, water pressure and battery voltages and sensing.. gives (I hope) better understanding.
If you aren't short on battery capacity, 3 or 4 lights is just fine.
Lifepo4 doesn't need (or like) 100% charge.
Personally I would set the 2 voltages more close to eachother.
There are a lot of factors that influence the lights, for starters how many there are...
On a scale of 10, I would be worried with 3 or 4.
Scale of 5, a little bit.
Without knowing what voltage the lights have to be 3, or 4 or 5...
And even then..
Voltage, a really bad indication.
The only one we can get quickly, and it does tell something, better then nothing. Not a lot better.
