Float charging uses a lot of power

[carlabudar]

Hi,

My brand new system consists of:
- SMA HomeManager2.0
- SMA SunnyIsland8.0H-13 (SI) - battery inverter
- SMA SunnyBoy3.0 - solar inverter
- Solar collectors mono-crystal 9*370W = 3330W (9*2m2 = 18m2)
- Batteries lead-carbon 8x200Ah, 4 in series, two series in parallel, in the end i have 48V,400Ah
- Battery equalizer for each series (2x https://zhcsolar.com/product/battery-equalizer-for-lead-acid-batteries/)



After initial connection of batteries to SI, it needed more than 24h to charge batteries up to 100%
Batteries are bought 6 months before i connected them to SI. For that time they were placed in dry basement at 15-20 degrees Celsius.
After batteries have charged up and inverter was showing 100%, inverter went to "float charge" mode = keeping battery charged

First day in that regime, inverter keep charging battery with power of 120W, after 2 days in float charge that charging power slowly fell to 40W.
I tried to switch on/off battery balancer but without any change in power of charging from SI.
My question: is it normal that power of float charge is so high only to keep batteries charged to 100%?
Is there maybe a problem in too high voltage values in battery configuration so battery is actually overcharging?

At the first day of charging actually i have entered wrong voltage values after i realized that i can hear barely audible sounds of bubbling. After i did some fast research i realized that this sound is something that must never be present with this kind of batteries. After that i realized that data that i got from seller were wrong. I found the right data on manufacturer website, voltages had to be lower. After adjustment , bubbling stopped.
I also have to notice that i still can fill a smell of the batteries if i bring my nose close to them. Barely noticeable but still i can sense it.
Does anyone have any advice or experience regarding battery smell? Is it normal?
What do you say about that constant current that SI is giving to the battery aldough it is at 100%?
Do you think i should try to run equalize charge?


Thank you all in advance!

 

[brum]

What is the float voltage? Can you measure it on each cell to see if they are at the same voltage during float charging?

But in general - a 400A battery should have ~400mA trickle charge. Do the math (48V * 0.4A) and you are at ~20W. Pretty close to the 40W you see. Considering some minor imbalance between the batteries and 40W seems reasonable.

 

[carlabudar]

Hi, thank you for your reply!

Float charge voltage is set to 2.27V per cell or 13.62 per battery or 54.48V for whole series.
However goal voltage is set by SunnyIsland to 54.83V (13.7075 per battery) (probably because of temperature compensation)
When i measure each battery individual i have voltages between 13.64 and 13.7V (i don't have precise voltmeter, so it enters some error also)
these values are when Battery Balancer is operating. I think maximum differences increases for about 0.03V when i turn off battery balancer.
Do you think those values are expected?

Do you think i need to run equalize charging?

 

[brum]

The deviation between batteries is OK. I don't think there is an imbalance between them.

Check your battery specs to see if these voltages are expected (and correct) and if equalization charging is needed.