If public electricity is available but your inverter battery percentage is not increasing, there is likely a problem somewhere between the incoming power, inverter charger, battery, or system settings.
Before assuming the battery is bad, work through the following checks.
1. Confirm that grid power is actually reaching the inverter
Your house may have electricity while the inverter input circuit does not. A dedicated breaker, socket, cable, or changeover arrangement may be disconnected or tripped.
Check the inverter screen for an AC input or grid symbol. If the unit does not detect incoming power, the charging problem may be on the input side.
2. Charging may be disabled in the settings
Hybrid and programmable inverters often allow users to choose when batteries should charge and which source should be used. A setting can accidentally be changed to solar-only charging, limited grid charging, or a charging schedule.
Review the charging settings using the official manual for your exact model.
3. The battery may already be near full charge
Some systems reduce charging current significantly when the battery approaches full capacity. The percentage can appear to move slowly or remain unchanged for a while.
If the battery is already above 90%, this may be normal depending on the battery type and charging algorithm.
4. The battery may be too deeply discharged
A severely discharged battery can sometimes trigger protection that prevents normal charging. Lithium batteries may also enter a protection state controlled by the battery management system.
If the battery voltage is unusually low, do not attempt improvised charging methods. A technician should determine whether the battery can be recovered safely.
5. A battery cable or terminal may be loose
Loose or corroded connections increase resistance and can prevent normal charging. They may also become dangerously hot.
Do not touch battery terminals while the system is active. If you notice corrosion, heat damage, or loose cables, shut the system down correctly and have the connections inspected.
6. The charging current may be set too low
Some inverters allow the maximum grid charging current to be adjusted. If this is set very low, a large battery bank can take a long time to charge.
Do not simply increase the setting to the highest value. The correct current depends on the battery chemistry, capacity, manufacturer guidance, cable size, and inverter specification.
7. The battery may be aging
An old battery can accept charge slowly or show misleading state-of-charge readings. It may charge to a displayed 100% and then drop rapidly under load.
A proper capacity test can reveal whether the battery still stores useful energy.
8. The inverter charger may have developed a fault
If grid input is present, the settings are correct, and the battery connections are healthy, the inverter’s charging section may need service.
Possible signs include no charging current, recurring charger error codes, overheating, or the unit charging only intermittently.
What you can safely check
- Whether the inverter detects grid input
- Whether the battery percentage changes over several hours
- Whether a charging symbol appears
- Whether a fault code is displayed
- Whether charging settings have been changed
- Whether the system recently experienced an overload or surge
When professional help is needed
Call a qualified technician if the battery is swollen, leaking, unusually hot, giving off a strong smell, or if any cable insulation is melted. Stop using the system if you see smoke or sparking.
Final thought
A battery that refuses to charge does not automatically need replacement. First confirm that grid power is reaching the inverter, charging is enabled, and there is no fault code. If the simple checks do not solve the problem, testing the charger and battery separately is the safest next step.