During charge the voltage is higher then "real" voltage.
Depending on how fast you charge..
C 0.5 is possible, 140A on 280Ah cell.
Your reading is not the rest voltage.
It's within specifications to go up to 4.2v without real damage.
Charging is supposed to stop at 3.65 to prevent damage.
Even at 3.65, stop charging the cell will go to rest mode and after time it's about 3.375 - 3.450v (0.5% SOC difference)
At 3.4 a cell that haven't been used a few days you can consider it fully charged.
It's a funny thing, charging battery.
It's chemical imbalance gives fluctuations that aren't visable.
If you fill a glass of water quickly with a bucket, you might get all the water inside at start.
The higher the water level, more challenging it is not to spill anything and still go fast.
Water is in movement and full (level where you start spilling) isn't really full.
Do the same with a slow flow of water and when it spills the glass is full. Absolutely top.
Can you say that when you spill the glass is full??
This is about the best visual I can think of to let people understand how high and low current Influence what you think as full.
Once in rest (water takes just a few seconds) you see the real level.
Lead acid takes 6-12 hours.
LiFePO4 a few. (3-4)
4.1 isn't always bad. If you are charging at high current it's "normal"
If you are charging at low current and just pass the 3.65 safety level to see if you can charge more then 100%....
Then it is bad, really bad.
In getting bloated cells bad.
Bloating is delaminating sheets.
Sheets who have too much space between them no longer are active part of the battery and as result reduce the capacity of the cell.
I really can advise anyone to try manually charge a LiFePO4 cell, and monitor it closely.
Untill you experienced the waiting for hours at 3.49 and the short time it takes to shoot up from 3.5 to 3.65 and higher it's hard to understand how even at constant voltage, BMS is essential to stop.
And dump load is essential to be able to keep the cells in balance.
It's like filling that glass of water where you think, or think you see it's only 3/4 full and suddenly it overflows..
Like WTF??
That can't be right it still should be able to keep more water!
Kinda bizarre
Or just accept that it works this way and accept that chemistry is strange.
Daly 35mA have kind of low dump load, but usually sufficient.
Average is 200mA and enough to slow down the boost from 3.5 to 3.65 so the other cells can catch up
.
DIYBMS have 850mA, and is intended for "used frankenpack"
All your old mismatched crap giving a second life and fix the imbalance with the old/new and capacity mismatch.
A new setup with matching brand /capacity /age a Daly 35mA is strong enough to keep the balance.
Hopefully giving indication how little imbalance there will occur with a good setup.
Something that an active balancer can fix before there is a need to top balance, avoiding all the potential risks of top Balance.
It's just not nice if you are depending on the cells for your energy supply and you need to to top balance...
Chances are the BMS will stop at 3.65, and if you use common bus (charge and discharge via the same hybrid unit) the BMS will also stop the discharge...
No discharge no electricity for your home.
I use the DIYBMS as it uses contactors, and I simply disconnect the solar panels (DC, +300v, +/-10A)
3 x hybrid = 3 contactors, one relay
Chargery can work the same way.
Daly? ( And most others)
It just stops all power from and to the battery array.
Leaving you in the dark for half an hour (or longer) waiting for the highest cell to do its natural voltage reduction as it's in rest.
And then the cycle starts again.
Few minutes charging, trying to slow the highest cells, with 35mA not a lot of slowing down power..
Go dark..
Wait..
Charge
Eventually the sun is setting, giving less solar power to the MPPT, less charge to the cells, no charge to 3.65
And the next day the dance starts again.
In a few days the battery array is fully top balanced.
Or you top charge always.
As it's the intended way of usage for BMS like Daly.
Top charge isn't bad.
You get +/- 2000 cycles as advertised and not +/- 3500.
If you want to get maximal cycles, you will charge to 85-90% and have significant imbalance between the cells, and that's OK as it's not a probleem.
Just don't expect your Daly to be able to cope with 5,10 or even 20% imbalance in one day of top balancing....
It was expecting (and build for) 0.5% max....
Active balancer...
That can keep the imbalance of the array at lower%, depending on your build and cells even prevent the need to top or bottom Balance at all.
(And still use max. 85-90% top charge)
I totally agree with all people who say that active balancer is useless product, totally unnecessary and waist of money.
If you always charge your LiFePO4 cells to +95%. Yes. Do not buy.
You would spending your money on something that have totally no additional value and only costs some energy from your array.
If you don't want +95%...
You will increase the imbalance that natural occur, not make it faster, just not adjust every day.
That come with a price and a perk.
Perk 1000 cycles extra.
Price larger % imbalance.
What an active Balancer or BMS with enough dump load capacity can fix
