Growatt spf 5000 es 48 V

[haissamx]

Hello,
I'm a newbie to renewable energy and solar.
I have installed a 2.7 KW 48 v system with 6 panels 450 W each, Growatt SPF 5000 es inverter, and 4 Lead-acid batteries.

Everything is running smoothly, except that the inverter is not keeping the floating voltage for batteries above 50 v.

While charging the batteries voltage is between 56 and 58 v, but automatically the inverter is discharging till 50 v.

Please check the attached two images

I tried with USE and FLD batteries types with default values but with no success.

Can someone help?

Thank you