An inverter not working leaves you asking which part has failed: the inverter box, the battery, the switches or the house wiring. Most home setups, with one box and one or two batteries, fail in a fairly small number of ways, and several of them can be checked from the outside in minutes.
This page walks through those outside checks in the order a service technician would use them, explains what the lights and beeps usually mean, and draws a firm line where the work becomes unsafe for a home owner. Battery and mains wiring are on the technician side of that line.
Common causes
1Inverter switch or MCB is off
How to tellDisplay dark, no lights, nothing happens at all
What fixes itSwitch on the inverter's own MCB and the main switch
2Overload from too many appliances
How to tellBeeps, overload light, shuts off when a heavy device starts
What fixes itSwitch off heavy loads such as a pump, heater or AC
3Battery too weak or too old
How to tellBackup lasts minutes, or the inverter dies right after a cut
What fixes itTechnician tests the battery and its charge
4Battery not charging on mains
How to tellMains light on, but backup time keeps shrinking
What fixes itTechnician checks the charger section and the battery
5Loose terminal or damaged cable
How to tellDisplay flickers, burnt smell, warm lead
What fixes itSwitch off and call a technician; do not touch
6Mains input missing or tripped breaker
How to tellInverter works on backup but not on mains
What fixes itCheck the input MCB and the wall supply
7Faulty board or cooling fan
How to tellFan silent, overheat alarm, code on the display
What fixes itAuthorised technician only
How to fix it, step by step
Check the switches and the MCB
Look at the inverter's on and off switch and the breaker that feeds it. After a surge or a big cut, a breaker may have dropped. Switch on and wait a minute for the display.
See whether it is a mains or a backup problem
If the lights work on mains but go out as soon as power is cut, the problem is on the backup side, usually the battery. If it fails even on mains, think of the input supply or the inverter itself.
Reduce the load
Switch off heavy loads such as an AC, a geyser, an iron or a water pump, and start with lights and fans. If the inverter now runs, you had an overload. Add loads one at a time to see the limit.
Read the lights and beeps
Most inverters show a mains light, a battery level and a fault light, with different beeps for low battery, overload and fault. Check the manual for the pattern on your model, since beeps differ between makers.
Give the battery time on mains
After a long cut, a deeply drained battery may need many hours on mains before it can run the house again. Keep the inverter on mains and leave loads light for the night.
Check the vents and the surroundings
Keep the inverter and battery in an airy place, away from damp, direct sun and cloth covers. A blocked vent or a hot room can cause overheat shutdowns.
Call a technician for the rest
Battery tests, terminal checks, charger checks and board repairs are for a trained person. Do not open the inverter or battery yourself.
Inverter not working after power cut: the usual reasons
The cut is the moment of truth for an inverter. If it was fine on mains and dies at the first cut, the battery is the suspect, since the inverter box only turns battery power into household supply. If it also fails to switch from mains to battery, the changeover part may be at fault. If everything seems fine but a few sockets stay dead, the house wiring may be split into inverter and non inverter circuits, so test a socket that is meant to be on backup.
The power goes off, the lights flicker and then stay out. The inverter shows a low battery light and beeps. You find the battery is three years old and gave only ten minutes of backup last month. That points to the battery, and a technician can test it before you spend money on a new inverter.
Inverter not working on mains or in winter
If you ask why my inverter is not working on mains, check the wall supply with another device and the input breaker first. Then see whether the inverter's mains light is on. If the light is off, the box is not seeing supply, and an electrician should look at the input. In winter, battery capacity drops in the cold, so backup times shrink, and a battery that was borderline in summer may fail. Keep it in a sheltered spot and ask for a capacity test.
On and off switch or a bulb that does not light
An inverter on off switch not working usually means a worn switch or a board related problem, and the inverter bulb or lamp that does not light after a power cut is often only an indicator. If lights, display and fans are all dead, treat it as a power or battery issue. Do not bridge the switch with a wire, since that bypasses the protection and is unsafe.
Never open the inverter or the battery, never touch battery terminals with tools, never link wires to bypass a switch or fuse and never do mains wiring yourself. Batteries carry current that can burn and cause fires, and unauthorised work can end the warranty.
Testing your inverter: how to tell if it works, and next steps if it fails
With the house on mains, switch off the inverter's input breaker for a few seconds, as if there were a cut. If lights and fans stay on, the inverter has taken over. Switch the breaker back on. If everything goes dark, the backup side is not working, and the next step is to ask a technician to test the battery and the box. Do this test only with light loads connected, and do not repeat it many times.
Codes and display messages
| Message or sign | Usual area | What you can do |
|---|---|---|
| Overload | Too much connected load | Switch off heavy items |
| Low battery | Battery drained or weak | Keep on mains to charge |
| Overheat | Blocked vents or hot room | Improve airflow, wait |
| Fault or other code | Model specific | Read the manual, call service |
A solar or home inverter error code list, or any maker's list found online (including any UTL inverter error code list), is a hint at best. Use the one in your own manual.
Repair or replace: what changes the cost
A switch or a fuse is a smaller job. A battery replacement is the largest regular cost, and its price depends on capacity and type. A board or transformer repair sits in between. Ask the technician to test the battery first, since a tired battery is the commonest reason for a poor backup and can look like an inverter failure. For other home appliances see fridge not working and ceiling fan not working, and for cooling units, the AC error codes hub.
Frequently asked questions
Why is my inverter not working after a power cut?
The most common reason is a weak or old battery. Other causes are an overload at changeover, a switch or MCB that is off, or a loose connection. Check the switches and load, then ask a technician to test the battery.
How do I check if my inverter is working or not?
Look for the mains light and the display. Cut the mains at the breaker briefly and see whether the lights stay on. If the inverter takes over, it works. If not, the battery or the box needs checking.
What should I do if the inverter is not working on mains?
Check the input breaker and the wall socket, see whether the mains light is on and reduce the load. If the light stays off, an electrician should check the input supply.
Why does my inverter not work in winter?
Cold weather lowers a battery's capacity, so backup time falls. An already weak battery may fail altogether. Keep it sheltered and get its capacity tested.
Can I repair the inverter on off switch myself?
No. Opening the box or bypassing the switch is unsafe and can void the warranty. A technician should replace the switch or check the board.
Can an inverter run an AC or a fridge?
It depends on its rated capacity and battery. An AC is a heavy load and can overload a small inverter, while a fridge is lighter. Check the rating in the manual.