Advice on strange behavior active balancer daly

Good morning forum, I would like to have your opinion on the behavior of the active balancer that I purchased last week. Let me start by saying that I assembled a 16S pack for home energy storage application, with eve fl105 cells. Daly brand BMS for home battery applications, and a 5A 16S active balancer also added by Daly. I assembled 2 of these battery packs and placed them in parallel with a positive and a negative bush bar. At this point I notice that one of the two packs is behaving anomalously, unlike the other, in the sense that I notice excessive draining. In particular, if in the package that works well, let's assume the charger is disconnected at 57.5V, with the balancing I arrive at a final voltage of 57V, and let's say that I am satisfied. In the other pack however, as soon as it switches off at 57.5V, balancing begins and after an hour the voltage drops to 54V or even lower. The cells are from the same batch purchased from Nkon, grade A, with a discharge cycle done by me (purchased new). I'll give you some more information:
- Charge cut-off: highest cell at 3.632V, lowest cell at 3.478V
- After 50 min: highest cell 3.397V, lowest cell 3.363V
-After an hour and a half: highest cell 3.369V, lowest 3.348V
Do you consider the behavior normal?
Can it be blamed on the balancer?
I would like to avoid exchanging the two balancers with each other because they are very delicate and would require breaking them both.
Thank you for the support

is that delta the same each time you charge? while currently folks are saying no need to top balance with an active balancer i say horse hockey. why not top balance? It simply makes the job of the active balancer easier to begin with.

Sorry i don't understand your reply, did you want to advise me to delve deeper into the reason why the balancer didn't balance well, or to be satisfied with the result? In any case I would like to say that the balancing result is always constant over time but significantly lower than the other battery pack. In my opinion I lose 500-600 Wh, which is not a lot.

Looks like your cells are out of balance, and the active balancer is bleeding off the high cell, not transferring to the low. Hmmm.

I’d either manually top balance the cells, or keep charging after the voltage settles until the gap is closed.

Supervstech said:

Looks like your cells are out of balance, and the active balancer is bleeding off the high cell, not transferring to the low. Hmmm.

I’d either manually top balance the cells, or keep charging after the voltage settles until the gap is closed.

Click to expand...

is that delta the same each time you charge? while currently folks are saying no need to top balance with an active balancer i say horse hockey. why not top balance? It simply makes the job of the active balancer easier to begin with.

Daddy Tanuki said:

is that delta the same each time you charge? while currently folks are saying no need to top balance with an active balancer i say horse hockey. why not top balance? It simply makes the job of the active balancer easier to begin with.

Click to expand...

Why not? It's a lot of work is why.

You need a better balancer. I'm running the 15a neey currently, it's not ideal but it works. You need to be able to set it to only balance near the top, say above 3.37 or 3.4 average.

You have problems when
A) balancer operates at lower voltages and unbalances
B) amperage too low so it can't actually do it quickly

You can get by with lower amperage if you idle at 3.4 a lot, but I recommend the overkill that 15a is. It's been very nice.

Also stop checking your cells so much. What you really want to check is how many ah you get from top to bottom. If that number degrades you have a problem, otherwise your problem is solved by not checking anymore.

Tailele said:

il delta è lo stesso ogni volta che carichi? mentre attualmente la gente dice che non è necessario bilanciare il massimo con un bilanciatore attivo, dico hockey a cavallo. perché non il massimo equilibrio? Rende semplicemente più semplice iniziare il lavoro del bilanciatore attivo.

Click to expand...

Scusate il ritardo e quindi le batterie erano già scariche.

zorlig said:

Hai bisogno di un bilanciatore migliore. Attualmente sto eseguendo il 15a neey, non è l'ideale ma funziona. Devi essere in grado di impostarlo sul bilanciamento solo vicino al massimo, diciamo sopra la media di 3,37 o 3,4.

Hai problemi quando
A) il bilanciatore opera a tensioni e squilibri inferiori
B) amperaggio troppo basso quindi non può farlo velocemente

Puoi cavartela con un amperaggio inferiore se giri molto al minimo a 3,4, ma ti consiglio l'eccessivo 15a. È stato molto bello.

Inoltre smettila di controllare così tanto le tue cellule. Quello che vuoi veramente controllare è quanti ah ottieni dall'alto verso il basso. Se quel numero peggiora hai un problema, altrimenti il tuo problema si risolve non controllando più.

Click to expand...

you're probably right, it would be better not to look, but I installed the system a week ago and I wanted to check that everything was set correctly. I would add that the functioning of two similar systems seems strange to me. Secondly, I don't want to lose too much energy while balancing.

Tailele said:

Scusate il ritardo e quindi le batterie erano già scariche.

you're probably right, it would be better not to look, but I installed the system a week ago and I wanted to check that everything was set correctly. I would add that the functioning of two similar systems seems strange to me. Secondly, I don't want to lose too much energy while balancing.

Click to expand...

Voltages on lifepo4 have little meaning and the cells we buy are factory rejects that have different voltage curves, especially at the top.

To know for sure you need to set the charger to hold voltage for every cell at 3.4, then watch it during a discharge and charge cycle. That will tell you what voltage differences for your specific cells are expected when perfectly balanced.

What you want want to do is measure AH from top to bottom though a cycle and make sure you are getting say 95% of your stated capacity. Then test it again in say 1, 6, 12 months and compare. If it degrades a lot get a better balancer. Otherwise you are good to go.

zorlig said:

Why not? It's a lot of work is why.

Click to expand...

And messing around after the fact doesn’t waste time? I have eight 12 volt batteries with cells all from the same batch, six of theses packs I took the time to top balance and two I didn’t. The first six stay balanced, the other two have to balance every charge. Only thing different was doing an initial parallel top balance.

Tailele said:

Sorry i don't understand your reply, did you want to advise me to delve deeper into the reason why the balancer didn't balance well, or to be satisfied with the result? In any case I would like to say that the balancing result is always constant over time but significantly lower than the other battery pack. In my opinion I lose 500-600 Wh, which is not a lot.

Click to expand...

do you have that same loss everytime? or was it a one time thing?

Tailele said:

I'll give you some more information:
- Charge cut-off: highest cell at 3.632V, lowest cell at 3.478V
- After 50 min: highest cell 3.397V, lowest cell 3.363V
-After an hour and a half: highest cell 3.369V, lowest 3.348V
Do you consider the behavior normal?
Can it be blamed on the balancer?

Click to expand...

Yes normal assuming the battery is fresh. Takes some time to balance. Depending on use could be 3 to 6 months.

I purchased 8 12v 100ah batteries, the bms would disconnect before hitting 13.8v you could not charge it up to 14.4 not even once.
This was because one cell was higher than the others, and would hit bms disconnect first.
Well i figured if i set the scc to 13.8, eventually it would balance out, and id be up to balanced capacity...

Nope.
After a year the batteries failed.
I took them apart and found several dead, zero volt cells that will not take a charge.

Dont delay, top balance your packs.

I have SEVERAL 100Ah cells that are garbage...

Supervstech said:

I purchased 8 12v 100ah batteries, the bms would disconnect before hitting 13.8v you could not charge it up to 14.4 not even once.
This was because one cell was higher than the others, and would hit bms disconnect first.
Well i figured if i set the scc to 13.8, eventually it would balance out, and id be up to balanced capacity...

Nope.
After a year the batteries failed.
I took them apart and found several dead, zero volt cells that will not take a charge.

Dont delay, top balance your packs.

I have SEVERAL 100Ah cells that are garbage...

Click to expand...

I would first suspect they were marginal cells from the start. Especially if they never balanced out with an active balancer.
Just water under the bridge now.

Supervstech said:

I purchased 8 12v 100ah batteries, the bms would disconnect before hitting 13.8v you could not charge it up to 14.4 not even once.
This was because one cell was higher than the others, and would hit bms disconnect first.
Well i figured if i set the scc to 13.8, eventually it would balance out, and id be up to balanced capacity...

Nope.
After a year the batteries failed.
I took them apart and found several dead, zero volt cells that will not take a charge.

Dont delay, top balance your packs.

I have SEVERAL 100Ah cells that are garbage...

Click to expand...

Consider that I received the cells last week, they are grade A, and they were unbalanced between one and the other by 0.002V, all were specified at 3.25V. What I can do is with the Bmax charge them all to the maximum (one at a time), it will take a long time because they are 105 Ah. So I detach all the bushbars and I can try to load them like this. Honestly, I don't expect improvements, because when I get home around 1 PM, I find them all balanced at 3.35 V with a maximum deviation of 0.008V. Personally, I'm not a battery expert, but if the functioning of an active balancer (paid 70 euros) is to transfer energy from the most charged cells to the most discharged ones, I don't understand how the most discharged cell loses 0.1V during this process. I can understand that perhaps a cell performs better and charges better, so it reaches the 3.65V or 3.63V threshold sooner (how I set the BMS). For completeness I attach these photos, I will try to provide more today. Thank you very much for the support

I m here. I take a picture of the balancing. As you could see , I have a good balance but with a low voltage. I started the charging phase but at the end I found a difference higher than 0.14V and then another drain to reset the voltage to a normal state.

Yes the voltages will diverge at the top of charge and converge in the middle capacity.
Those numbers look reasonable for a newish build. Trouble is the balancer does not do anything until the voltages diverge at the top. So maybe 10 to 30 minutes of actual balancing per day and will improve over then next couple months.

As long as there is no cell over-volt shutdown all is fine.

time2roll said:

Yes the voltages will diverge at the top of charge and converge in the middle capacity.
Those numbers look reasonable for a newish build. Trouble is the balancer does not do anything until the voltages diverge at the top. So maybe 10 to 30 minutes of actual balancing per day and will improve over then next couple months.

As long as there is no cell over-volt shutdown all is fine.

Click to expand...

this morning I tried to reduce the charging voltage, bringing it from 57.5V to 55.8V, in order to keep the cell voltage lower and not let one of the cells reach 3.63V (as the upper charging limit). In this way from around 97% up to 100% I have a much slower filling, where I suspect the balancer can work better. I will do some tests, perhaps slowly setting the voltage to 56V.

Get a Victron Battery Balancer - problems over.

Victron Battery Balancer​

The Battery Balancer equalizes the state of charge of two series connected 12V batteries, or of several parallel strings of series connected batteries.
When the charge voltage of a 24V battery system increases to more than 27V, the Battery Balancer will turn on and compare the voltage over the two series connected batteries.
The Battery Balancer will draw a current of up to 1A from the battery (or parallel connected batteries) with the highest voltage.
The resulting charge current differential will ensure that all batteries will converge to the same state of charge.
If needed, several balancers can be paralleled.
A 48V battery bank can be balanced with three Battery Balancers.

The problem:
The service life of an expensive battery bank can be substantially shortened due to state of charge unbalance One battery with a slightly higher internal leakage current in a 24V or 48V bank of several series/parallel connected batteries will cause undercharge of that battery and parallel connected batteries, and overcharge of the series connected batteries. Moreover, when new cells or batteries are connected in series, they should all have the same initial state of charge. Small differences will be ironed out during absorption or equalize charging, but large differences will result in damage due to excessive gassing (caused by overcharging) of the batteries with the higher initial state of charge and sulphation (caused by undercharging) of the batteries with the lower initial state of charge.
The Solution: Battery Balancing
The Battery Balancer equalizes the state of charge of two series connected 12V batteries, or of several parallel strings of series connected batteries.
When the charge voltage of a 24V battery system increases to more than 27,3V, the Battery Balancer will turn on and compare the voltage over the two series connected batteries. The Battery Balancer will draw a current of up to 0,7A from the battery (or parallel connected batteries) with the highest voltage. The resulting charge current differential will ensure that all batteries will converge to the same state of charge.
If needed, several balancers can be paralleled. A 48V battery bank can be balanced with three Battery Balancers.
FEATURES
LED indicators:
Green: on (battery voltage > 27,3V)
Orange: lower battery leg active (deviation > 0,1V)
Orange: upper battery leg active (deviation > 0,1V)
Red: alarm (deviation > 0,2V). Remains on until the deviation has reduced to less than 0,14V, or until system voltage drops to less than 26,6V.
Alarm relay Normally open. The alarm relay closes when the red LED switches on and opens when the red LED switches off.
Alarm reset Two terminals are available to connect a push button. Interconnecting the two terminals resets the relay. The reset condition will remain active until the alarm is over. Thereafter the relay will close again when a new alarm occurs.
Even more insight and control with the midpoint monitoring function of the BMV-702 Battery Monitor The BMV-702 measures the midpoint of a string of cells or batteries. It displays the deviation from the ideal midpoint in volts or percent. Separate deviation percentages can be set to trigger a visual/audible alarm and to close a potential free relay contact for remote alarm purposes.
Please see the manual of the BMV-702 for more information about battery balancing. Learn more about batteries and battery charging To learn more about batteries and charging batteries, please refer to our book ‘Energy Unlimited’ (available free of charge from Victron Energy and downloadable from www.victronenergy.com).
TECHNICAL DATA SUMMARY
Please Download SPECIFICATION DATA SHEET by clicking BUTTON below)
Victron Battery Balancer Input voltage range: Up to 18V per battery, 36V total Turn on level 27,3V +/- 1% Turn off level 26,6V +/- 1%
Current draw when off: 0,7 mA
Midpoint deviation to start balancing: 50 mV
Maximum balancing current: 0,7A (when deviation > 100 mV)
Alarm trigger level: 200 mV
Alarm reset level: 140 mV
Alarm relay: 60V / 1A normally open
Alarm relay reset: Two terminals to connect a push button
Over temperature protection: yes
Operating temperature -30 to +50°C
Humidity (non-condensing) 95%
ENCLOSURE Colour Blue (RAL 5012)
Connection terminals Screw terminals 6 mm² / AWG10
Protection category IP22
Weight 0,4 kg
Dimensions (h x w x d) 100 x 113 x 47 mm
STANDARDS Safety EN 60950, CSA/UL 62368-1 Emission EN 61000-6-3, EN 55014-1 Immunity EN 61000-6-2, EN 61000-6-1, EN 55014-2 Automotive Directive EN 50498

Hope this info helps