Inverters are the sacrificial interface components in a power supply system. The inverter protects the battery bank from becoming too deeply discharged and protects them from power spikes and instability in the power grid.
Downstream from the inverter, it supplies pure sine-wave alternating current of stable voltage to AC-powered devices and appliances.
Inverters will indicate an Overload condition by illuminating a red LED, indicating that the inverter was overloaded and has tripped. If the “Reset” button does not return the inverter to operational mode and the Overload LED remains lit, the inverter has sustained some internal component damage.
Correcting the Overload Fault requires the reset procedure must be followed:
- Turn off the inverter and unplug the devices connected to it;
- Press and hold the On/Off button until the inverter emits a beep and releases it;
- In the absence of an On/Off button, unplug the inverter from the AC connection for five minutes and then plug it in again;
- The inverter should now be “On,” and the On/Off LED should be lit;
- Press the “Self-Test” button for three seconds;
- If all is well, you can plug the selected AC loads back into the inverter;
- If the Overload fault persists, then the inverter has sustained internal damage.
Inverters can sustain damage to internal components and circuits in a severe overload condition or due to a voltage surge from the AC grid power. Let’s see how we can diagnose and address this fault code.
What Can Cause An Inverter To Overload?
Inverter overloads may result from a faulty inverter, poor cable connections, damaged appliances connected to the inverter, or a voltage and current surge.
Inverters are designed to sound an alarm and indicate an Overload condition in the event of any of these four conditions, but it will require some troubleshooting to define the root cause of the error.
Inverters do not last forever; even when they are run within 80% of the maximum output power, the internal components degrade due to heat and fail over time. Typically a well-run and maintained inverter should last ten years.
The cabling connecting the inverter to the battery has to be the correct gauge and high-quality copper wire. The cable connectors must be properly crimped onto the wire ends and secured on both the battery terminals and the inverter connector block.
Frayed or loose wiring can cause overheating and lead to problems with the inverter functioning. The cables on the AC output side to the appliances are less critical and need to be secure.
Defective appliances connected to the inverter may also cause damage to the inverter that could result in an Overload error condition that will persist after the reset procedure due to damage to inverter components.
Electrical motors require an inductive power load, and hence inverters are rated for their maximum operational watt output and how much surge watt output they can produce.
If the maximum operational output or surge output is exceeded for prolonged periods, the inverted can sustain component damage.
How To Diagnose An Overload Problem On An Inverter?
If you are experienced in working with electrical power and using a multi-meter, you can attempt these procedures, but due to the significant risk of electrical shock, you should not attempt this work if you are inexperienced. Make use of a qualified technician.
- Firstly test the inverter to rule out the possibility that the inverter is the cause.
- Shut off the inverter
- Check the battery bank charge
- Is the battery sufficiently charged?
- Are the batteries well maintained?
- Are all the cable connections secure and free of corrosion?
- Clean up terminals and secure all connections
- Charge the battery bank if the SOC is low
- Disconnect all appliances and loads from the inverter
- Check that the sum of the appliance wattage requirements is less than 80% of the operational watt rating
- Turn the inverter ON. If the Overload error persists, press the Reset button and wait for the system to reset.
- If there is no Reset button, use the inverter ON/OFF button. Turn the inverter OFF for five minutes and back ON again.
- If the Overload error persists, it is most likely that the inverter has sustained damage to some components and circuitry. The inverter will have to be repaired or replaced.
- If the inverter switches back on again and there are no error codes or warning beeps, check the appliances connected to the inverter when the error appears.
Please note that an inverter rated for an operational output of 3000W should never be run at this maximum output for prolonged periods. You should balance the load at 80% of 3000W = 2400W.
Check the operational power draw and surge draw of each appliance that was previously connected. Ensure that the sum of the operational power draw of all the connected appliances should not exceed 80% of the Watt rating of the inverter.
Also, make sure that the surge power required by inductive loads such as electrical motors does not exceed the surge capacity rating of the inverter. Connect the appliances to the inverter one at a time and try to isolate the appliance that has caused the problem.
If an appliance fails to run on the inverter, connect it to a regular AC outlet and test to see if it will run. If it fails to run with grid AC, it is most likely that the appliance is defective.
What Happens If An Inverter Is Overloaded?
Inverter overload will cause older type inverters to fail and potentially cause damage to the connected appliances. Modern inverters are designed to protect the appliances and the battery bank and stop working before any damage is caused.
A noisy inverter is a sign that the inverter is struggling and may be overloaded. However, modern inverters will refuse to run if they sense an overload condition.
If the inverter is running and an additional appliance is connected, that will result in an overload. The inverter will signal an error and trip to protect the system.
The inverter will shut down automatically and indicate an Overload condition. Some inverters will turn back on automatically when the load is reduced to below the shutoff threshold.
It is worth investing in a modern inverter with sufficient capacity and extensive safety protection features that will shut off and indicate the failure mode.
Inverters typically cost only 18% of the battery bank’s cost, and it protects the investment in the batteries and the downstream AC appliances.