With this Python module you can read modbus registers and xml api values from various VARTA batteries. Tested on my VARTA element/12 battery. Should work for other VARTA element, pulse, pulse neo, link and flex storage devices as well.
pip3 install vartastorage
from vartastorage.vartastorage import VartaStorage
#ip and port for modbus host
varta = VartaStorage('10.0.2.3',502,'pass123456')
from vartastorage.vartastorage import VartaStorage
#ip and port for modbus host
varta = VartaStorage('10.0.2.3',502)
#update all values provided by modbus server
varta.get_all_data()
#show current grid power
print(varta.grid_power)
#update only state of charge
varta.get_soc()
#show battery SoC
print(varta.soc)