I am using Sunon-E 3KVA together with the battery. Simple setup. 
when the power comes from the city, it is feeding a battery (in parallel), when there is an outage, I can switch inverter to use a battery to feed consumers in my apartment (like refrigerator, router, lights).

Currently, the problem is that I have a dead zone, the inverter is configured to “see” the battery until it goes lower than 25 volt. In the case of the battery goes lower, the inverter shuts down itself and stop providing power to the consumers.

the problem is that when the city resumes giving the power, the inverter still can’t “see” the battery and left in shutdown mode.  
 

What kind of battery are you using?

If it's lithium with a BMS, the BMS could be disabling discharge because one of the cells has low voltage.

Make sure the battery cells are well balanced, in order to minimize chances of one cell going too low.

Also, does the voltage shown on the inverter match the voltage of the battery (check via a multimeter)?

Sometimes there is a discrepancy between the two, so the inverter continues to discharge, but the battery is really at a lower voltage.

 

Edited July 16, 20241 yr by meetyg

On 2024/07/14 at 8:49 AM, Kos said:

I am using Sunon-E 3KVA together with the battery. Simple setup. 
when the power comes from the city, it is feeding a battery (in parallel), when there is an outage, I can switch inverter to use a battery to feed consumers in my apartment (like refrigerator, router, lights).

Currently, the problem is that I have a dead zone, the inverter is configured to “see” the battery until it goes lower than 25 volt. In the case of the battery goes lower, the inverter shuts down itself and stop providing power to the consumers.

the problem is that when the city resumes giving the power, the inverter still can’t “see” the battery and left in shutdown mode.  
 

May be as @meetyg indicated but after a shutdown which is a serious condition my 3kW inverter would not come on until I switch it off and on again via the switch. 

This I see as condition one must acknowledge before operation again.