The conversion of direct current (DC) from a battery bank or a solar panel array to alternating current (AC) is essential to drive the majority of AC-powered household appliances and devices.
The conversion process is not a hundred percent efficient as some power is lost due to heat dissipation as the low voltage DC is converted to high voltage AC.
If passive heat dissipation on the inverter is insufficient, a blower fan must draw cool air over the cooling fins. Blower fans are prone to becoming noisy due to continuous running wear, dust and dirt build-up, or minor obstructions drawn in from the air inlet.
The most common type of inverter fan is a 12V DC brushless fan that keeps the inverter components and wiring cool. Keeping the inverter cool, cooling fans must be well maintained to prevent breakdown. In case of excessive noise coming from the fan, check for:
- Worn bearings or bushings on the fan motor
- Inverter load is too high
- Battery charge capacity is depleted
Let’s look at how inverters need to be kept cool to function optimally.
Why Does The Inverted Get Warm And Noisy?
Inverters are designed to convert direct current (DC) to alternating current (AC) from DC sources like battery banks on solar arrays. During the conversion process, heat is generated in the wiring and componentry that comprise the inverter.
Even the highest quality copper wire has some internal resistance to the flow of electrons through the conductor. The wire thickness also affects the ability of the conductor to allow electrons to flow. The resistance to flow causes the internal wiring and components in the inverter to build up heat.
The inverter must be installed in a well-ventilated area away from living spaces where the noise of the cooling fan may cause bother. The cooling fan needs to function correctly to prevent the inverter components from overheating and potentially failing.
Yet it is pretty standard for inverter cooling fans to become noisy and fail.
Common causes of fan failure
The fan may be noisy or shut down if the cooling fan does not receive sufficient power from the DC source, such as the battery bank or solar array. Inverter fans should not be running continuously as this signals that the system is overloaded and thus, overheating.
The cooling fan should only kick on occasionally when the inverter is operational in providing AC to one or more appliances. Ensure that there is sufficient power to run the inverter.
Assuming you have a 3000W inverter with a 2000W draw on it running on a 12V battery bank, you will require a battery with a capacity of at least 2000W/12V = 167Ah. Always add a safety factor of at least 10% and round up to the nearest hundred.
A 12V battery with 200Ah would thus be sufficient to power the 2000W draw and power the inverter cooling fan. Ensure that you have adequate power capacity in your battery bank or a solar array.
Overloading
It is also expected that inverters become noisy when they are being overloaded. When this happens, there is not enough energy to power the inverter cooling fan. Inverter capacity is always stated in Watts (W), and the sum of the power needs from appliances linked to the inverter must not exceed the Watt rating of the inverter.
Due to inverter inefficiency, you should always allow for 20% less power draw than the maximum Watt rating of the inverter. If you have a 3000W inverter, do not load it with more than 2400W power draw.
A noisy inverter cooling fan is a sure sign that the inverter is in distress due to a likely overload. Cooling fans should run quietly, cycle on and off, and not run continuously.
The remedy is to reduce the inverter’s load and ensure that you have sufficient battery charge capacity.
Temperatures
Extreme temperatures can also affect the functioning of your inverter. Inverters are designed to run within a temperature range of -13F to 140F (-25C to 60C). It is more likely that your inverter will experience high temperatures instead of extreme cold.
The efficiency of the cooling fan to provide sufficient cooling at temperatures approaching 140F deteriorates. An inverter operating outside the operational temperature range will run at a reduced output rating.
Inverters must be installed out of direct sunlight in a well-ventilated, cool, and dry location. A location near the battery bank is ideal, and batteries are also sensitive to extreme temperatures.
During cold weather conditions, the output from solar panels is higher. The cooler temperatures also assist in keeping the inverter components cool, allowing the cooling fans not to run less often.
What Is The Most Common Cause Of A Noisy Inverter?
Battery-related problems are often the cause of inverter malfunctions. The cooling fans are powered by the batteries and will thus not run if the battery is not sufficiently charged.
Common battery problems are:
- The battery does not charge
- Blown fuse
- Damaged rectifier
- Loose wiring
- Corrosion on contacts
- Reversed battery terminals
Check that the battery cable to the inverter is of sufficient thickness to cope with the current and voltage drop. Replace corroded battery terminals and connections. Check that the terminals are correctly attached according to their polarity.
Replace blown fuses and test the condition of all batteries in the battery bank for dead cells. Ensure that the charge controller charges the battery bank sufficiently before switching the inverter.
A noisy inverter fan is a sure sign of a problem. The fan may be overworked because the system is constantly overheating due to overload. Heavy loads placed on the inverter will require it to run at near maximum capacity for long periods. This will lead to overheating and the cooling fan running at high speed.
Check that the air intake and fan blades are free of dust and grime. The fan motor may also have worn-out bearings or bushings that generate a lot of noise. In this case, replacing the cooling fan with a good quality sealed ball bearing type fan with a service life of 80,000 hours is better.
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