There seem to be any number of inverters that connect to battery power automatically when the mains goes down.
I am looking for the opposite performing inverter. When the output of the inverter is overloaded I want the inverter to connect to mains power. This means that the inverter would need a mains input as well as a battery input.
I will give an example for clarity. Suppose the inverter can support a load of 200 watts. My refrigerator is 120 watts. So the battery is running my frig.
Then I turn on my electric kettle using 2000 watts. Most inverters would then have a safety cut out for the overload. I want an inverter that would have an inbuilt switch to auto connect to the mains at this point so I can use my kettle. Then when the kettle has boiled I want the inverter to go back to the battery input.
Is there an inverter that can do this? It obviously would need a mains input as well as the battery input.

 

Why are you running on batteries when you have a mains supply???

The idea of an inverter is in the absense of mains, then when the mains is restored it switches off.

 

Why are you running on batteries when you have a mains supply???

The idea of an inverter is in the absense of mains, then when the mains is restored it switches off.

Many UPS systems always run on batteries even when mains power is available. That way, battery charge is maintained easier than detecting when the battery level is low and switching in a charger.

Here, we have a situation where in certain circumstances the battery cannot supply the necessary current. Since this higher current is not always available, it’s a good strategy to switch to mains power. Yes, the batteries/UPS can’t support the high current device, but it’s less expensive and apparently not necessary.