Updated: Oct 3
A home inverter is one of the most essential devices of daily life, where power cuts can be troublemaking. And living with power for a while could make us feel unsafe and uncomfortable.
Being an electrical engineer, lots of my knows ask me questions about their home inverter and I always like to clear their doubt.
Here I am going to answer some of the questions about home inverters, that is
Can the inverter be switched off when not in use?
Yes, you can switch off your inverter when the batteries are fully charged and it is not in use. But it is not advisable if you are not leaving home for 1 or 2 months. Because this will make you start the inverter manually during power cuts and reduce your battery backup time [due to self-discharge of battrey] if the inverter is switched off for a long time.
Once the batteries are fully charged they consume power less than 1% of their capacity. Hence keeping the inverter ON won’t make any difference in your electricity bills. On the other hand, if you are leaving your home for 1 to 2 months you can switch off your inverter.
Do you wanna know more about self-discharge process in home inverter battereis? Read our Epic Blog on "Why home inverter battereis get Self-discharge".
When should you turn off your inverter?
The self-discharge rate of a Lead-acid battery is 4 to 6% per month when the inverter is switched off. The power consumption of a battery during float charging is 1% of its capacity. So, if you are leaving home for a vacation of 2-3 months. It will be a little bit profitable for you to leave your inverter switched off. It won’t hurt your batteries but it will discharge your batteries by 12-18%.
Before leaving for vacation and switching off your inverter, make sure that your batteries are fully charged and their water level is full. When you come back don’t forget to switch on your inverter.
It is important to not leave your inverter switched off for more than 4 months for not so old batteries and 3 months for old batteries otherwise your batteries will get permanent damage due to high depth of discharge.
Related Post: Can a home inverter used as UPS for computer
Now here is a briefing on my answer
1. Switching off the inverter won’t make it switch on automatically during power cuts and this will lead you to stay without power during power cuts as long as you or someone else switch on the inverter. This makes completely no sense because the purpose of hanging the inverter is to save you from sudden blackouts.
2. Float charging of batteries: Batteries lose capacity when not in use, this phenomenon is called self-discharge. Hence a voltage of 13.25 volt is continuously applied to the battery terminals after the battery is fully charged. This is also called float charging of batteries.
Keeping the inverter switched off for a long period (like 2-3 weeks) will reduce the backup time of batteries. If the battery voltage falls to 10.8V, the battery should be given a freshening charge at 13.8 V for 12 hours.
3. Power combustion of batteries during float charging is less than 1% of the battery capacity. Hence it won’t make a difference in the power consumption of your home if you keep your inverter on, even if the batteries are fully charged.
The above graph shows the change in battery charging current as well as voltage during different stages of battery charging. As you can see from the above graph when the battery is fully charged it consumes a negligible amount of current once fully charged [marked by a red circle].
4. The below graph shows the rate of self-discharge of batteries in open circuit conditions [that is either the inverter is switched off or the batteries are not connected with any load and inverter]
From the above graph, you can see that leaving a battery at an ambient of 30℃ for more than 4 months could discharge your batteries by more than 60%. And self-discharging batteries of more than 60% in ideal conditions could permanently damage the battery.
Switching off the inverter by pressing the on/off button located at the front of the inverter will not only switch off the inverter but also the appliances powered by the inverter during power cuts. To make the appliances run even after the inverter is switched off, you need to switch it off as well as bypass the inverter.
To make the appliances running even after the inverter is switched off, you need to switch off as well as bypass the inverter.
Now, there are two types of home inverters available in the market, the first which has bypass contact and the second which doesn’t. Both types of inverters require different procedures to switch off and bypass the inverter.
How to switch off the inverter when not in use
To turn off the inverter first, choose the bypass option using the bypass switch located on the back of the inverter. Then, on the front side of the inverter, you will find the on/off button, press and hold that button until the inverter is switched off.
If your inverter doesn’t have a bypass switch then you need to follow the following steps.
First: Switch off the inverter from the front side button, press and hold it until the inverter is switched off.
Second: Switch off the power socket, power the inverter from the grid, and then unplug the input power plug of the inverter from your home power socket.
Third: Now unplug the output plug of your home inverter, and plug it into the home power socket and switch on it.
In this way, you can switch off as well as bypass your home inverter having no bypass switch.
Frequently Ask Questions
Should the inverter be on all the time?
Yes, you should keep your inverter ON all the time. Otherwise, you will lose your battery backup time due to the self-discharge of batteries. You will need to start the inverter manually every time when grid power failed. Also, the power consumption of batteries during float charging is less than 1% of battery capacity.
What happens if the input of the inverter is switched off for a month?
Switching off your inverter for a month, won’t hurt your inverter but this will discharge your batteries by 4-6%. This is due to the phenomenon called self-discharge of the battery. A Lead-acid battery discharges itself by 4-6% per month when not in use.
Hence if you switch off the input of your inverter for 2 months, your batteries will be discharged by 8 to 12%.
The self-discharge rate of the battery depends upon the ambient temperature of the battery room, age of the battery and percentage of battery charge.
The self-discharge rate is related to ambient temperature. The self-discharge degree is smaller when the ambient temperature is lower, otherwise is larger. The requirement temperature of the battery storage environment is from 0℃ to 35℃. The storage place must be clean, ventilated and dry.
So if you are leaving your home for months, then make sure that your batteries are fully charged and their water level is full. Also, when you come back don’t forget to switch on your inverter.
Do inverters drain batteries?
No, inverters didn’t drain batteries. However, batteries lose energy if the inverter input power is disconnected or they are isolated from the inverter. Hence, batteries are needed to connect with the inverter and the inverter input power is needed to connect with the gird. To keep batteries fully charged.
Do inverters use power when not in use?
Yes, the inverter uses a low current power when not is used, to keep the batteries fully charged. This low current charging of batteries is called float charging or trickle charging of batteries. The amount of low current power required for tickle charging of batteries depends upon the type of battery.
For instance, a flooded battery required more tickle charging current as compared to a sealed battery. Don’t know the difference between flooded and sealed batteries? Click here, to learn more.
Does inverter usage raise power bills?
The inverter uses some sort of power itself and some sort of power for trickle-charging of the batteries to keep them fully charged. Hence use of an inverter increases the power bills. However, this rise in power bills is very negligible and won't make any noticeable change in your power bills.
Furthermore, the total internal power consumption of the inverter is varied from 4 to 8 % of the battery rating per month. For example, if you have a 12V, 150Ah battery your inverter will consume 0.072 to 0.144 units per month.
Hence, the higher rating of your battery will increase the internal power consumption of your inverter.