4s charging profile check

[foto40]

Hi guys,
I've checked many threads and my mind is full of nonsense now.
I have a pack of four 280ah Eve lifepo4 with 250A daly (unfortunately) bms.
These are the setting:
Cell volt high protect 3,45 (off-grid garage reccomendation)
cell volt low protect 2,95
sum volt high protect 13,60
sum volt low protect 11,8

I have an epever 40A also and these are the main settings:
Absorbing 14,2 (should be 4x3,45=13,6?)
Float 13,4

The question is should the parameters on epever be equal to the parameters on daly bms or should be a little higher to charge the pack more efficiently?

 

[John Frum]

Hi guys,
I've checked many threads and my mind is full of nonsense now.
I have a pack of four 280ah Eve lifepo4 with 250A daly (unfortunately) bms.

I think you are confusing BMS settings with charge profile settings.

These are the setting:
Cell volt high protect 3,45 (off-grid garage reccomendation)

this should be 3.65 volts

cell volt low protect 2,95

this should be 2.5 volts

sum volt high protect 13,60

this should be 14.6 volts

sum volt low protect 11,8

This should be 10.0 volts

I have an epever 40A also and these are the main settings:
Absorbing 14,2 (should be 4x3,45=13,6?)

14.2 is fine

Float 13,4

13.4 is fine.

The question is should the parameters on epever be equal to the parameters on daly bms or should be a little higher to charge the pack more efficiently?

No the charge profile should be safely inside the bms parameters.

 

[foto40]

I think you are confusing BMS settings with charge profile settings.

Well, that's right. I can't resolve this misunderstanding in my mind. So you say that I should not change BMS factory settings and set the one which you posted. Lets assume that I want to charge my pack to 13,8V(4x3,45V), as I found somewhere that victron suggests this setting, I should limit only absorbing to 13,8V?

 

[John Frum]

I can't resolve this misunderstanding in my mind.

Why not?

So you say that I should not change BMS factory settings and set the one which you posted.

Depends on the bms factory settings.
Daly sometimes have very strange default settings.

Lets assume that I want to charge my pack to 13,8V(4x3,45V), as I found somewhere that victron suggests this setting, I should limit only absorbing to 13,8V?

Did you read the doco I linked in my first post?
I don't recommend terminating charge at 13.8VDC unless your battery is tripping on cell over-voltage at higher charge voltages.

 

[foto40]

Why not?

Because I can't find answer to the question whether should I end charging when the BMS stops it ( cell high voltage or sum high voltage) or adjust charging with MPPT? Should I treat bms settings as the last resort ?

Did you read the doco I linked in my first post?
I don't recommend terminating charge at 13.8VDC unless your battery is tripping on cell over-voltage at higher charge voltages.

Ye sure I've read it. According to this quote I decided to terminate charging at 13.8V(4x3.45V) "Exposing an LFP battery to charge voltage above its full resting voltage of aproximately 3.45 volts per cell causes unnecessary stress."

 

[John Frum]

Because I can't find answer to the question whether should I end charging when the BMS stops it ( cell high voltage or sum high voltage) or adjust charging with MPPT?

The BMS should not be used for charge termination.

Should I treat bms settings as the last resort ?

The BMS should never have to disconnect the battery in a properly coordinated system
Its like the reserve parachute.
For example: Lets say your MPPT charge controller malfunctioned, the BMS can disconnect the charge path to protect the battery.

Ye sure I've read it. According to this quote I decided to terminate charging at 13.8V(4x3.45V) "Exposing an LFP battery to charge voltage above its full resting voltage of aproximately 3.45 volts per cell causes unnecessary stress."

I guess I will have to update that doco.
Its harder to maintain a proper top balance when you only charge to 3.45V per.
I suggest 3.55v per if your BMS doesn't trip.
I consider charging into the high knee to be a necessary stressor.
Excessive absorption in the high knee is an unnecessary stressor.
Floating in the high knee is also an unnecessary stressor.

 

[BC-Steve]

I have a similar setup with 304ah. See this post https://diysolarforum.com/threads/e...ever-solar-cc-and-daly-bms.38352/#post-488660